1 /* 2 * Copyright (c) 2012-2017 The DragonFly Project. All rights reserved. 3 * Copyright (c) 1999 Peter Wemm <peter@FreeBSD.org>. All rights reserved. 4 * 5 * This code is derived from software contributed to The DragonFly Project 6 * by Matthew Dillon <dillon@backplane.com>, 7 * by Mihai Carabas <mihai.carabas@gmail.com> 8 * and many others. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in 18 * the documentation and/or other materials provided with the 19 * distribution. 20 * 3. Neither the name of The DragonFly Project nor the names of its 21 * contributors may be used to endorse or promote products derived 22 * from this software without specific, prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 25 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 26 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 27 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 28 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 29 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 30 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 31 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 32 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 33 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 34 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 */ 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/kernel.h> 40 #include <sys/lock.h> 41 #include <sys/queue.h> 42 #include <sys/proc.h> 43 #include <sys/rtprio.h> 44 #include <sys/uio.h> 45 #include <sys/sysctl.h> 46 #include <sys/resourcevar.h> 47 #include <sys/spinlock.h> 48 #include <sys/cpu_topology.h> 49 #include <sys/thread2.h> 50 #include <sys/spinlock2.h> 51 52 #include <sys/ktr.h> 53 54 #include <machine/cpu.h> 55 #include <machine/smp.h> 56 57 /* 58 * Priorities. Note that with 32 run queues per scheduler each queue 59 * represents four priority levels. 60 */ 61 62 int dfly_rebalanced; 63 64 #define MAXPRI 128 65 #define PRIMASK (MAXPRI - 1) 66 #define PRIBASE_REALTIME 0 67 #define PRIBASE_NORMAL MAXPRI 68 #define PRIBASE_IDLE (MAXPRI * 2) 69 #define PRIBASE_THREAD (MAXPRI * 3) 70 #define PRIBASE_NULL (MAXPRI * 4) 71 72 #define NQS 32 /* 32 run queues. */ 73 #define PPQ (MAXPRI / NQS) /* priorities per queue */ 74 #define PPQMASK (PPQ - 1) 75 76 /* 77 * NICE_QS - maximum queues nice can shift the process 78 * EST_QS - maximum queues estcpu can shift the process 79 * 80 * ESTCPUPPQ - number of estcpu units per priority queue 81 * ESTCPUMAX - number of estcpu units 82 * 83 * Remember that NICE runs over the whole -20 to +20 range. 84 */ 85 #define NICE_QS 24 /* -20 to +20 shift in whole queues */ 86 #define EST_QS 20 /* 0-MAX shift in whole queues */ 87 #define ESTCPUPPQ 512 88 #define ESTCPUMAX (ESTCPUPPQ * EST_QS) 89 #define PRIO_RANGE (PRIO_MAX - PRIO_MIN + 1) 90 91 #define ESTCPULIM(v) min((v), ESTCPUMAX) 92 93 TAILQ_HEAD(rq, lwp); 94 95 #define lwp_priority lwp_usdata.dfly.priority 96 #define lwp_forked lwp_usdata.dfly.forked 97 #define lwp_rqindex lwp_usdata.dfly.rqindex 98 #define lwp_estcpu lwp_usdata.dfly.estcpu 99 #define lwp_estfast lwp_usdata.dfly.estfast 100 #define lwp_uload lwp_usdata.dfly.uload 101 #define lwp_rqtype lwp_usdata.dfly.rqtype 102 #define lwp_qcpu lwp_usdata.dfly.qcpu 103 #define lwp_rrcount lwp_usdata.dfly.rrcount 104 105 static __inline int 106 lptouload(struct lwp *lp) 107 { 108 int uload; 109 110 uload = lp->lwp_estcpu / NQS; 111 uload -= uload * lp->lwp_proc->p_nice / (PRIO_MAX + 1); 112 113 return uload; 114 } 115 116 /* 117 * DFly scheduler pcpu structure. Note that the pcpu uload field must 118 * be 64-bits to avoid overflowing in the situation where more than 32768 119 * processes are on a single cpu's queue. Since high-end systems can 120 * easily run 900,000+ processes, we have to deal with it. 121 */ 122 struct usched_dfly_pcpu { 123 struct spinlock spin; 124 struct thread *helper_thread; 125 struct globaldata *gd; 126 u_short scancpu; 127 short upri; 128 long uload; /* 64-bits to avoid overflow (1) */ 129 int ucount; 130 int flags; 131 struct lwp *uschedcp; 132 struct rq queues[NQS]; 133 struct rq rtqueues[NQS]; 134 struct rq idqueues[NQS]; 135 u_int32_t queuebits; 136 u_int32_t rtqueuebits; 137 u_int32_t idqueuebits; 138 int runqcount; 139 int cpuid; 140 cpumask_t cpumask; 141 cpu_node_t *cpunode; 142 } __cachealign; 143 144 /* 145 * Reflecting bits in the global atomic masks allows us to avoid 146 * a certain degree of global ping-ponging. 147 */ 148 #define DFLY_PCPU_RDYMASK 0x0001 /* reflect rdyprocmask */ 149 #define DFLY_PCPU_CURMASK 0x0002 /* reflect curprocmask */ 150 151 typedef struct usched_dfly_pcpu *dfly_pcpu_t; 152 153 static void dfly_acquire_curproc(struct lwp *lp); 154 static void dfly_release_curproc(struct lwp *lp); 155 static void dfly_select_curproc(globaldata_t gd); 156 static void dfly_setrunqueue(struct lwp *lp); 157 static void dfly_setrunqueue_dd(dfly_pcpu_t rdd, struct lwp *lp); 158 static void dfly_schedulerclock(struct lwp *lp, sysclock_t period, 159 sysclock_t cpstamp); 160 static void dfly_recalculate_estcpu(struct lwp *lp); 161 static void dfly_resetpriority(struct lwp *lp); 162 static void dfly_forking(struct lwp *plp, struct lwp *lp); 163 static void dfly_exiting(struct lwp *lp, struct proc *); 164 static void dfly_uload_update(struct lwp *lp); 165 static void dfly_yield(struct lwp *lp); 166 static void dfly_changeqcpu_locked(struct lwp *lp, 167 dfly_pcpu_t dd, dfly_pcpu_t rdd); 168 static dfly_pcpu_t dfly_choose_best_queue(struct lwp *lp); 169 static dfly_pcpu_t dfly_choose_worst_queue(dfly_pcpu_t dd, int forceit); 170 static dfly_pcpu_t dfly_choose_queue_simple(dfly_pcpu_t dd, struct lwp *lp); 171 static void dfly_need_user_resched_remote(void *dummy); 172 static struct lwp *dfly_chooseproc_locked(dfly_pcpu_t rdd, dfly_pcpu_t dd, 173 struct lwp *chklp, int worst); 174 static void dfly_remrunqueue_locked(dfly_pcpu_t dd, struct lwp *lp); 175 static void dfly_setrunqueue_locked(dfly_pcpu_t dd, struct lwp *lp); 176 static void dfly_changedcpu(struct lwp *lp); 177 178 struct usched usched_dfly = { 179 { NULL }, 180 "dfly", "Original DragonFly Scheduler", 181 NULL, /* default registration */ 182 NULL, /* default deregistration */ 183 dfly_acquire_curproc, 184 dfly_release_curproc, 185 dfly_setrunqueue, 186 dfly_schedulerclock, 187 dfly_recalculate_estcpu, 188 dfly_resetpriority, 189 dfly_forking, 190 dfly_exiting, 191 dfly_uload_update, 192 NULL, /* setcpumask not supported */ 193 dfly_yield, 194 dfly_changedcpu 195 }; 196 197 /* 198 * We have NQS (32) run queues per scheduling class. For the normal 199 * class, there are 128 priorities scaled onto these 32 queues. New 200 * processes are added to the last entry in each queue, and processes 201 * are selected for running by taking them from the head and maintaining 202 * a simple FIFO arrangement. Realtime and Idle priority processes have 203 * and explicit 0-31 priority which maps directly onto their class queue 204 * index. When a queue has something in it, the corresponding bit is 205 * set in the queuebits variable, allowing a single read to determine 206 * the state of all 32 queues and then a ffs() to find the first busy 207 * queue. 208 * 209 * curprocmask is used to publish cpus with assigned curprocs to the rest 210 * of the cpus. In certain situations curprocmask may leave a bit set 211 * (e.g. a yield or a token-based yield) even though dd->uschedcp is 212 * NULL'd out temporarily). 213 */ 214 /* currently running a user process */ 215 static cpumask_t dfly_curprocmask = CPUMASK_INITIALIZER_ALLONES; 216 static cpumask_t dfly_rdyprocmask; /* ready to accept a user process */ 217 static struct usched_dfly_pcpu dfly_pcpu[MAXCPU]; 218 static struct sysctl_ctx_list usched_dfly_sysctl_ctx; 219 static struct sysctl_oid *usched_dfly_sysctl_tree; 220 static struct lock usched_dfly_config_lk = LOCK_INITIALIZER("usdfs", 0, 0); 221 222 /* Debug info exposed through debug.* sysctl */ 223 224 static int usched_dfly_debug = -1; 225 SYSCTL_INT(_debug, OID_AUTO, dfly_scdebug, CTLFLAG_RW, 226 &usched_dfly_debug, 0, 227 "Print debug information for this pid"); 228 229 static int usched_dfly_pid_debug = -1; 230 SYSCTL_INT(_debug, OID_AUTO, dfly_pid_debug, CTLFLAG_RW, 231 &usched_dfly_pid_debug, 0, 232 "Print KTR debug information for this pid"); 233 234 static int usched_dfly_chooser = 0; 235 SYSCTL_INT(_debug, OID_AUTO, dfly_chooser, CTLFLAG_RW, 236 &usched_dfly_chooser, 0, 237 "Print KTR debug information for this pid"); 238 239 /* 240 * WARNING! 241 * 242 * The fork bias can have a large effect on the system in the face of a 243 * make -j N or other high-forking applications. 244 * 245 * Larger values are much less invasive vs other things that 246 * might be running in the system, but can cause exec chains 247 * such as those typically generated by make to have higher 248 * latencies in the face of modest load. 249 * 250 * Lower values are more invasive but have reduced latencies 251 * for such exec chains. 252 * 253 * make -j 10 buildkernel example, build times: 254 * 255 * +0 3:04 256 * +1 3:14 -5.2% <-- default 257 * +2 3:22 -8.9% 258 * 259 * This issue occurs due to the way the scheduler affinity heuristics work. 260 * There is no way to really 'fix' the affinity heuristics because when it 261 * comes right down to it trying to instantly schedule a process on an 262 * available cpu (even if it will become unavailable a microsecond later) 263 * tends to cause processes to shift around between cpus and sockets too much 264 * and breaks the affinity. 265 * 266 * NOTE: Heavily concurrent builds typically have enough things on the pan 267 * that they remain time-efficient even with a higher bias. 268 */ 269 static int usched_dfly_forkbias = 1; 270 SYSCTL_INT(_debug, OID_AUTO, dfly_forkbias, CTLFLAG_RW, 271 &usched_dfly_forkbias, 0, 272 "Fork bias for estcpu in whole queues"); 273 274 /* 275 * Tunning usched_dfly - configurable through kern.usched_dfly. 276 * 277 * weight1 - Tries to keep threads on their current cpu. If you 278 * make this value too large the scheduler will not be 279 * able to load-balance large loads. 280 * 281 * Generally set to a fairly low value, but high enough 282 * such that estcpu jitter doesn't move threads around. 283 * 284 * weight2 - If non-zero, detects thread pairs undergoing synchronous 285 * communications and tries to move them closer together. 286 * The weight advantages the same package and socket and 287 * disadvantages the same core and same cpu. 288 * 289 * WARNING! Weight2 is a ridiculously sensitive parameter, 290 * particularly against weight4. change the default at your 291 * peril. 292 * 293 * weight3 - Weighting based on the number of recently runnable threads 294 * on the userland scheduling queue (ignoring their loads). 295 * 296 * A nominal value here prevents high-priority (low-load) 297 * threads from accumulating on one cpu core when other 298 * cores are available. 299 * 300 * This value should be left fairly small because low-load 301 * high priority threads can still be mostly idle and too 302 * high a value will kick cpu-bound processes off the cpu 303 * unnecessarily. 