1 /* 2 * Copyright (c) 2012 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 #include <sys/mplock2.h> 52 53 #include <sys/ktr.h> 54 55 #include <machine/cpu.h> 56 #include <machine/smp.h> 57 58 /* 59 * Priorities. Note that with 32 run queues per scheduler each queue 60 * represents four priority levels. 61 */ 62 63 int dfly_rebalanced; 64 65 #define MAXPRI 128 66 #define PRIMASK (MAXPRI - 1) 67 #define PRIBASE_REALTIME 0 68 #define PRIBASE_NORMAL MAXPRI 69 #define PRIBASE_IDLE (MAXPRI * 2) 70 #define PRIBASE_THREAD (MAXPRI * 3) 71 #define PRIBASE_NULL (MAXPRI * 4) 72 73 #define NQS 32 /* 32 run queues. */ 74 #define PPQ (MAXPRI / NQS) /* priorities per queue */ 75 #define PPQMASK (PPQ - 1) 76 77 /* 78 * NICEPPQ - number of nice units per priority queue 79 * ESTCPUPPQ - number of estcpu units per priority queue 80 * ESTCPUMAX - number of estcpu units 81 */ 82 #define NICEPPQ 2 83 #define ESTCPUPPQ 512 84 #define ESTCPUMAX (ESTCPUPPQ * NQS) 85 #define BATCHMAX (ESTCPUFREQ * 30) 86 #define PRIO_RANGE (PRIO_MAX - PRIO_MIN + 1) 87 88 #define ESTCPULIM(v) min((v), ESTCPUMAX) 89 90 TAILQ_HEAD(rq, lwp); 91 92 #define lwp_priority lwp_usdata.dfly.priority 93 #define lwp_forked lwp_usdata.dfly.forked 94 #define lwp_rqindex lwp_usdata.dfly.rqindex 95 #define lwp_estcpu lwp_usdata.dfly.estcpu 96 #define lwp_estfast lwp_usdata.dfly.estfast 97 #define lwp_uload lwp_usdata.dfly.uload 98 #define lwp_rqtype lwp_usdata.dfly.rqtype 99 #define lwp_qcpu lwp_usdata.dfly.qcpu 100 #define lwp_rrcount lwp_usdata.dfly.rrcount 101 102 struct usched_dfly_pcpu { 103 struct spinlock spin; 104 struct thread helper_thread; 105 short unusde01; 106 short upri; 107 int uload; 108 int ucount; 109 struct lwp *uschedcp; 110 struct rq queues[NQS]; 111 struct rq rtqueues[NQS]; 112 struct rq idqueues[NQS]; 113 u_int32_t queuebits; 114 u_int32_t rtqueuebits; 115 u_int32_t idqueuebits; 116 int runqcount; 117 int cpuid; 118 cpumask_t cpumask; 119 cpu_node_t *cpunode; 120 }; 121 122 typedef struct usched_dfly_pcpu *dfly_pcpu_t; 123 124 static void dfly_acquire_curproc(struct lwp *lp); 125 static void dfly_release_curproc(struct lwp *lp); 126 static void dfly_select_curproc(globaldata_t gd); 127 static void dfly_setrunqueue(struct lwp *lp); 128 static void dfly_setrunqueue_dd(dfly_pcpu_t rdd, struct lwp *lp); 129 static void dfly_schedulerclock(struct lwp *lp, sysclock_t period, 130 sysclock_t cpstamp); 131 static void dfly_recalculate_estcpu(struct lwp *lp); 132 static void dfly_resetpriority(struct lwp *lp); 133 static void dfly_forking(struct lwp *plp, struct lwp *lp); 134 static void dfly_exiting(struct lwp *lp, struct proc *); 135 static void dfly_uload_update(struct lwp *lp); 136 static void dfly_yield(struct lwp *lp); 137 static void dfly_changeqcpu_locked(struct lwp *lp, 138 dfly_pcpu_t dd, dfly_pcpu_t rdd); 139 static dfly_pcpu_t dfly_choose_best_queue(struct lwp *lp); 140 static dfly_pcpu_t dfly_choose_worst_queue(dfly_pcpu_t dd); 141 static dfly_pcpu_t dfly_choose_queue_simple(dfly_pcpu_t dd, struct lwp *lp); 142 static void dfly_need_user_resched_remote(void *dummy); 143 static struct lwp *dfly_chooseproc_locked(dfly_pcpu_t rdd, dfly_pcpu_t dd, 144 struct lwp *chklp, int worst); 145 static void dfly_remrunqueue_locked(dfly_pcpu_t dd, struct lwp *lp); 146 static void dfly_setrunqueue_locked(dfly_pcpu_t dd, struct lwp *lp); 147 static void dfly_changedcpu(struct lwp *lp); 148 149 struct usched usched_dfly = { 150 { NULL }, 151 "dfly", "Original DragonFly Scheduler", 152 NULL, /* default registration */ 153 NULL, /* default deregistration */ 154 dfly_acquire_curproc, 155 dfly_release_curproc, 156 dfly_setrunqueue, 