304 * 305 * weight4 - Weighting based on availability of other logical cpus running 306 * less important threads (by upri) than the thread we are trying 307 * to schedule. 308 * 309 * This allows a thread to migrate to another nearby cpu if it 310 * is unable to run on the current cpu based on the other cpu 311 * being idle or running a less important (higher lwp_priority) 312 * thread. This value should be large enough to override weight1, 313 * but not so large as to override weight2. 314 * 315 * This parameter generally ensures fairness at the cost of some 316 * performance (if set to too high). It should generally be just 317 * a tad lower than weight2. 318 * 319 * weight5 - Weighting based on the relative amount of ram connected 320 * to the node a cpu resides on. 321 * 322 * This value should remain fairly low to allow assymetric 323 * NUMA nodes to get threads scheduled to them. Setting a very 324 * high level will prevent scheduling on assymetric NUMA nodes 325 * with low amounts of directly-attached memory. 326 * 327 * Note that when testing e.g. N threads on a machine with N 328 * cpu cores with assymtric NUMA nodes, a non-zero value will 329 * cause some cpu threads on the low-priority NUMA nodes to remain 330 * idle even when a few process threads are doubled-up on other 331 * cpus. But this is typically more ideal because it deschedules 332 * low-priority NUMA nodes at lighter nodes. 333 * 334 * Values between 50 and 200 are recommended. Default is 50. 335 * 336 * weight6 - rdd transfer weight hysteresis. Defaults to 0, can be increased 337 * to improve stabillity at the cost of more mis-schedules. 338 * 339 * ipc_smt - If enabled, advantage IPC pairing to sibling cpu threads. 340 * If -1, automatic when load >= 1/2 ncpus (default). 341 * 342 * ipc_same- If enabled, advantage IPC pairing to the same logical cpu. 343 * If -1, automatic when load >= ncpus (default). 344 * 345 * features - These flags can be set or cleared to enable or disable various 346 * features. 347 * 348 * 0x01 Enable idle-cpu pulling (default) 349 * 0x02 Enable proactive pushing (default) 350 * 0x04 Enable rebalancing rover (default) 351 * 0x08 Enable more proactive pushing (default) 352 * 0x10 (unassigned) 353 * 0x20 choose best cpu for forked process (default) 354 * 0x40 choose current cpu for forked process 355 * 0x80 choose random cpu for forked process 356 * 357 * NOTE - The idea behind forking mechanic 0x20 is that most 358 * fork()ing is either followed by an exec in the child, 359 * or the parent wait*()s. If the child is short-lived, 360 * there is effectively an IPC dependency (td_wakefromcpu 361 * is also set in kern_fork.c) and we want to implement 362 * the weight2 behavior to reduce IPIs and to reduce CPU 363 * cache ping-ponging. 364 */ 365 __read_mostly static int usched_dfly_smt = 0; 366 __read_mostly static int usched_dfly_cache_coherent = 0; 367 __read_mostly static int usched_dfly_weight1 = 30; /* keep thread on cpu */ 368 __read_mostly static int usched_dfly_weight2 = 180; /* IPC locality */ 369 __read_mostly static int usched_dfly_weight3 = 10; /* threads on queue */ 370 __read_mostly static int usched_dfly_weight4 = 120; /* availability of cores */ 371 __read_mostly static int usched_dfly_weight5 = 50; /* node attached memory */ 372 __read_mostly static int usched_dfly_weight6 = 0; /* rdd transfer weight */ 373 __read_mostly static int usched_dfly_features = 0x2f; /* allow pulls */ 374 __read_mostly static int usched_dfly_fast_resched = PPQ / 2; /* delta pri */ 375 __read_mostly static int usched_dfly_swmask = ~PPQMASK; /* allow pulls */ 376 __read_mostly static int usched_dfly_rrinterval = (ESTCPUFREQ + 9) / 10; 377 __read_mostly static int usched_dfly_decay = 8; 378 __read_mostly static int usched_dfly_ipc_smt = -1; /* IPC auto smt pair */ 379 __read_mostly static int usched_dfly_ipc_same = -1; /* IPC auto same log cpu */ 380 __read_mostly static long usched_dfly_node_mem; 381 382 /* KTR debug printings */ 383 384 KTR_INFO_MASTER(usched); 385 386 #if !defined(KTR_USCHED_DFLY) 387 #define KTR_USCHED_DFLY KTR_ALL 388 #endif 389 390 KTR_INFO(KTR_USCHED_DFLY, usched, chooseproc, 0, 391 "USCHED_DFLY(chooseproc: pid %d, old_cpuid %d, curr_cpuid %d)", 392 pid_t pid, int old_cpuid, int curr); 393 394 /* 395 * This function is called when the kernel intends to return to userland. 396 * It is responsible for making the thread the current designated userland 397 * thread for this cpu, blocking if necessary. 398 * 399 * The kernel will not depress our LWKT priority until after we return, 400 * in case we have to shove over to another cpu. 401 * 402 * We must determine our thread's disposition before we switch away. This 403 * is very sensitive code. 404 * 405 * WARNING! THIS FUNCTION IS ALLOWED TO CAUSE THE CURRENT THREAD TO MIGRATE 406 * TO ANOTHER CPU! Because most of the kernel assumes that no migration will 407 * occur, this function is called only under very controlled circumstances. 408 */ 409 static void 410 dfly_acquire_curproc(struct lwp *lp) 411 { 412 globaldata_t gd; 413 dfly_pcpu_t dd; 414 dfly_pcpu_t rdd; 415 thread_t td; 416 int force_resched; 417 418 /* 419 * Make sure we aren't sitting on a tsleep queue. 420 */ 421 td = lp->lwp_thread; 422 crit_enter_quick(td); 423 if (td->td_flags & TDF_TSLEEPQ) 424 tsleep_remove(td); 425 dfly_recalculate_estcpu(lp); 426 427 gd = mycpu; 428 dd = &dfly_pcpu[gd->gd_cpuid]; 429 430 /* 431 * Process any pending interrupts/ipi's, then handle reschedule 432 * requests. dfly_release_curproc() will try to assign a new 433 * uschedcp that isn't us and otherwise NULL it out. 434 */ 435 force_resched = 0; 436 if ((td->td_mpflags & TDF_MP_BATCH_DEMARC) && 437 lp->lwp_rrcount >= usched_dfly_rrinterval / 2) { 438 force_resched = 1; 439 } 440 441 if (user_resched_wanted()) { 442 if (dd->uschedcp == lp) 443 force_resched = 1; 444 clear_user_resched(); 445 dfly_release_curproc(lp); 446 } 447 448 /* 449 * Loop until we are the current user thread. 450 * 451 * NOTE: dd spinlock not held at top of loop. 452 */ 453 if (dd->uschedcp == lp) 454 lwkt_yield_quick(); 455 456 while (dd->uschedcp != lp) { 457 /* 458 * Do not do a lwkt_yield_quick() here as it will prevent 459 * the lwp from being placed on the dfly_bsd runqueue for 460 * one cycle (possibly an entire round-robin), preventing 461 * it from being scheduled to another cpu. 462 */ 463 /* lwkt_yield_quick(); */ 464 465 if (usched_dfly_debug == lp->lwp_proc->p_pid) 466 kprintf(" pid %d acquire curcpu %d (force %d) ", 467 lp->lwp_proc->p_pid, gd->gd_cpuid, 468 force_resched); 469 470 471 spin_lock(&dd->spin); 472 473 /* This lwp is an outcast; force reschedule. */ 474 if (__predict_false( 475 CPUMASK_TESTBIT(lp->lwp_cpumask, gd->gd_cpuid) == 0) && 476 (rdd = dfly_choose_best_queue(lp)) != dd) { 477 dfly_changeqcpu_locked(lp, dd, rdd); 478 spin_unlock(&dd->spin); 479 lwkt_deschedule(lp->lwp_thread); 480 dfly_setrunqueue_dd(rdd, lp); 481 lwkt_switch(); 482 gd = mycpu; 483 dd = &dfly_pcpu[gd->gd_cpuid]; 484 if (usched_dfly_debug == lp->lwp_proc->p_pid) 485 kprintf("SEL-A cpu %d\n", gd->gd_cpuid); 486 continue; 487 } 488 489 /* 490 * We are not or are no longer the current lwp and a forced 491 * reschedule was requested. Figure out the best cpu to 492 * run on (our current cpu will be given significant weight). 493 * 494 * Doing this on many cpus simultaneously leads to 495 * instability so pace the operation. 496 * 497 * (if a reschedule was not requested we want to move this 498 * step after the uschedcp tests). 499 */ 500 if (force_resched && 501 (usched_dfly_features & 0x08) && 502 (u_int)sched_ticks / 8 % ncpus == gd->gd_cpuid) { 503 if ((rdd = dfly_choose_best_queue(lp)) != dd) { 504 dfly_changeqcpu_locked(lp, dd, rdd); 505 spin_unlock(&dd->spin); 506 lwkt_deschedule(lp->lwp_thread); 507 dfly_setrunqueue_dd(rdd, lp); 508 lwkt_switch(); 509 gd = mycpu; 510 dd = &dfly_pcpu[gd->gd_cpuid]; 511 if (usched_dfly_debug == lp->lwp_proc->p_pid) 512 kprintf("SEL-B cpu %d\n", gd->gd_cpuid); 513 continue; 514 } 515 if (usched_dfly_debug == lp->lwp_proc->p_pid) 516 kprintf("(SEL-B same cpu) "); 517 } 518 519 /* 520 * Either no reschedule was requested or the best queue was 521 * dd, and no current process has been selected. We can 522 * trivially become the current lwp on the current cpu. 523 */ 524 if (dd->uschedcp == NULL) { 525 atomic_clear_int(&lp->lwp_thread->td_mpflags, 526 TDF_MP_DIDYIELD); 527 if ((dd->flags & DFLY_PCPU_CURMASK) == 0) { 528 ATOMIC_CPUMASK_ORBIT(dfly_curprocmask, 529 gd->gd_cpuid); 530 dd->flags |= DFLY_PCPU_CURMASK; 531 } 532 dd->uschedcp = lp; 533 dd->upri = lp->lwp_priority; 534 KKASSERT(lp->lwp_qcpu == dd->cpuid); 535 spin_unlock(&dd->spin); 536 if (usched_dfly_debug == lp->lwp_proc->p_pid) 537 kprintf("SEL-C cpu %d (same cpu)\n", 538 gd->gd_cpuid); 539 break; 540 } 541 542 /* 543 * Can we steal the current designated user thread? 544 * 545 * If we do the other thread will stall when it tries to 546 * return to userland, possibly rescheduling elsewhere. 547 * Set need_user_resched() to get the thread to cycle soonest. 548 * 549 * It is important to do a masked test to avoid the edge 550 * case where two near-equal-priority threads are constantly 551 * interrupting each other. 552 * 553 * In the exact match case another thread has already gained 554 * uschedcp and lowered its priority, if we steal it the 555 * other thread will stay stuck on the LWKT runq and not 556 * push to another cpu. So don't steal on equal-priority even 557 * though it might appear to be more beneficial due to not 558 * having to switch back to the other thread's context. 559 * 560 * usched_dfly_fast_resched requires that two threads be 561 * significantly far apart in priority in order to interrupt. 562 * 563 * If better but not sufficiently far apart, the current 564 * uschedcp will be interrupted at the next scheduler clock. 565 */ 566 if (dd->uschedcp && 567 (dd->upri & ~PPQMASK) > 568 (lp->lwp_priority & ~PPQMASK) + usched_dfly_fast_resched) { 569 dd->uschedcp = lp; 570 dd->upri = lp->lwp_priority; 571 KKASSERT(lp->lwp_qcpu == dd->cpuid); 572 need_user_resched(); 573 spin_unlock(&dd->spin); 574 if (usched_dfly_debug == lp->lwp_proc->p_pid) 575 kprintf("SEL-D cpu %d (same cpu)\n", 576 gd->gd_cpuid); 577 break; 578 } 579 580 /* 581 * Requeue us at lwp_priority, which recalculate_estcpu() 582 * set for us. Reset the rrcount to force placement 583 * at the end of the queue. 584 * 585 * We used to move ourselves to the worst queue, but 586 * this creates a fairly serious priority inversion 587 * problem. 588 */ 589 if (lp->lwp_thread->td_mpflags & TDF_MP_DIDYIELD) { 590 spin_unlock(&dd->spin); 591 lp->lwp_rrcount = usched_dfly_rrinterval; 592 lp->lwp_rqindex = (lp->lwp_priority & PRIMASK) / PPQ; 593 594 lwkt_deschedule(lp->lwp_thread); 595 dfly_setrunqueue_dd(dd, lp); 596 atomic_clear_int(&lp->lwp_thread->td_mpflags, 597 TDF_MP_DIDYIELD); 598 lwkt_switch(); 599 gd = mycpu; 600 dd = &dfly_pcpu[gd->gd_cpuid]; 601 if (usched_dfly_debug == lp->lwp_proc->p_pid) 602 kprintf("SEL-E cpu %d (requeue)\n", 603 gd->gd_cpuid); 604 continue; 605 } 606 607 /* 608 * We are not the current lwp, figure out the best cpu 609 * to run on (our current cpu will be given significant 610 * weight). Loop on cpu change. 611 */ 612 if ((usched_dfly_features & 0x02) && 613 force_resched == 0 && 614 (rdd = dfly_choose_best_queue(lp)) != dd) { 615 dfly_changeqcpu_locked(lp, dd, rdd); 616 spin_unlock(&dd->spin); 617 lwkt_deschedule(lp->lwp_thread); 618 dfly_setrunqueue_dd(rdd, lp); 619 lwkt_switch(); 620 gd = mycpu; 621 dd = &dfly_pcpu[gd->gd_cpuid]; 622 if (usched_dfly_debug == lp->lwp_proc->p_pid) 623 kprintf("SEL-F cpu %d (requeue new cpu)\n", 624 gd->gd_cpuid); 625 continue; 626 } 627 628 /* 629 * We cannot become the current lwp, place the lp on the 630 * run-queue of this or another cpu and deschedule ourselves. 631 * 632 * When we are reactivated we will have another chance. 633 * 634 * Reload after a switch or setrunqueue/switch possibly 635 * moved us to another cpu. 636 */ 637 spin_unlock(&dd->spin); 638 lwkt_deschedule(lp->lwp_thread); 639 dfly_setrunqueue_dd(dd, lp); 640 lwkt_switch(); 641 gd = mycpu; 642 dd = &dfly_pcpu[gd->gd_cpuid]; 643 if (usched_dfly_debug == lp->lwp_proc->p_pid) 644 kprintf("SEL-G cpu %d (fallback setrunq)\n", 645 gd->gd_cpuid); 646 } 647 if (usched_dfly_debug == lp->lwp_proc->p_pid) 648 kprintf(" pid %d acquire DONE cpu %d\n", 649 lp->lwp_proc->p_pid, gd->gd_cpuid); 650 651 /* 652 * Make sure upri is synchronized, then yield to LWKT threads as 653 * needed before returning. This could result in another reschedule. 654 * XXX 655 */ 656 crit_exit_quick(td); 657 658 KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); 659 } 660 661 /* 662 * DFLY_RELEASE_CURPROC 663 * 664 * This routine detaches the current thread from the userland scheduler, 665 * usually because the thread needs to run or block in the kernel (at 666 * kernel priority) for a while. 667 * 668 * This routine is also responsible for selecting a new thread to 669 * make the current thread. 670 * 671 * NOTE: This implementation differs from the dummy example in that 672 * dfly_select_curproc() is able to select the current process, whereas 673 * dummy_select_curproc() is not able to select the current process. 674 * This means we have to NULL out uschedcp. 675 * 676 * Additionally, note that we may already be on a run queue if releasing 677 * via the lwkt_switch() in dfly_setrunqueue(). 678 */ 679 static void 680 dfly_release_curproc(struct lwp *lp) 681 { 682 globaldata_t gd = mycpu; 683 dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid]; 684 685 /* 686 * Make sure td_wakefromcpu is defaulted. This will be overwritten 687 * by wakeup(). 688 */ 689 if (dd->uschedcp == lp) { 690 KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); 691 spin_lock(&dd->spin); 692 if (dd->uschedcp == lp) { 693 dd->uschedcp = NULL; /* don't let lp be selected */ 694 dd->upri = PRIBASE_NULL; 695 696 /* 697 * We're just going to set it again, avoid the global 698 * cache line ping-pong. 699 */ 700 if ((lp->lwp_thread->td_mpflags & TDF_MP_DIDYIELD) == 0) { 701 if (dd->flags & DFLY_PCPU_CURMASK) { 702 ATOMIC_CPUMASK_NANDBIT(dfly_curprocmask, 703 gd->gd_cpuid); 704 dd->flags &= ~DFLY_PCPU_CURMASK; 705 } 706 } 707 spin_unlock(&dd->spin); 708 dfly_select_curproc(gd); 709 } else { 710 spin_unlock(&dd->spin); 711 } 712 } 713 } 714 715 /* 716 * DFLY_SELECT_CURPROC 717 * 718 * Select a new current process for this cpu and clear any pending user 719 * reschedule request. The cpu currently has no current process. 720 * 721 * This routine is also responsible for equal-priority round-robining, 722 * typically triggered from dfly_schedulerclock(). In our dummy example 723 * all the 'user' threads are LWKT scheduled all at once and we just 724 * call lwkt_switch(). 725 * 726 * The calling process is not on the queue and cannot be selected. 727 */ 728 static 729 void 730 dfly_select_curproc(globaldata_t gd) 731 { 732 dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid]; 733 struct lwp *nlp; 734 int cpuid = gd->gd_cpuid; 735 736 crit_enter_gd(gd); 737 738 spin_lock(&dd->spin); 739 nlp = dfly_chooseproc_locked(dd, dd, dd->uschedcp, 0); 740 741 if (nlp) { 742 if ((dd->flags & DFLY_PCPU_CURMASK) == 0) { 743 ATOMIC_CPUMASK_ORBIT(dfly_curprocmask, cpuid); 744 dd->flags |= DFLY_PCPU_CURMASK; 745 } 746 dd->upri = nlp->lwp_priority; 747 dd->uschedcp = nlp; 748 #if 0 749 dd->rrcount = 0; /* reset round robin */ 750 #endif 751 spin_unlock(&dd->spin); 752 lwkt_acquire(nlp->lwp_thread); 753 lwkt_schedule(nlp->lwp_thread); 754 } else { 755 spin_unlock(&dd->spin); 756 } 757 crit_exit_gd(gd); 758 } 759 760 /* 761 * Place the specified lwp on the user scheduler's run queue. This routine 762 * must be called with the thread descheduled. The lwp must be runnable. 763 * It must not be possible for anyone else to explicitly schedule this thread. 764 * 765 * The thread may be the current thread as a special case. 766 */ 767 static void 768 dfly_setrunqueue(struct lwp *lp) 769 { 770 dfly_pcpu_t dd; 771 dfly_pcpu_t rdd; 772 773 /* 774 * First validate the process LWKT state. 775 */ 776 KASSERT(lp->lwp_stat == LSRUN, ("setrunqueue: lwp not LSRUN")); 777 KASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0, 778 ("lwp %d/%d already on runq! flag %08x/%08x", lp->lwp_proc->p_pid, 779 lp->lwp_tid, lp->lwp_proc->p_flags, lp->lwp_flags)); 780 KKASSERT((lp->lwp_thread->td_flags & TDF_RUNQ) == 0); 781 782 /* 783 * NOTE: dd/rdd do not necessarily represent the current cpu. 784 * Instead they may represent the cpu the thread was last 785 * scheduled on or inherited by its parent. 786 */ 787 dd = &dfly_pcpu[lp->lwp_qcpu]; 788 rdd = dd; 789 790 /* 791 * This process is not supposed to be scheduled anywhere or assigned 792 * as the current process anywhere. Assert the condition. 793 */ 794 KKASSERT(rdd->uschedcp != lp); 795 796 /* 797 * Ok, we have to setrunqueue some target cpu and request a reschedule 798 * if necessary. 799 * 800 * We have to choose the best target cpu. It might not be the current 801 * target even if the current cpu has no running user thread (for 802 * example, because the current cpu might be a hyperthread and its 803 * sibling has a thread assigned). 804 * 805 * If we just forked it is most optimal to run the child on the same 806 * cpu just in case the parent decides to wait for it (thus getting 807 * off that cpu). As long as there is nothing else runnable on the 808 * cpu, that is. If we did this unconditionally a parent forking 809 * multiple children before waiting (e.g. make -j N) leaves other 810 * cpus idle that could be working. 811 */ 812 if (lp->lwp_forked) { 813 lp->lwp_forked = 0; 814 if (usched_dfly_features & 0x20) 815 rdd = dfly_choose_best_queue(lp); 816 else if (usched_dfly_features & 0x40) 817 rdd = &dfly_pcpu[lp->lwp_qcpu]; 818 else if (usched_dfly_features & 0x80) 819 rdd = dfly_choose_queue_simple(rdd, lp); 820 else if (dfly_pcpu[lp->lwp_qcpu].runqcount) 821 rdd = dfly_choose_best_queue(lp); 822 else 823 rdd = &dfly_pcpu[lp->lwp_qcpu]; 824 } else { 825 rdd = dfly_choose_best_queue(lp); 826 /* rdd = &dfly_pcpu[lp->lwp_qcpu]; */ 827 } 828 if (lp->lwp_qcpu != rdd->cpuid) { 829 spin_lock(&dd->spin); 830 dfly_changeqcpu_locked(lp, dd, rdd); 831 spin_unlock(&dd->spin); 832 } 833 dfly_setrunqueue_dd(rdd, lp); 834 } 835 836 /* 837 * Change qcpu to rdd->cpuid. The dd the lp is CURRENTLY on must be 838 * spin-locked on-call. rdd does not have to be. 839 */ 840 static void 841 dfly_changeqcpu_locked(struct lwp *lp, dfly_pcpu_t dd, dfly_pcpu_t rdd) 842 { 843 if (lp->lwp_qcpu != rdd->cpuid) { 844 if (lp->lwp_mpflags & LWP_MP_ULOAD) { 845 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ULOAD); 846 atomic_add_long(&dd->uload, -lp->lwp_uload); 847 atomic_add_int(&dd->ucount, -1); 848 } 849 lp->lwp_qcpu = rdd->cpuid; 850 } 851 } 852 853 /* 854 * Place lp on rdd's runqueue. Nothing is locked on call. This function 855 * also performs all necessary ancillary notification actions. 856 */ 857 static void 858 dfly_setrunqueue_dd(dfly_pcpu_t rdd, struct lwp *lp) 859 { 860 globaldata_t rgd; 861 862 /* 863 * We might be moving the lp to another cpu's run queue, and once 864 * on the runqueue (even if it is our cpu's), another cpu can rip 865 * it away from us. 866 * 867 * TDF_MIGRATING might already be set if this is part of a 868 * remrunqueue+setrunqueue sequence. 869 */ 870 if ((lp->lwp_thread->td_flags & TDF_MIGRATING) == 0) 871 lwkt_giveaway(lp->lwp_thread); 872 873 rgd = rdd->gd; 874 875 /* 876 * We lose control of the lp the moment we release the spinlock 877 * after having placed it on the queue. i.e. another cpu could pick 878 * it up, or it could exit, or its priority could be further 879 * adjusted, or something like that. 880 * 881 * WARNING! rdd can point to a foreign cpu! 882 */ 883 spin_lock(&rdd->spin); 884 dfly_setrunqueue_locked(rdd, lp); 885 886 /* 887 * Potentially interrupt the currently-running thread 888 */ 889 if ((rdd->upri & ~PPQMASK) <= (lp->lwp_priority & ~PPQMASK)) { 890 /* 891 * Currently running thread is better or same, do not 892 * interrupt. 893 */ 894 spin_unlock(&rdd->spin); 895 } else if ((rdd->upri & ~PPQMASK) <= (lp->lwp_priority & ~PPQMASK) + 896 usched_dfly_fast_resched) { 897 /* 898 * Currently running thread is not better, but not so bad 899 * that we need to interrupt it. Let it run for one more 900 * scheduler tick. 901 */ 902 if (rdd->uschedcp && 903 rdd->uschedcp->lwp_rrcount < usched_dfly_rrinterval) { 904 rdd->uschedcp->lwp_rrcount = usched_dfly_rrinterval - 1; 905 } 906 spin_unlock(&rdd->spin); 907 } else if (rgd == mycpu) { 908 /* 909 * We should interrupt the currently running thread, which 910 * is on the current cpu. However, if DIDYIELD is set we 911 * round-robin unconditionally and do not interrupt it. 912 */ 913 spin_unlock(&rdd->spin); 914 if (rdd->uschedcp == NULL) 915 wakeup_mycpu(rdd->helper_thread); /* XXX */ 916 if ((lp->lwp_thread->td_mpflags & TDF_MP_DIDYIELD) == 0) 917 need_user_resched(); 918 } else { 919 /* 920 * We should interrupt the currently running thread, which 921 * is on a different cpu. 922 */ 923 spin_unlock(&rdd->spin); 924 lwkt_send_ipiq(rgd, dfly_need_user_resched_remote, NULL); 925 } 926 } 927 928 /* 929 * This routine is called from a systimer IPI. It MUST be MP-safe and 930 * the BGL IS NOT HELD ON ENTRY. This routine is called at ESTCPUFREQ on 931 * each cpu. 932 */ 933 static 934 void 935 dfly_schedulerclock(struct lwp *lp, sysclock_t period, sysclock_t cpstamp) 936 { 937 globaldata_t gd = mycpu; 938 dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid]; 939 940 /* 941 * Spinlocks also hold a critical section so there should not be 942 * any active. 943 */ 944 KKASSERT(gd->gd_spinlocks == 0 || dumping); 945 946 /* 947 * If lp is NULL we might be contended and lwkt_switch() may have 948 * cycled into the idle thread. Apply the tick to the current 949 * process on this cpu if it is contended. 950 */ 951 if (gd->gd_curthread == &gd->gd_idlethread) { 952 lp = dd->uschedcp; 953 if (lp && (lp->lwp_thread == NULL || 954 lp->lwp_thread->td_contended == 0)) { 955 lp = NULL; 956 } 957 } 958 959 /* 960 * Dock thread for tick 961 */ 962 if (lp) { 963 /* 964 * Do we need to round-robin? We round-robin 10 times a 965 * second. This should only occur for cpu-bound batch 966 * processes. 967 */ 968 if (++lp->lwp_rrcount >= usched_dfly_rrinterval) 969 need_user_resched(); 970 971 /* 972 * Adjust estcpu upward using a real time equivalent 973 * calculation, and recalculate lp's priority. Estcpu 974 * is increased such that it will cap-out over a period 975 * of one second. 976 */ 977 lp->lwp_estcpu = ESTCPULIM(lp->lwp_estcpu + 978 ESTCPUMAX / ESTCPUFREQ + 1); 979 dfly_resetpriority(lp); 980 } 981 982 /* 983 * Rebalance two cpus every 8 ticks, pulling the worst thread 984 * from the worst cpu's queue into a rotating cpu number. 985 * Also require that the moving of the highest-load thread 986 * from rdd to dd does not cause the uload to cross over. 987 * 988 * This mechanic is needed because the push algorithms can 989 * steady-state in an non-optimal configuration. We need to mix it 990 * up a little, even if it means breaking up a paired thread, so 991 * the push algorithms can rebalance the degenerate conditions. 992 * This portion of the algorithm exists to ensure stability at the 993 * selected weightings. 994 * 995 * Because we might be breaking up optimal conditions we do not want 996 * to execute this too quickly, hence we only rebalance approximately 997 * ~7-8 times per second. The push's, on the otherhand, are capable 998 * moving threads to other cpus at a much higher rate. 999 * 1000 * We choose the most heavily loaded thread from the worst queue 1001 * in order to ensure that multiple heavy-weight threads on the same 1002 * queue get broken up, and also because these threads are the most 1003 * likely to be able to remain in place. Hopefully then any pairings, 1004 * if applicable, migrate to where these threads are. 1005 */ 1006 if ((usched_dfly_features & 0x04) && 1007 ((u_int)sched_ticks & 7) == 0 && 1008 (u_int)sched_ticks / 8 % ncpus == gd->gd_cpuid) { 1009 /* 1010 * Our cpu is up. 1011 */ 1012 struct lwp *nlp; 1013 dfly_pcpu_t rdd; 1014 1015 rdd = dfly_choose_worst_queue(dd, 1); 1016 if (rdd && dd->uload + usched_dfly_weight6 / 2 < rdd->uload) { 1017 spin_lock(&dd->spin); 1018 if (spin_trylock(&rdd->spin)) { 1019 nlp = dfly_chooseproc_locked(rdd, dd, NULL, 1); 1020 spin_unlock(&rdd->spin); 1021 if (nlp == NULL) 1022 spin_unlock(&dd->spin); 1023 } else { 1024 spin_unlock(&dd->spin); 1025 nlp = NULL; 1026 } 1027 } else { 1028 nlp = NULL; 1029 } 1030 /* dd->spin held if nlp != NULL */ 1031 1032 /* 1033 * Either schedule it or add it to our queue. 1034 */ 1035 if (nlp && 1036 (nlp->lwp_priority & ~PPQMASK) < (dd->upri & ~PPQMASK)) { 1037 if ((dd->flags & DFLY_PCPU_CURMASK) == 0) { 1038 ATOMIC_CPUMASK_ORMASK(dfly_curprocmask, 1039 dd->cpumask); 1040 dd->flags |= DFLY_PCPU_CURMASK; 1041 } 1042 dd->upri = nlp->lwp_priority; 1043 dd->uschedcp = nlp; 1044 #if 0 1045 dd->rrcount = 0; /* reset round robin */ 1046 #endif 1047 spin_unlock(&dd->spin); 1048 lwkt_acquire(nlp->lwp_thread); 1049 lwkt_schedule(nlp->lwp_thread); 1050 } else if (nlp) { 1051 dfly_setrunqueue_locked(dd, nlp); 1052 spin_unlock(&dd->spin); 1053 } 1054 } 1055 } 1056 1057 /* 1058 * Called from acquire and from kern_synch's one-second timer (one of the 1059 * callout helper threads) with a critical section held. 1060 * 1061 * Adjust p_estcpu based on our single-cpu load, p_nice, and compensate for 1062 * overall system load. 1063 * 1064 * Note that no recalculation occurs for a process which sleeps and wakes 1065 * up in the same tick. That is, a system doing thousands of context 1066 * switches per second will still only do serious estcpu calculations 1067 * ESTCPUFREQ times per second. 1068 */ 1069 static 1070 void 1071 dfly_recalculate_estcpu(struct lwp *lp) 1072 { 1073 globaldata_t gd = mycpu; 1074 sysclock_t cpbase; 1075 sysclock_t ttlticks; 1076 int estcpu; 1077 int decay_factor; 1078 int ucount; 1079 1080 /* 1081 * We have to subtract periodic to get the last schedclock 1082 * timeout time, otherwise we would get the upcoming timeout. 1083 * Keep in mind that a process can migrate between cpus and 1084 * while the scheduler clock should be very close, boundary 1085 * conditions could lead to a small negative delta. 1086 */ 1087 cpbase = gd->gd_schedclock.time - gd->gd_schedclock.periodic; 1088 1089 if (lp->lwp_slptime > 1) { 1090 /* 1091 * Too much time has passed, do a coarse correction. 1092 */ 1093 lp->lwp_estcpu = lp->lwp_estcpu >> 1; 1094 dfly_resetpriority(lp); 1095 lp->lwp_cpbase = cpbase; 1096 lp->lwp_cpticks = 0; 1097 lp->lwp_estfast = 0; 1098 } else if (lp->lwp_cpbase != cpbase) { 1099 /* 1100 * Adjust estcpu if we are in a different tick. Don't waste 1101 * time if we are in the same tick. 1102 * 1103 * First calculate the number of ticks in the measurement 1104 * interval. The ttlticks calculation can wind up 0 due to 1105 * a bug in the handling of lwp_slptime (as yet not found), 1106 * so make sure we do not get a divide by 0 panic. 1107 */ 1108 ttlticks = (cpbase - lp->lwp_cpbase) / 1109 gd->gd_schedclock.periodic; 1110 if ((ssysclock_t)ttlticks < 0) { 1111 ttlticks = 0; 1112 lp->lwp_cpbase = cpbase; 1113 } 1114 if (ttlticks < 4) 1115 return; 1116 updatepcpu(lp, lp->lwp_cpticks, ttlticks); 1117 1118 /* 1119 * Calculate instant estcpu based percentage of (one) cpu 1120 * used and exponentially average it into the current 1121 * lwp_estcpu. 1122 */ 1123 ucount = dfly_pcpu[lp->lwp_qcpu].ucount; 1124 estcpu = lp->lwp_cpticks * ESTCPUMAX / ttlticks; 1125 1126 /* 1127 * The higher ttlticks gets, the more meaning the calculation 1128 * has and the smaller our decay_factor in the exponential 1129 * average. 1130 * 1131 * The uload calculation has been removed because it actually 1132 * makes things worse, causing processes which use less cpu 1133 * (such as a browser) to be pumped up and treated the same 1134 * as a cpu-bound process (such as a make). The same effect 1135 * can occur with sufficient load without the uload 1136 * calculation, but occurs less quickly and takes more load. 1137 * In addition, the less cpu a process uses the smaller the 1138 * effect of the overload. 1139 */ 1140 if (ttlticks >= hz) 1141 decay_factor = 1; 1142 else 1143 decay_factor = hz - ttlticks; 1144 1145 lp->lwp_estcpu = ESTCPULIM( 1146 (lp->lwp_estcpu * ttlticks + estcpu) / 1147 (ttlticks + 1)); 1148 dfly_resetpriority(lp); 1149 lp->lwp_cpbase += ttlticks * gd->gd_schedclock.periodic; 1150 lp->lwp_cpticks = 0; 1151 } 1152 } 1153 1154 /* 1155 * Compute the priority of a process when running in user mode. 1156 * Arrange to reschedule if the resulting priority is better 1157 * than that of the current process. 1158 * 1159 * This routine may be called with any process. 1160 * 1161 * This routine is called by fork1() for initial setup with the process of 1162 * the run queue, and also may be called normally with the process on or 1163 * off the run queue. 1164 */ 1165 static void 1166 dfly_resetpriority(struct lwp *lp) 1167 { 1168 dfly_pcpu_t rdd; 1169 int newpriority; 1170 u_short newrqtype; 1171 int rcpu; 1172 int checkpri; 1173 int estcpu; 1174 int delta_uload; 1175 1176 crit_enter(); 1177 1178 /* 1179 * Lock the scheduler (lp) belongs to. This can be on a different 1180 * cpu. Handle races. This loop breaks out with the appropriate 1181 * rdd locked. 1182 */ 1183 for (;;) { 1184 rcpu = lp->lwp_qcpu; 1185 cpu_ccfence(); 1186 rdd = &dfly_pcpu[rcpu]; 1187 spin_lock(&rdd->spin); 1188 if (rcpu == lp->lwp_qcpu) 1189 break; 1190 spin_unlock(&rdd->spin); 1191 } 1192 1193 /* 1194 * Calculate the new priority and queue type 1195 */ 1196 newrqtype = lp->lwp_rtprio.type; 1197 1198 switch(newrqtype) { 1199 case RTP_PRIO_REALTIME: 1200 case RTP_PRIO_FIFO: 1201 newpriority = PRIBASE_REALTIME + 1202 (lp->lwp_rtprio.prio & PRIMASK); 1203 break; 1204 case RTP_PRIO_NORMAL: 1205 /* 1206 * Calculate the new priority. 1207 * 1208 * nice contributes up to NICE_QS queues (typ 32 - full range) 1209 * estcpu contributes up to EST_QS queues (typ 24) 1210 * 1211 * A nice +20 process receives 1/10 cpu vs nice+0. Niced 1212 * process more than 20 apart may receive no cpu, so cpu 1213 * bound nice -20 can prevent a nice +5 from getting any 1214 * cpu. A nice+0, being in the middle, always gets some cpu 1215 * no matter what. 1216 */ 1217 estcpu = lp->lwp_estcpu; 1218 newpriority = (lp->lwp_proc->p_nice - PRIO_MIN) * 1219 (NICE_QS * PPQ) / PRIO_RANGE; 1220 newpriority += estcpu * PPQ / ESTCPUPPQ; 1221 if (newpriority < 0) 1222 newpriority = 0; 1223 if (newpriority >= MAXPRI) 1224 newpriority = MAXPRI - 1; 1225 newpriority += PRIBASE_NORMAL; 1226 break; 1227 case RTP_PRIO_IDLE: 1228 newpriority = PRIBASE_IDLE + (lp->lwp_rtprio.prio & PRIMASK); 1229 break; 1230 case RTP_PRIO_THREAD: 1231 newpriority = PRIBASE_THREAD + (lp->lwp_rtprio.prio & PRIMASK); 1232 break; 1233 default: 1234 panic("Bad RTP_PRIO %d", newrqtype); 1235 /* NOT REACHED */ 1236 } 1237 1238 /* 1239 * The LWKT scheduler doesn't dive usched structures, give it a hint 1240 * on the relative priority of user threads running in the kernel. 1241 * The LWKT scheduler will always ensure that a user thread running 1242 * in the kernel will get cpu some time, regardless of its upri, 1243 * but can decide not to instantly switch from one kernel or user 1244 * mode user thread to a kernel-mode user thread when it has a less 1245 * desireable user priority. 1246 * 1247 * td_upri has normal sense (higher values are more desireable), so 1248 * negate it (this is a different field lp->lwp_priority) 1249 */ 1250 lp->lwp_thread->td_upri = -(newpriority & usched_dfly_swmask); 1251 1252 /* 1253 * The newpriority incorporates the queue type so do a simple masked 1254 * check to determine if the process has moved to another queue. If 1255 * it has, and it is currently on a run queue, then move it. 1256 * 1257 * Since uload is ~PPQMASK masked, no modifications are necessary if 1258 * we end up in the same run queue. 1259 * 1260 * Reset rrcount if moving to a higher-priority queue, otherwise 1261 * retain rrcount. 1262 */ 1263 if ((lp->lwp_priority ^ newpriority) & ~PPQMASK) { 1264 if (lp->lwp_priority < newpriority) 1265 lp->lwp_rrcount = 0; 1266 if (lp->lwp_mpflags & LWP_MP_ONRUNQ) { 1267 dfly_remrunqueue_locked(rdd, lp); 1268 lp->lwp_priority = newpriority; 1269 lp->lwp_rqtype = newrqtype; 1270 lp->lwp_rqindex = (newpriority & PRIMASK) / PPQ; 1271 dfly_setrunqueue_locked(rdd, lp); 1272 checkpri = 1; 1273 } else { 1274 lp->lwp_priority = newpriority; 1275 lp->lwp_rqtype = newrqtype; 1276 lp->lwp_rqindex = (newpriority & PRIMASK) / PPQ; 1277 checkpri = 0; 1278 } 1279 } else { 1280 /* 1281 * In the same PPQ, uload cannot change. 1282 */ 1283 lp->lwp_priority = newpriority; 1284 checkpri = 1; 1285 rcpu = -1; 1286 } 1287 1288 /* 1289 * Adjust effective load. 1290 * 1291 * Calculate load then scale up or down geometrically based on p_nice. 1292 * Processes niced up (positive) are less important, and processes 1293 * niced downard (negative) are more important. The higher the uload, 1294 * the more important the thread. 1295 */ 1296 /* 0-511, 0-100% cpu */ 1297 delta_uload = lptouload(lp); 1298 delta_uload -= lp->lwp_uload; 1299 if (lp->lwp_uload + delta_uload < -32767) { 1300 delta_uload = -32768 - lp->lwp_uload; 1301 } else if (lp->lwp_uload + delta_uload > 32767) { 1302 delta_uload = 32767 - lp->lwp_uload; 1303 } 1304 lp->lwp_uload += delta_uload; 1305 if (lp->lwp_mpflags & LWP_MP_ULOAD) 1306 atomic_add_long(&dfly_pcpu[lp->lwp_qcpu].uload, delta_uload); 1307 1308 /* 1309 * Determine if we need to reschedule the target cpu. This only 1310 * occurs if the LWP is already on a scheduler queue, which means 1311 * that idle cpu notification has already occured. At most we 1312 * need only issue a need_user_resched() on the appropriate cpu. 1313 * 1314 * The LWP may be owned by a CPU different from the current one, 1315 * in which case dd->uschedcp may be modified without an MP lock 1316 * or a spinlock held. The worst that happens is that the code 1317 * below causes a spurious need_user_resched() on the target CPU 1318 * and dd->pri to be wrong for a short period of time, both of 1319 * which are harmless. 1320 * 1321 * If checkpri is 0 we are adjusting the priority of the current 1322 * process, possibly higher (less desireable), so ignore the upri 1323 * check which will fail in that case. 1324 */ 1325 if (rcpu >= 0) { 1326 if (CPUMASK_TESTBIT(dfly_rdyprocmask, rcpu) && 1327 (checkpri == 0 || 1328 (rdd->upri & ~PRIMASK) > 1329 (lp->lwp_priority & ~PRIMASK))) { 1330 if (rcpu == mycpu->gd_cpuid) { 1331 spin_unlock(&rdd->spin); 1332 need_user_resched(); 1333 } else { 1334 spin_unlock(&rdd->spin); 1335 lwkt_send_ipiq(globaldata_find(rcpu), 1336 dfly_need_user_resched_remote, 1337 NULL); 1338 } 1339 } else { 1340 spin_unlock(&rdd->spin); 1341 } 1342 } else { 1343 spin_unlock(&rdd->spin); 1344 } 1345 crit_exit(); 1346 } 1347 1348 static 1349 void 1350 dfly_yield(struct lwp *lp) 1351 { 1352 if (lp->lwp_qcpu != mycpu->gd_cpuid) 1353 return; 1354 KKASSERT(lp == curthread->td_lwp); 1355 1356 /* 1357 * Don't set need_user_resched() or mess with rrcount or anything. 1358 * the TDF flag will override everything as long as we release. 1359 */ 1360 atomic_set_int(&lp->lwp_thread->td_mpflags, TDF_MP_DIDYIELD); 1361 dfly_release_curproc(lp); 1362 } 1363 1364 /* 1365 * Thread was forcefully migrated to another cpu. Normally forced migrations 1366 * are used for iterations and the kernel returns to the original cpu before 1367 * returning and this is not needed. However, if the kernel migrates a 1368 * thread to another cpu and wants to leave it there, it has to call this 1369 * scheduler helper. 1370 * 1371 * Note that the lwkt_migratecpu() function also released the thread, so 1372 * we don't have to worry about that. 1373 */ 1374 static 1375 void 1376 dfly_changedcpu(struct lwp *lp) 1377 { 1378 dfly_pcpu_t dd = &dfly_pcpu[lp->lwp_qcpu]; 1379 dfly_pcpu_t rdd = &dfly_pcpu[mycpu->gd_cpuid]; 1380 1381 if (dd != rdd) { 1382 spin_lock(&dd->spin); 1383 dfly_changeqcpu_locked(lp, dd, rdd); 1384 spin_unlock(&dd->spin); 1385 } 1386 } 1387 1388 /* 1389 * Called from fork1() when a new child process is being created. 1390 * 1391 * Give the child process an initial estcpu that is more batch then 1392 * its parent and dock the parent for the fork (but do not 1393 * reschedule the parent). 1394 * 1395 * fast 1396 * 1397 * XXX lwp should be "spawning" instead of "forking" 1398 */ 1399 static void 1400 dfly_forking(struct lwp *plp, struct lwp *lp) 1401 { 1402 int estcpu; 1403 1404 /* 1405 * Put the child 4 queue slots (out of 32) higher than the parent 1406 * (less desireable than the parent). 1407 */ 1408 lp->lwp_estcpu = ESTCPULIM(plp->lwp_estcpu + 1409 ESTCPUPPQ * usched_dfly_forkbias); 1410 lp->lwp_forked = 1; 1411 lp->lwp_estfast = 0; 1412 1413 /* 1414 * Even though the lp will be scheduled specially the first time 1415 * due to lp->lwp_forked, it is important to initialize lwp_qcpu 1416 * to avoid favoring a fixed cpu. 1417 */ 1418 #if 0 1419 static uint16_t save_cpu; 1420 lp->lwp_qcpu = ++save_cpu % ncpus; 1421 #else 1422 lp->lwp_qcpu = plp->lwp_qcpu; 1423 if (CPUMASK_TESTBIT(lp->lwp_cpumask, lp->lwp_qcpu) == 0) 1424 lp->lwp_qcpu = BSFCPUMASK(lp->lwp_cpumask); 1425 #endif 1426 1427 /* 1428 * Dock the parent a cost for the fork, protecting us from fork 1429 * bombs. If the parent is forking quickly this makes both the 1430 * parent and child more batchy. 1431 */ 1432 estcpu = plp->lwp_estcpu + ESTCPUPPQ / 16; 1433 plp->lwp_estcpu = ESTCPULIM(estcpu); 1434 } 1435 1436 /* 1437 * Called when a lwp is being removed from this scheduler, typically 1438 * during lwp_exit(). We have to clean out any ULOAD accounting before 1439 * we can let the lp go. The dd->spin lock is not needed for uload 1440 * updates. 1441 * 1442 * Scheduler dequeueing has already occurred, no further action in that 1443 * regard is needed. 1444 */ 1445 static void 1446 dfly_exiting(struct lwp *lp, struct proc *child_proc) 1447 { 1448 dfly_pcpu_t dd = &dfly_pcpu[lp->lwp_qcpu]; 1449 1450 if (lp->lwp_mpflags & LWP_MP_ULOAD) { 1451 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ULOAD); 1452 atomic_add_long(&dd->uload, -lp->lwp_uload); 1453 atomic_add_int(&dd->ucount, -1); 1454 } 1455 } 1456 1457 /* 1458 * This function cannot block in any way, but spinlocks are ok. 1459 * 1460 * Update the uload based on the state of the thread (whether it is going 1461 * to sleep or running again). The uload is meant to be a longer-term 1462 * load and not an instantanious load. 1463 */ 1464 static void 1465 dfly_uload_update(struct lwp *lp) 1466 { 1467 dfly_pcpu_t dd = &dfly_pcpu[lp->lwp_qcpu]; 1468 1469 if (lp->lwp_thread->td_flags & TDF_RUNQ) { 1470 if ((lp->lwp_mpflags & LWP_MP_ULOAD) == 0) { 1471 spin_lock(&dd->spin); 1472 if ((lp->lwp_mpflags & LWP_MP_ULOAD) == 0) { 1473 atomic_set_int(&lp->lwp_mpflags, 1474 LWP_MP_ULOAD); 1475 atomic_add_long(&dd->uload, lp->lwp_uload); 1476 atomic_add_int(&dd->ucount, 1); 1477 } 1478 spin_unlock(&dd->spin); 1479 } 1480 } else if (lp->lwp_slptime > 0) { 1481 if (lp->lwp_mpflags & LWP_MP_ULOAD) { 1482 spin_lock(&dd->spin); 1483 if (lp->lwp_mpflags & LWP_MP_ULOAD) { 1484 atomic_clear_int(&lp->lwp_mpflags, 1485 LWP_MP_ULOAD); 1486 atomic_add_long(&dd->uload, -lp->lwp_uload); 1487 atomic_add_int(&dd->ucount, -1); 1488 } 1489 spin_unlock(&dd->spin); 1490 } 1491 } 1492 } 1493 1494 /* 1495 * chooseproc() is called when a cpu needs a user process to LWKT schedule, 1496 * it selects a user process and returns it. If chklp is non-NULL and chklp 1497 * has a better or equal priority then the process that would otherwise be 1498 * chosen, NULL is returned. 1499 * 1500 * Until we fix the RUNQ code the chklp test has to be strict or we may 1501 * bounce between processes trying to acquire the current process designation. 1502 * 1503 * Must be called with rdd->spin locked. The spinlock is left intact through 1504 * the entire routine. dd->spin does not have to be locked. 1505 * 1506 * If worst is non-zero this function finds the worst thread instead of the 1507 * best thread (used by the schedulerclock-based rover). 1508 */ 1509 static 1510 struct lwp * 1511 dfly_chooseproc_locked(dfly_pcpu_t rdd, dfly_pcpu_t dd, 1512 struct lwp *chklp, int worst) 1513 { 1514 struct lwp *lp; 1515 struct rq *q; 1516 u_int32_t *which; 1517 u_int32_t pri; 1518 u_int32_t rtqbits; 1519 u_int32_t tsqbits; 1520 u_int32_t idqbits; 1521 1522 /* 1523 * Select best or worst process. Once selected, clear the bit 1524 * in our local variable (idqbits, tsqbits, or rtqbits) just 1525 * in case we have to loop. 1526 */ 1527 rtqbits = rdd->rtqueuebits; 1528 tsqbits = rdd->queuebits; 1529 idqbits = rdd->idqueuebits; 1530 1531 loopfar: 1532 if (worst) { 1533 if (idqbits) { 1534 pri = bsrl(idqbits); 1535 idqbits &= ~(1U << pri); 1536 q = &rdd->idqueues[pri]; 1537 which = &rdd->idqueuebits; 1538 } else if (tsqbits) { 1539 pri = bsrl(tsqbits); 1540 tsqbits &= ~(1U << pri); 1541 q = &rdd->queues[pri]; 1542 which = &rdd->queuebits; 1543 } else if (rtqbits) { 1544 pri = bsrl(rtqbits); 1545 rtqbits &= ~(1U << pri); 1546 q = &rdd->rtqueues[pri]; 1547 which = &rdd->rtqueuebits; 1548 } else { 1549 return (NULL); 1550 } 1551 lp = TAILQ_LAST(q, rq); 1552 } else { 1553 if (rtqbits) { 1554 pri = bsfl(rtqbits); 1555 rtqbits &= ~(1U << pri); 1556 q = &rdd->rtqueues[pri]; 1557 which = &rdd->rtqueuebits; 1558 } else if (tsqbits) { 1559 pri = bsfl(tsqbits); 1560 tsqbits &= ~(1U << pri); 1561 q = &rdd->queues[pri]; 1562 which = &rdd->queuebits; 1563 } else if (idqbits) { 1564 pri = bsfl(idqbits); 1565 idqbits &= ~(1U << pri); 1566 q = &rdd->idqueues[pri]; 1567 which = &rdd->idqueuebits; 1568 } else { 1569 return (NULL); 1570 } 1571 lp = TAILQ_FIRST(q); 1572 } 1573 KASSERT(lp, ("chooseproc: no lwp on busy queue")); 1574 1575 loopnear: 1576 /* 1577 * If the passed lwp <chklp> is reasonably close to the selected 1578 * lwp <lp>, return NULL (indicating that <chklp> should be kept). 1579 * 1580 * Note that we must error on the side of <chklp> to avoid bouncing 1581 * between threads in the acquire code. 1582 */ 1583 if (chklp) { 1584 if (chklp->lwp_priority < lp->lwp_priority + PPQ) 1585 return(NULL); 1586 } 1587 1588 /* 1589 * When rdd != dd, we have to make sure that the process we 1590 * are pulling is allow to run on our cpu. This alternative 1591 * path is a bit more expensive but its not considered to be 1592 * in the critical path. 1593 */ 1594 if (rdd != dd && CPUMASK_TESTBIT(lp->lwp_cpumask, dd->cpuid) == 0) { 1595 if (worst) 1596 lp = TAILQ_PREV(lp, rq, lwp_procq); 1597 else 1598 lp = TAILQ_NEXT(lp, lwp_procq); 1599 if (lp) 1600 goto loopnear; 1601 goto loopfar; 1602 } 1603 1604 KTR_COND_LOG(usched_chooseproc, 1605 lp->lwp_proc->p_pid == usched_dfly_pid_debug, 1606 lp->lwp_proc->p_pid, 1607 lp->lwp_thread->td_gd->gd_cpuid, 1608 mycpu->gd_cpuid); 1609 1610 KASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) != 0, ("not on runq6!")); 1611 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); 1612 TAILQ_REMOVE(q, lp, lwp_procq); 1613 --rdd->runqcount; 1614 if (TAILQ_EMPTY(q)) 1615 *which &= ~(1 << pri); 1616 1617 /* 1618 * If we are choosing a process from rdd with the intent to 1619 * move it to dd, lwp_qcpu must be adjusted while rdd's spinlock 1620 * is still held. 1621 */ 1622 if (rdd != dd) { 1623 if (lp->lwp_mpflags & LWP_MP_ULOAD) { 1624 atomic_add_long(&rdd->uload, -lp->lwp_uload); 1625 atomic_add_int(&rdd->ucount, -1); 1626 } 1627 lp->lwp_qcpu = dd->cpuid; 1628 atomic_add_long(&dd->uload, lp->lwp_uload); 1629 atomic_add_int(&dd->ucount, 1); 1630 atomic_set_int(&lp->lwp_mpflags, LWP_MP_ULOAD); 1631 } 1632 return lp; 1633 } 1634 1635 /* 1636 * USED TO PUSH RUNNABLE LWPS TO THE LEAST LOADED CPU. 1637 * 1638 * Choose a cpu node to schedule lp on, hopefully nearby its current 1639 * node. 1640 * 1641 * We give the current node a modest advantage for obvious reasons. 1642 * 1643 * We also give the node the thread was woken up FROM a slight advantage 1644 * in order to try to schedule paired threads which synchronize/block waiting 1645 * for each other fairly close to each other. Similarly in a network setting 1646 * this feature will also attempt to place a user process near the kernel 1647 * protocol thread that is feeding it data. THIS IS A CRITICAL PART of the 1648 * algorithm as it heuristically groups synchronizing processes for locality 1649 * of reference in multi-socket systems. 1650 * 1651 * We check against running processes and give a big advantage if there 1652 * are none running. 1653 * 1654 * The caller will normally dfly_setrunqueue() lp on the returned queue. 1655 * 1656 * When the topology is known choose a cpu whos group has, in aggregate, 1657 * has the lowest weighted load. 1658 */ 1659 static 1660 dfly_pcpu_t 1661 dfly_choose_best_queue(struct lwp *lp) 1662 { 1663 cpumask_t wakemask; 1664 cpumask_t mask; 1665 cpu_node_t *cpup; 1666 cpu_node_t *cpun; 1667 cpu_node_t *cpub; 1668 dfly_pcpu_t dd = &dfly_pcpu[lp->lwp_qcpu]; 1669 dfly_pcpu_t rdd; 1670 int wakecpu; 1671 int cpuid; 1672 int n; 1673 int loadav; 1674 long load; 1675 long lowest_load; 1676 1677 /* 1678 * When the topology is unknown choose a random cpu that is hopefully 1679 * idle. 1680 */ 1681 if (dd->cpunode == NULL) 1682 return (dfly_choose_queue_simple(dd, lp)); 1683 1684 loadav = (averunnable.ldavg[0] + FSCALE / 2) >> FSHIFT; 1685 1686 /* 1687 * Pairing mask 1688 */ 1689 if ((wakecpu = lp->lwp_thread->td_wakefromcpu) >= 0) 1690 wakemask = dfly_pcpu[wakecpu].cpumask; 1691 else 1692 CPUMASK_ASSZERO(wakemask); 1693 1694 if (usched_dfly_debug == lp->lwp_proc->p_pid) 1695 kprintf("choosebest wakefromcpu %d:\n", 1696 lp->lwp_thread->td_wakefromcpu); 1697 1698 /* 1699 * When the topology is known choose a cpu whos group has, in 1700 * aggregate, has the lowest weighted load. 1701 */ 1702 cpup = root_cpu_node; 1703 rdd = dd; 1704 1705 while (cpup) { 1706 /* 1707 * Degenerate case super-root 1708 */ 1709 if (cpup->child_no == 1) { 1710 cpup = cpup->child_node[0]; 1711 continue; 1712 } 1713 1714 /* 1715 * Terminal cpunode 1716 */ 1717 if (cpup->child_no == 0) { 1718 rdd = &dfly_pcpu[BSFCPUMASK(cpup->members)]; 1719 if (usched_dfly_debug == lp->lwp_proc->p_pid) 1720 kprintf(" last cpu %d\n", rdd->cpuid); 1721 break; 1722 } 1723 1724 cpub = NULL; 1725 lowest_load = 0x7FFFFFFFFFFFFFFFLL; 1726 if (usched_dfly_debug == lp->lwp_proc->p_pid) 1727 kprintf(" reset lowest_load for scan\n"); 1728 1729 for (n = 0; n < cpup->child_no; ++n) { 1730 /* 1731 * Accumulate load information for all cpus 1732 * which are members of this node. 1733 */ 1734 int count; 1735 1736 cpun = cpup->child_node[n]; 1737 mask = cpun->members; 1738 CPUMASK_ANDMASK(mask, usched_global_cpumask); 1739 CPUMASK_ANDMASK(mask, smp_active_mask); 1740 CPUMASK_ANDMASK(mask, lp->lwp_cpumask); 1741 if (CPUMASK_TESTZERO(mask)) 1742 continue; 1743 1744 load = 0; 1745 count = 0; 1746 1747 if (usched_dfly_debug == lp->lwp_proc->p_pid) 1748 kprintf(" mask:"); 1749 while (CPUMASK_TESTNZERO(mask)) { 1750 cpuid = BSFCPUMASK(mask); 1751 rdd = &dfly_pcpu[cpuid]; 1752 1753 if (usched_dfly_debug == lp->lwp_proc->p_pid) 1754 kprintf(" %d", cpuid); 1755 1756 /* 1757 * Cumulative load for members. Note that 1758 * if (lp) is part of the group, lp's 1759 * contribution will be backed out later. 1760 */ 1761 load += rdd->uload; 1762 load += rdd->ucount * 1763 usched_dfly_weight3; 1764 1765 /* 1766 * If the node is running a less important 1767 * thread than our thread, give it an 1768 * advantage. Witha high-enough weighting 1769 * this can override most other considerations 1770 * to provide ultimate priority fairness at 1771 * the cost of localization. 1772 */ 1773 if ((rdd->upri & ~PPQMASK) > 1774 (lp->lwp_priority & ~PPQMASK)) { 1775 load -= usched_dfly_weight4; 1776 } 1777 1778 #if 0 1779 if (rdd->uschedcp == NULL && 1780 rdd->runqcount == 0 && 1781 rdd->gd->gd_tdrunqcount == 0 1782 ) { 1783 load += rdd->uload / 2; 1784 load += rdd->ucount * 1785 usched_dfly_weight3 / 2; 1786 } else { 1787 load += rdd->uload; 1788 load += rdd->ucount * 1789 usched_dfly_weight3; 1790 } 1791 #endif 1792 CPUMASK_NANDBIT(mask, cpuid); 1793 ++count; 1794 } 1795 1796 /* 1797 * Compensate if the lp is already accounted for in 1798 * the aggregate uload for this mask set. We want 1799 * to calculate the loads as if lp were not present, 1800 * otherwise the calculation is bogus. 1801 */ 1802 if ((lp->lwp_mpflags & LWP_MP_ULOAD) && 1803 CPUMASK_TESTMASK(dd->cpumask, cpun->members)) { 1804 load -= lp->lwp_uload; 1805 load -= usched_dfly_weight3; /* ucount */ 1806 } 1807 1808 if (usched_dfly_debug == lp->lwp_proc->p_pid) 1809 kprintf("\n accum_start c=%d ld=%ld " 1810 "cpu=%d ld/cnt=%ld ", 1811 count, load, rdd->cpuid, 1812 load / count); 1813 1814 /* 1815 * load is the aggregate load of count CPUs in the 1816 * group. For the weightings to work as intended, 1817 * we want an average per-cpu load. 1818 */ 1819 load = load / count; 1820 1821 /* 1822 * Advantage the cpu group (lp) is already on. 1823 */ 1824 if (CPUMASK_TESTMASK(cpun->members, dd->cpumask)) 1825 load -= usched_dfly_weight1; 1826 1827 if (usched_dfly_debug == lp->lwp_proc->p_pid) 1828 kprintf("B:%ld ", load); 1829 1830 /* 1831 * Advantage nodes with more memory 1832 */ 1833 if (usched_dfly_node_mem) { 1834 load -= cpun->phys_mem * usched_dfly_weight5 / 1835 usched_dfly_node_mem; 1836 } 1837 1838 if (usched_dfly_debug == lp->lwp_proc->p_pid) 1839 kprintf("C:%ld ", load); 1840 1841 /* 1842 * Advantage the cpu group we desire to pair (lp) 1843 * to, but Disadvantage hyperthreads on the same 1844 * core, or the same thread as the ipc peer. 1845 * 1846 * Under very heavy loads it is usually beneficial 1847 * to set kern.usched_dfly.ipc_smt to 1, and under 1848 * extreme loads it might be beneficial to also set 1849 * kern.usched_dfly.ipc_same to 1. 1850 * 1851 * load+ disadvantage 1852 * load- advantage 1853 */ 1854 if (CPUMASK_TESTMASK(cpun->members, wakemask)) { 1855 if (cpun->child_no) { 1856 if (cpun->type == CORE_LEVEL && 1857 usched_dfly_ipc_smt < 0 && 1858 loadav >= (ncpus >> 1)) { 1859 /* 1860 * Advantage at higher levels 1861 * of the topology. 1862 */ 1863 load -= usched_dfly_weight2; 1864 } else if (cpun->type == CORE_LEVEL && 1865 usched_dfly_ipc_smt == 0) { 1866 /* 1867 * Disadvantage the same core 1868 * when there are hyperthreads. 1869 */ 1870 load += usched_dfly_weight2; 1871 } else { 1872 /* 1873 * Advantage at higher levels 1874 * of the topology. 1875 */ 1876 load -= usched_dfly_weight2; 1877 } 1878 } else { 1879 /* 1880 * Disadvantage the last level (core 1881 * or hyperthread). Try to schedule 1882 * the ipc 1883 */ 1884 if (usched_dfly_ipc_same < 0 && 1885 loadav >= ncpus) { 1886 load -= usched_dfly_weight2; 1887 } else if (usched_dfly_ipc_same) { 1888 load -= usched_dfly_weight2; 1889 } else { 1890 load += usched_dfly_weight2; 1891 } 1892 } 1893 #if 0 1894 if (cpun->child_no != 0) { 1895 /* advantage */ 1896 load -= usched_dfly_weight2; 1897 } else { 1898 /* 1899 * 0x10 (disadvantage) 1900 * 0x00 (advantage) - default 1901 */ 1902 if (usched_dfly_features & 0x10) 1903 load += usched_dfly_weight2; 1904 else 1905 load -= usched_dfly_weight2; 1906 } 1907 #endif 1908 } 1909 1910 if (usched_dfly_debug == lp->lwp_proc->p_pid) 1911 kprintf("D:%ld ", load); 1912 1913 /* 1914 * Calculate the best load 1915 */ 1916 if (cpub == NULL || lowest_load > load || 1917 (lowest_load == load && 1918 CPUMASK_TESTMASK(cpun->members, dd->cpumask)) 1919 ) { 1920 lowest_load = load; 1921 cpub = cpun; 1922 } 1923 1924 if (usched_dfly_debug == lp->lwp_proc->p_pid) 1925 kprintf("low=%ld]\n", lowest_load); 1926 } 1927 cpup = cpub; 1928 } 1929 /* Dispatch this outcast to a proper CPU. */ 1930 if (__predict_false(CPUMASK_TESTBIT(lp->lwp_cpumask, rdd->cpuid) == 0)) 1931 rdd = &dfly_pcpu[BSFCPUMASK(lp->lwp_cpumask)]; 1932 if (usched_dfly_chooser > 0) { 1933 --usched_dfly_chooser; /* only N lines */ 1934 kprintf("lp %02d->%02d %s\n", 1935 lp->lwp_qcpu, rdd->cpuid, lp->lwp_proc->p_comm); 1936 } 1937 if (usched_dfly_debug == lp->lwp_proc->p_pid) 1938 kprintf("final cpu %d\n", rdd->cpuid); 1939 return (rdd); 1940 } 1941 1942 /* 1943 * USED TO PULL RUNNABLE LWPS FROM THE MOST LOADED CPU. 1944 * 1945 * Choose the worst queue close to dd's cpu node with a non-empty runq 1946 * that is NOT dd. 1947 * 1948 * This is used by the thread chooser when the current cpu's queues are 1949 * empty to steal a thread from another cpu's queue. We want to offload 1950 * the most heavily-loaded queue. 1951 * 1952 * However, we do not want to steal from far-away nodes who themselves 1953 * have idle cpu's that are more suitable to distribute the far-away 1954 * thread to. 1955 */ 1956 static 1957 dfly_pcpu_t 1958 dfly_choose_worst_queue(dfly_pcpu_t dd, int forceit) 1959 { 1960 cpumask_t mask; 1961 cpu_node_t *cpup; 1962 cpu_node_t *cpun; 1963 cpu_node_t *cpub; 1964 dfly_pcpu_t rdd; 1965 int cpuid; 1966 int n; 1967 long load; 1968 long highest_load; 1969 #if 0 1970 int pri; 1971 int hpri; 1972 #endif 1973 1974 /* 1975 * When the topology is unknown choose a random cpu that is hopefully 1976 * idle. 1977 */ 1978 if (dd->cpunode == NULL) { 1979 return (NULL); 1980 } 1981 1982 /* 1983 * When the topology is known choose a cpu whos group has, in 1984 * aggregate, has the highest weighted load. 1985 */ 1986 cpup = root_cpu_node; 1987 rdd = dd; 1988 while (cpup) { 1989 /* 1990 * Degenerate case super-root 1991 */ 1992 if (cpup->child_no == 1) { 1993 cpup = cpup->child_node[0]; 1994 continue; 1995 } 1996 1997 /* 1998 * Terminal cpunode 1999 */ 2000 if (cpup->child_no == 0) { 2001 rdd = &dfly_pcpu[BSFCPUMASK(cpup->members)]; 2002 break; 2003 } 2004 2005 cpub = NULL; 2006 highest_load = -0x7FFFFFFFFFFFFFFFLL; 2007 2008 for (n = 0; n < cpup->child_no; ++n) { 2009 /* 2010 * Accumulate load information for all cpus 2011 * which are members of this node. 2012 */ 2013 int count; 2014 2015 cpun = cpup->child_node[n]; 2016 mask = cpun->members; 2017 CPUMASK_ANDMASK(mask, usched_global_cpumask); 2018 CPUMASK_ANDMASK(mask, smp_active_mask); 2019 if (CPUMASK_TESTZERO(mask)) 2020 continue; 2021 2022 load = 0; 2023 count = 0; 2024 2025 while (CPUMASK_TESTNZERO(mask)) { 2026 cpuid = BSFCPUMASK(mask); 2027 rdd = &dfly_pcpu[cpuid]; 2028 2029 load += rdd->uload; 2030 load += rdd->ucount * usched_dfly_weight3; 2031 2032 #if 0 2033 if (rdd->uschedcp == NULL && 2034 rdd->runqcount == 0 && 2035 rdd->gd->gd_tdrunqcount == 0 2036 ) { 2037 load += rdd->uload / 2; 2038 load += rdd->ucount * 2039 usched_dfly_weight3 / 2; 2040 } else { 2041 load += rdd->uload; 2042 load += rdd->ucount * 2043 usched_dfly_weight3; 2044 } 2045 #endif 2046 CPUMASK_NANDBIT(mask, cpuid); 2047 ++count; 2048 } 2049 load /= count; 2050 2051 /* 2052 * Advantage the cpu group (dd) is already on. 2053 * 2054 * When choosing the worst queue we reverse the 2055 * sign, but only count half the weight. 2056 * 2057 * weight1 needs to be high enough to be stable, 2058 * but this can also cause it to be too sticky, 2059 * so the iterator which rebalances the load sets 2060 * forceit to ignore it. 2061 */ 2062 if (forceit == 0 && 2063 CPUMASK_TESTMASK(dd->cpumask, cpun->members)) { 2064 load += usched_dfly_weight1 / 2; 2065 } 2066 2067 /* 2068 * Disadvantage nodes with more memory (same sign). 2069 */ 2070 if (usched_dfly_node_mem) { 2071 load -= cpun->phys_mem * usched_dfly_weight5 / 2072 usched_dfly_node_mem; 2073 } 2074 2075 2076 /* 2077 * The best candidate is the one with the worst 2078 * (highest) load. 2079 */ 2080 if (cpub == NULL || highest_load < load || 2081 (highest_load == load && 2082 CPUMASK_TESTMASK(cpun->members, dd->cpumask))) { 2083 highest_load = load; 2084 cpub = cpun; 2085 } 2086 } 2087 cpup = cpub; 2088 } 2089 2090 /* 2091 * We never return our own node (dd), and only return a remote 2092 * node if it's load is significantly worse than ours (i.e. where 2093 * stealing a thread would be considered reasonable). 2094 * 2095 * This also helps us avoid breaking paired threads apart which 2096 * can have disastrous effects on performance. 2097 */ 2098 if (rdd == dd) 2099 return(NULL); 2100 2101 #if 0 2102 hpri = 0; 2103 if (rdd->rtqueuebits && hpri < (pri = bsrl(rdd->rtqueuebits))) 2104 hpri = pri; 2105 if (rdd->queuebits && hpri < (pri = bsrl(rdd->queuebits))) 2106 hpri = pri; 2107 if (rdd->idqueuebits && hpri < (pri = bsrl(rdd->idqueuebits))) 2108 hpri = pri; 2109 hpri *= PPQ; 2110 if (rdd->uload - hpri < dd->uload + hpri) 2111 return(NULL); 2112 #endif 2113 return (rdd); 2114 } 2115 2116 static 2117 dfly_pcpu_t 2118 dfly_choose_queue_simple(dfly_pcpu_t dd, struct lwp *lp) 2119 { 2120 dfly_pcpu_t rdd; 2121 cpumask_t tmpmask; 2122 cpumask_t mask; 2123 int cpubase; 2124 int cpuid; 2125 2126 /* 2127 * Fallback to the original heuristic, select random cpu, 2128 * first checking the cpus not currently running a user thread. 2129 * 2130 * Use cpuid as the base cpu in our scan, first checking 2131 * cpuid...(ncpus-1), then 0...(cpuid-1). This avoid favoring 2132 * lower-numbered cpus. 2133 */ 2134 ++dd->scancpu; /* SMP race ok */ 2135 mask = dfly_rdyprocmask; 2136 CPUMASK_NANDMASK(mask, dfly_curprocmask); 2137 CPUMASK_ANDMASK(mask, lp->lwp_cpumask); 2138 CPUMASK_ANDMASK(mask, smp_active_mask); 2139 CPUMASK_ANDMASK(mask, usched_global_cpumask); 2140 2141 cpubase = (int)(dd->scancpu % ncpus); 2142 CPUMASK_ASSBMASK(tmpmask, cpubase); 2143 CPUMASK_INVMASK(tmpmask); 2144 CPUMASK_ANDMASK(tmpmask, mask); 2145 while (CPUMASK_TESTNZERO(tmpmask)) { 2146 cpuid = BSFCPUMASK(tmpmask); 2147 rdd = &dfly_pcpu[cpuid]; 2148 2149 if ((rdd->upri & ~PPQMASK) >= (lp->lwp_priority & ~PPQMASK)) 2150 goto found; 2151 CPUMASK_NANDBIT(tmpmask, cpuid); 2152 } 2153 2154 CPUMASK_ASSBMASK(tmpmask, cpubase); 2155 CPUMASK_ANDMASK(tmpmask, mask); 2156 while (CPUMASK_TESTNZERO(tmpmask)) { 2157 cpuid = BSFCPUMASK(tmpmask); 2158 rdd = &dfly_pcpu[cpuid]; 2159 2160 if ((rdd->upri & ~PPQMASK) >= (lp->lwp_priority & ~PPQMASK)) 2161 goto found; 2162 CPUMASK_NANDBIT(tmpmask, cpuid); 2163 } 2164 2165 /* 2166 * Then cpus which might have a currently running lp 2167 */ 2168 mask = dfly_rdyprocmask; 2169 CPUMASK_ANDMASK(mask, dfly_curprocmask); 2170 CPUMASK_ANDMASK(mask, lp->lwp_cpumask); 2171 CPUMASK_ANDMASK(mask, smp_active_mask); 2172 CPUMASK_ANDMASK(mask, usched_global_cpumask); 2173 2174 CPUMASK_ASSBMASK(tmpmask, cpubase); 2175 CPUMASK_INVMASK(tmpmask); 2176 CPUMASK_ANDMASK(tmpmask, mask); 2177 while (CPUMASK_TESTNZERO(tmpmask)) { 2178 cpuid = BSFCPUMASK(tmpmask); 2179 rdd = &dfly_pcpu[cpuid]; 2180 2181 if ((rdd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) 2182 goto found; 2183 CPUMASK_NANDBIT(tmpmask, cpuid); 2184 } 2185 2186 CPUMASK_ASSBMASK(tmpmask, cpubase); 2187 CPUMASK_ANDMASK(tmpmask, mask); 2188 while (CPUMASK_TESTNZERO(tmpmask)) { 2189 cpuid = BSFCPUMASK(tmpmask); 2190 rdd = &dfly_pcpu[cpuid]; 2191 2192 if ((rdd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) 2193 goto found; 2194 CPUMASK_NANDBIT(tmpmask, cpuid); 2195 } 2196 2197 /* 2198 * If we cannot find a suitable cpu we round-robin using scancpu. 2199 * Other cpus will pickup as they release their current lwps or 2200 * become ready. 2201 * 2202 * Avoid a degenerate system lockup case if usched_global_cpumask 2203 * is set to 0 or otherwise does not cover lwp_cpumask. 2204 * 2205 * We only kick the target helper thread in this case, we do not 2206 * set the user resched flag because 2207 */ 2208 cpuid = cpubase; 2209 if (CPUMASK_TESTBIT(lp->lwp_cpumask, cpuid) == 0) 2210 cpuid = BSFCPUMASK(lp->lwp_cpumask); 2211 else if (CPUMASK_TESTBIT(usched_global_cpumask, cpuid) == 0) 2212 cpuid = 0; 2213 rdd = &dfly_pcpu[cpuid]; 2214 found: 2215 return (rdd); 2216 } 2217 2218 static 2219 void 2220 dfly_need_user_resched_remote(void *dummy) 2221 { 2222 globaldata_t gd = mycpu; 2223 dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid]; 2224 2225 /* 2226 * Flag reschedule needed 2227 */ 2228 need_user_resched(); 2229 2230 /* 2231 * If no user thread is currently running we need to kick the helper 2232 * on our cpu to recover. Otherwise the cpu will never schedule 2233 * anything again. 2234 * 2235 * We cannot schedule the process ourselves because this is an 2236 * IPI callback and we cannot acquire spinlocks in an IPI callback. 2237 * 2238 * Call wakeup_mycpu to avoid sending IPIs to other CPUs 2239 */ 2240 if (dd->uschedcp == NULL && (dd->flags & DFLY_PCPU_RDYMASK)) { 2241 ATOMIC_CPUMASK_NANDBIT(dfly_rdyprocmask, gd->gd_cpuid); 2242 dd->flags &= ~DFLY_PCPU_RDYMASK; 2243 wakeup_mycpu(dd->helper_thread); 2244 } 2245 } 2246 2247 /* 2248 * dfly_remrunqueue_locked() removes a given process from the run queue 2249 * that it is on, clearing the queue busy bit if it becomes empty. 2250 * 2251 * Note that user process scheduler is different from the LWKT schedule. 2252 * The user process scheduler only manages user processes but it uses LWKT 2253 * underneath, and a user process operating in the kernel will often be 2254 * 'released' from our management. 2255 * 2256 * uload is NOT adjusted here. It is only adjusted if the lwkt_thread goes 2257 * to sleep or the lwp is moved to a different runq. 2258 */ 2259 static void 2260 dfly_remrunqueue_locked(dfly_pcpu_t rdd, struct lwp *lp) 2261 { 2262 struct rq *q; 2263 u_int32_t *which; 2264 u_int8_t pri; 2265 2266 KKASSERT(rdd->runqcount >= 0); 2267 2268 pri = lp->lwp_rqindex; 2269 2270 switch(lp->lwp_rqtype) { 2271 case RTP_PRIO_NORMAL: 2272 q = &rdd->queues[pri]; 2273 which = &rdd->queuebits; 2274 break; 2275 case RTP_PRIO_REALTIME: 2276 case RTP_PRIO_FIFO: 2277 q = &rdd->rtqueues[pri]; 2278 which = &rdd->rtqueuebits; 2279 break; 2280 case RTP_PRIO_IDLE: 2281 q = &rdd->idqueues[pri]; 2282 which = &rdd->idqueuebits; 2283 break; 2284 default: 2285 panic("remrunqueue: invalid rtprio type"); 2286 /* NOT REACHED */ 2287 } 2288 KKASSERT(lp->lwp_mpflags & LWP_MP_ONRUNQ); 2289 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); 2290 TAILQ_REMOVE(q, lp, lwp_procq); 2291 --rdd->runqcount; 2292 if (TAILQ_EMPTY(q)) { 2293 KASSERT((*which & (1 << pri)) != 0, 2294 ("remrunqueue: remove from empty queue")); 2295 *which &= ~(1 << pri); 2296 } 2297 } 2298 2299 /* 2300 * dfly_setrunqueue_locked() 2301 * 2302 * Add a process whos rqtype and rqindex had previously been calculated 2303 * onto the appropriate run queue. Determine if the addition requires 2304 * a reschedule on a cpu and return the cpuid or -1. 2305 * 2306 * NOTE: Lower priorities are better priorities. 2307 * 2308 * NOTE ON ULOAD: This variable specifies the aggregate load on a cpu, the 2309 * sum of the rough lwp_priority for all running and runnable 2310 * processes. Lower priority processes (higher lwp_priority 2311 * values) actually DO count as more load, not less, because 2312 * these are the programs which require the most care with 2313 * regards to cpu selection. 2314 */ 2315 static void 2316 dfly_setrunqueue_locked(dfly_pcpu_t rdd, struct lwp *lp) 2317 { 2318 u_int32_t *which; 2319 struct rq *q; 2320 int pri; 2321 2322 KKASSERT(lp->lwp_qcpu == rdd->cpuid); 2323 2324 if ((lp->lwp_mpflags & LWP_MP_ULOAD) == 0) { 2325 atomic_set_int(&lp->lwp_mpflags, LWP_MP_ULOAD); 2326 atomic_add_long(&rdd->uload, lp->lwp_uload); 2327 atomic_add_int(&rdd->ucount, 1); 2328 } 2329 2330 pri = lp->lwp_rqindex; 2331 2332 switch(lp->lwp_rqtype) { 2333 case RTP_PRIO_NORMAL: 2334 q = &rdd->queues[pri]; 2335 which = &rdd->queuebits; 2336 break; 2337 case RTP_PRIO_REALTIME: 2338 case RTP_PRIO_FIFO: 2339 q = &rdd->rtqueues[pri]; 2340 which = &rdd->rtqueuebits; 2341 break; 2342 case RTP_PRIO_IDLE: 2343 q = &rdd->idqueues[pri]; 2344 which = &rdd->idqueuebits; 2345 break; 2346 default: 2347 panic("remrunqueue: invalid rtprio type"); 2348 /* NOT REACHED */ 2349 } 2350 2351 /* 2352 * Place us on the selected queue. Determine if we should be 2353 * placed at the head of the queue or at the end. 2354 * 2355 * We are placed at the tail if our round-robin count has expired, 2356 * or is about to expire and the system thinks its a good place to 2357 * round-robin, or there is already a next thread on the queue 2358 * (it might be trying to pick up where it left off and we don't 2359 * want to interfere). 2360 */ 2361 KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); 2362 atomic_set_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); 2363 ++rdd->runqcount; 2364 2365 if (lp->lwp_rrcount >= usched_dfly_rrinterval || 2366 (lp->lwp_rrcount >= usched_dfly_rrinterval / 2 && 2367 (lp->lwp_thread->td_mpflags & TDF_MP_BATCH_DEMARC)) 2368 ) { 2369 /* 2370 * Place on tail 2371 */ 2372 atomic_clear_int(&lp->lwp_thread->td_mpflags, 2373 TDF_MP_BATCH_DEMARC); 2374 lp->lwp_rrcount = 0; 2375 TAILQ_INSERT_TAIL(q, lp, lwp_procq); 2376 } else { 2377 /* 2378 * Retain rrcount and place on head. Count is retained 2379 * even if the queue is empty. 2380 */ 2381 TAILQ_INSERT_HEAD(q, lp, lwp_procq); 2382 } 2383 *which |= 1 << pri; 2384 } 2385 2386 /* 2387 * For SMP systems a user scheduler helper thread is created for each 2388 * cpu and is used to allow one cpu to wakeup another for the purposes of 2389 * scheduling userland threads from setrunqueue(). 2390 * 2391 * UP systems do not need the helper since there is only one cpu. 2392 * 2393 * We can't use the idle thread for this because we might block. 2394 * Additionally, doing things this way allows us to HLT idle cpus 2395 * on MP systems. 2396 */ 2397 static void 2398 dfly_helper_thread(void *dummy) 2399 { 2400 globaldata_t gd; 2401 dfly_pcpu_t dd; 2402 dfly_pcpu_t rdd; 2403 struct lwp *nlp; 2404 cpumask_t mask; 2405 int cpuid; 2406 2407 gd = mycpu; 2408 cpuid = gd->gd_cpuid; /* doesn't change */ 2409 mask = gd->gd_cpumask; /* doesn't change */ 2410 dd = &dfly_pcpu[cpuid]; 2411 2412 /* 2413 * Initial interlock, make sure all dfly_pcpu[] structures have 2414 * been initialized before proceeding. 2415 */ 2416 lockmgr(&usched_dfly_config_lk, LK_SHARED); 2417 lockmgr(&usched_dfly_config_lk, LK_RELEASE); 2418 2419 /* 2420 * Since we only want to be woken up only when no user processes 2421 * are scheduled on a cpu, run at an ultra low priority. 2422 */ 2423 lwkt_setpri_self(TDPRI_USER_SCHEDULER); 2424 2425 for (;;) { 2426 /* 2427 * We use the LWKT deschedule-interlock trick to avoid racing 2428 * dfly_rdyprocmask. This means we cannot block through to the 2429 * manual lwkt_switch() call we make below. 2430 */ 2431 crit_enter_gd(gd); 2432 tsleep_interlock(dd->helper_thread, 0); 2433 2434 spin_lock(&dd->spin); 2435 if ((dd->flags & DFLY_PCPU_RDYMASK) == 0) { 2436 ATOMIC_CPUMASK_ORMASK(dfly_rdyprocmask, mask); 2437 dd->flags |= DFLY_PCPU_RDYMASK; 2438 } 2439 clear_user_resched(); /* This satisfied the reschedule request */ 2440 #if 0 2441 dd->rrcount = 0; /* Reset the round-robin counter */ 2442 #endif 2443 2444 if (dd->runqcount || dd->uschedcp != NULL) { 2445 /* 2446 * Threads are available. A thread may or may not be 2447 * currently scheduled. Get the best thread already queued 2448 * to this cpu. 2449 */ 2450 nlp = dfly_chooseproc_locked(dd, dd, dd->uschedcp, 0); 2451 if (nlp) { 2452 if ((dd->flags & DFLY_PCPU_CURMASK) == 0) { 2453 ATOMIC_CPUMASK_ORMASK(dfly_curprocmask, mask); 2454 dd->flags |= DFLY_PCPU_CURMASK; 2455 } 2456 dd->upri = nlp->lwp_priority; 2457 dd->uschedcp = nlp; 2458 #if 0 2459 dd->rrcount = 0; /* reset round robin */ 2460 #endif 2461 spin_unlock(&dd->spin); 2462 lwkt_acquire(nlp->lwp_thread); 2463 lwkt_schedule(nlp->lwp_thread); 2464 } else { 2465 /* 2466 * This situation should not occur because we had 2467 * at least one thread available. 2468 */ 2469 spin_unlock(&dd->spin); 2470 } 2471 } else if (usched_dfly_features & 0x01) { 2472 /* 2473 * This cpu is devoid of runnable threads, steal a thread 2474 * from another cpu. Since we're stealing, might as well 2475 * load balance at the same time. 2476 * 2477 * We choose the highest-loaded thread from the worst queue. 2478 * 2479 * NOTE! This function only returns a non-NULL rdd when 2480 * another cpu's queue is obviously overloaded. We 2481 * do not want to perform the type of rebalancing 2482 * the schedclock does here because it would result 2483 * in insane process pulling when 'steady' state is 2484 * partially unbalanced (e.g. 6 runnables and only 2485 * 4 cores). 2486 */ 2487 rdd = dfly_choose_worst_queue(dd, 0); 2488 if (rdd && dd->uload + usched_dfly_weight6 < rdd->uload && 2489 spin_trylock(&rdd->spin)) { 2490 nlp = dfly_chooseproc_locked(rdd, dd, NULL, 1); 2491 spin_unlock(&rdd->spin); 2492 } else { 2493 nlp = NULL; 2494 } 2495 if (nlp) { 2496 if ((dd->flags & DFLY_PCPU_CURMASK) == 0) { 2497 ATOMIC_CPUMASK_ORMASK(dfly_curprocmask, mask); 2498 dd->flags |= DFLY_PCPU_CURMASK; 2499 } 2500 dd->upri = nlp->lwp_priority; 2501 dd->uschedcp = nlp; 2502 #if 0 2503 dd->rrcount = 0; /* reset round robin */ 2504 #endif 2505 spin_unlock(&dd->spin); 2506 lwkt_acquire(nlp->lwp_thread); 2507 lwkt_schedule(nlp->lwp_thread); 2508 } else { 2509 /* 2510 * Leave the thread on our run queue. Another 2511 * scheduler will try to pull it later. 2512 */ 2513 spin_unlock(&dd->spin); 2514 } 2515 } else { 2516 /* 2517 * devoid of runnable threads and not allowed to steal 2518 * any. 2519 */ 2520 spin_unlock(&dd->spin); 2521 } 2522 2523 /* 2524 * We're descheduled unless someone scheduled us. Switch away. 2525 * Exiting the critical section will cause splz() to be called 2526 * for us if interrupts and such are pending. 2527 */ 2528 crit_exit_gd(gd); 2529 tsleep(dd->helper_thread, PINTERLOCKED, "schslp", 0); 2530 } 2531 } 2532 2533 #if 0 2534 static int 2535 sysctl_usched_dfly_stick_to_level(SYSCTL_HANDLER_ARGS) 2536 { 2537 int error, new_val; 2538 2539 new_val = usched_dfly_stick_to_level; 2540 2541 error = sysctl_handle_int(oidp, &new_val, 0, req); 2542 if (error != 0 || req->newptr == NULL) 2543 return (error); 2544 if (new_val > cpu_topology_levels_number - 1 || new_val < 0) 2545 return (EINVAL); 2546 usched_dfly_stick_to_level = new_val; 2547 return (0); 2548 } 2549 #endif 2550 2551 /* 2552 * Setup the queues and scheduler helpers (scheduler helpers are SMP only). 2553 * Note that curprocmask bit 0 has already been cleared by rqinit() and 2554 * we should not mess with it further. 2555 */ 2556 static void 2557 usched_dfly_cpu_init(void) 2558 { 2559 int i; 2560 int j; 2561 int smt_not_supported = 0; 2562 int cache_coherent_not_supported = 0; 2563 2564 if (bootverbose) 2565 kprintf("Start usched_dfly helpers on cpus:\n"); 2566 2567 sysctl_ctx_init(&usched_dfly_sysctl_ctx); 2568 usched_dfly_sysctl_tree = 2569 SYSCTL_ADD_NODE(&usched_dfly_sysctl_ctx, 2570 SYSCTL_STATIC_CHILDREN(_kern), OID_AUTO, 2571 "usched_dfly", CTLFLAG_RD, 0, ""); 2572 2573 usched_dfly_node_mem = get_highest_node_memory(); 2574 2575 lockmgr(&usched_dfly_config_lk, LK_EXCLUSIVE); 2576 2577 for (i = 0; i < ncpus; ++i) { 2578 dfly_pcpu_t dd = &dfly_pcpu[i]; 2579 cpumask_t mask; 2580 2581 CPUMASK_ASSBIT(mask, i); 2582 if (CPUMASK_TESTMASK(mask, smp_active_mask) == 0) 2583 continue; 2584 2585 spin_init(&dd->spin, "uschedcpuinit"); 2586 dd->cpunode = get_cpu_node_by_cpuid(i); 2587 dd->cpuid = i; 2588 dd->gd = globaldata_find(i); 2589 CPUMASK_ASSBIT(dd->cpumask, i); 2590 for (j = 0; j < NQS; j++) { 2591 TAILQ_INIT(&dd->queues[j]); 2592 TAILQ_INIT(&dd->rtqueues[j]); 2593 TAILQ_INIT(&dd->idqueues[j]); 2594 } 2595 ATOMIC_CPUMASK_NANDBIT(dfly_curprocmask, 0); 2596 if (i == 0) 2597 dd->flags &= ~DFLY_PCPU_CURMASK; 2598 2599 if (dd->cpunode == NULL) { 2600 smt_not_supported = 1; 2601 cache_coherent_not_supported = 1; 2602 if (bootverbose) 2603 kprintf (" cpu%d - WARNING: No CPU NODE " 2604 "found for cpu\n", i); 2605 } else { 2606 switch (dd->cpunode->type) { 2607 case THREAD_LEVEL: 2608 if (bootverbose) 2609 kprintf (" cpu%d - HyperThreading " 2610 "available. Core siblings: ", 2611 i); 2612 break; 2613 case CORE_LEVEL: 2614 smt_not_supported = 1; 2615 2616 if (bootverbose) 2617 kprintf (" cpu%d - No HT available, " 2618 "multi-core/physical " 2619 "cpu. Physical siblings: ", 2620 i); 2621 break; 2622 case CHIP_LEVEL: 2623 smt_not_supported = 1; 2624 2625 if (bootverbose) 2626 kprintf (" cpu%d - No HT available, " 2627 "single-core/physical cpu. " 2628 "Package siblings: ", 2629 i); 2630 break; 2631 default: 2632 /* Let's go for safe defaults here */ 2633 smt_not_supported = 1; 2634 cache_coherent_not_supported = 1; 2635 if (bootverbose) 2636 kprintf (" cpu%d - Unknown cpunode->" 2637 "type=%u. siblings: ", 2638 i, 2639 (u_int)dd->cpunode->type); 2640 break; 2641 } 2642 2643 if (bootverbose) { 2644 if (dd->cpunode->parent_node != NULL) { 2645 kprint_cpuset(&dd->cpunode-> 2646 parent_node->members); 2647 kprintf("\n"); 2648 } else { 2649 kprintf(" no siblings\n"); 2650 } 2651 } 2652 } 2653 2654 lwkt_create(dfly_helper_thread, NULL, &dd->helper_thread, NULL, 2655 0, i, "usched %d", i); 2656 2657 /* 2658 * Allow user scheduling on the target cpu. cpu #0 has already 2659 * been enabled in rqinit(). 2660 */ 2661 if (i) { 2662 ATOMIC_CPUMASK_NANDMASK(dfly_curprocmask, mask); 2663 dd->flags &= ~DFLY_PCPU_CURMASK; 2664 } 2665 if ((dd->flags & DFLY_PCPU_RDYMASK) == 0) { 2666 ATOMIC_CPUMASK_ORMASK(dfly_rdyprocmask, mask); 2667 dd->flags |= DFLY_PCPU_RDYMASK; 2668 } 2669 dd->upri = PRIBASE_NULL; 2670 2671 } 2672 2673 /* usched_dfly sysctl configurable parameters */ 2674 2675 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2676 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2677 OID_AUTO, "rrinterval", CTLFLAG_RW, 2678 &usched_dfly_rrinterval, 0, ""); 2679 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2680 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2681 OID_AUTO, "decay", CTLFLAG_RW, 2682 &usched_dfly_decay, 0, "Extra decay when not running"); 2683 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2684 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2685 OID_AUTO, "ipc_smt", CTLFLAG_RW, 2686 &usched_dfly_ipc_smt, 0, "Pair IPC on hyper-threads"); 2687 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2688 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2689 OID_AUTO, "ipc_same", CTLFLAG_RW, 2690 &usched_dfly_ipc_same, 0, "Pair IPC on same thread"); 2691 2692 /* Add enable/disable option for SMT scheduling if supported */ 2693 if (smt_not_supported) { 2694 usched_dfly_smt = 0; 2695 SYSCTL_ADD_STRING(&usched_dfly_sysctl_ctx, 2696 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2697 OID_AUTO, "smt", CTLFLAG_RD, 2698 "NOT SUPPORTED", 0, "SMT NOT SUPPORTED"); 2699 } else { 2700 usched_dfly_smt = 1; 2701 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2702 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2703 OID_AUTO, "smt", CTLFLAG_RW, 2704 &usched_dfly_smt, 0, "Enable SMT scheduling"); 2705 } 2706 2707 /* 2708 * Add enable/disable option for cache coherent scheduling 2709 * if supported 2710 */ 2711 if (cache_coherent_not_supported) { 2712 usched_dfly_cache_coherent = 0; 2713 SYSCTL_ADD_STRING(&usched_dfly_sysctl_ctx, 2714 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2715 OID_AUTO, "cache_coherent", CTLFLAG_RD, 2716 "NOT SUPPORTED", 0, 2717 "Cache coherence NOT SUPPORTED"); 2718 } else { 2719 usched_dfly_cache_coherent = 1; 2720 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2721 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2722 OID_AUTO, "cache_coherent", CTLFLAG_RW, 2723 &usched_dfly_cache_coherent, 0, 2724 "Enable/Disable cache coherent scheduling"); 2725 2726 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2727 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2728 OID_AUTO, "weight1", CTLFLAG_RW, 2729 &usched_dfly_weight1, 200, 2730 "Weight selection for current cpu"); 2731 2732 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2733 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2734 OID_AUTO, "weight2", CTLFLAG_RW, 2735 &usched_dfly_weight2, 180, 2736 "Weight selection for wakefrom cpu"); 2737 2738 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2739 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2740 OID_AUTO, "weight3", CTLFLAG_RW, 2741 &usched_dfly_weight3, 40, 2742 "Weight selection for num threads on queue"); 2743 2744 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2745 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2746 OID_AUTO, "weight4", CTLFLAG_RW, 2747 &usched_dfly_weight4, 160, 2748 "Availability of other idle cpus"); 2749 2750 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2751 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2752 OID_AUTO, "weight5", CTLFLAG_RW, 2753 &usched_dfly_weight5, 50, 2754 "Memory attached to node"); 2755 2756 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2757 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2758 OID_AUTO, "weight6", CTLFLAG_RW, 2759 &usched_dfly_weight6, 150, 2760 "Transfer weight"); 2761 2762 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2763 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2764 OID_AUTO, "fast_resched", CTLFLAG_RW, 2765 &usched_dfly_fast_resched, 0, 2766 "Availability of other idle cpus"); 2767 2768 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2769 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2770 OID_AUTO, "features", CTLFLAG_RW, 2771 &usched_dfly_features, 0x8F, 2772 "Allow pulls into empty queues"); 2773 2774 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2775 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2776 OID_AUTO, "swmask", CTLFLAG_RW, 2777 &usched_dfly_swmask, ~PPQMASK, 2778 "Queue mask to force thread switch"); 2779 2780 #if 0 2781 SYSCTL_ADD_PROC(&usched_dfly_sysctl_ctx, 2782 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2783 OID_AUTO, "stick_to_level", 2784 CTLTYPE_INT | CTLFLAG_RW, 2785 NULL, sizeof usched_dfly_stick_to_level, 2786 sysctl_usched_dfly_stick_to_level, "I", 2787 "Stick a process to this level. See sysctl" 2788 "paremter hw.cpu_topology.level_description"); 2789 #endif 2790 } 2791 lockmgr(&usched_dfly_config_lk, LK_RELEASE); 2792 } 2793 2794 SYSINIT(uschedtd, SI_BOOT2_USCHED, SI_ORDER_SECOND, 2795 usched_dfly_cpu_init, NULL); 2796