157 dfly_schedulerclock, 158 dfly_recalculate_estcpu, 159 dfly_resetpriority, 160 dfly_forking, 161 dfly_exiting, 162 dfly_uload_update, 163 NULL, /* setcpumask not supported */ 164 dfly_yield, 165 dfly_changedcpu 166 }; 167 168 /* 169 * We have NQS (32) run queues per scheduling class. For the normal 170 * class, there are 128 priorities scaled onto these 32 queues. New 171 * processes are added to the last entry in each queue, and processes 172 * are selected for running by taking them from the head and maintaining 173 * a simple FIFO arrangement. Realtime and Idle priority processes have 174 * and explicit 0-31 priority which maps directly onto their class queue 175 * index. When a queue has something in it, the corresponding bit is 176 * set in the queuebits variable, allowing a single read to determine 177 * the state of all 32 queues and then a ffs() to find the first busy 178 * queue. 179 */ 180 static cpumask_t dfly_curprocmask = -1; /* currently running a user process */ 181 static cpumask_t dfly_rdyprocmask; /* ready to accept a user process */ 182 static volatile int dfly_scancpu; 183 static volatile int dfly_ucount; /* total running on whole system */ 184 static struct usched_dfly_pcpu dfly_pcpu[MAXCPU]; 185 static struct sysctl_ctx_list usched_dfly_sysctl_ctx; 186 static struct sysctl_oid *usched_dfly_sysctl_tree; 187 188 /* Debug info exposed through debug.* sysctl */ 189 190 static int usched_dfly_debug = -1; 191 SYSCTL_INT(_debug, OID_AUTO, dfly_scdebug, CTLFLAG_RW, 192 &usched_dfly_debug, 0, 193 "Print debug information for this pid"); 194 195 static int usched_dfly_pid_debug = -1; 196 SYSCTL_INT(_debug, OID_AUTO, dfly_pid_debug, CTLFLAG_RW, 197 &usched_dfly_pid_debug, 0, 198 "Print KTR debug information for this pid"); 199 200 static int usched_dfly_chooser = 0; 201 SYSCTL_INT(_debug, OID_AUTO, dfly_chooser, CTLFLAG_RW, 202 &usched_dfly_chooser, 0, 203 "Print KTR debug information for this pid"); 204 205 /* 206 * Tunning usched_dfly - configurable through kern.usched_dfly. 207 * 208 * weight1 - Tries to keep threads on their current cpu. If you 209 * make this value too large the scheduler will not be 210 * able to load-balance large loads. 211 * 212 * weight2 - If non-zero, detects thread pairs undergoing synchronous 213 * communications and tries to move them closer together. 214 * Behavior is adjusted by bit 4 of features (0x10). 215 * 216 * WARNING! Weight2 is a ridiculously sensitive parameter, 217 * a small value is recommended. 218 * 219 * weight3 - Weighting based on the number of recently runnable threads 220 * on the userland scheduling queue (ignoring their loads). 221 * A nominal value here prevents high-priority (low-load) 222 * threads from accumulating on one cpu core when other 223 * cores are available. 224 * 225 * This value should be left fairly small relative to weight1 226 * and weight4. 227 * 228 * weight4 - Weighting based on other cpu queues being available 229 * or running processes with higher lwp_priority's. 230 * 231 * This allows a thread to migrate to another nearby cpu if it 232 * is unable to run on the current cpu based on the other cpu 233 * being idle or running a lower priority (higher lwp_priority) 234 * thread. This value should be large enough to override weight1 235 * 236 * features - These flags can be set or cleared to enable or disable various 237 * features. 238 * 239 * 0x01 Enable idle-cpu pulling (default) 240 * 0x02 Enable proactive pushing (default) 241 * 0x04 Enable rebalancing rover (default) 242 * 0x08 Enable more proactive pushing (default) 243 * 0x10 (flip weight2 limit on same cpu) (default) 244 * 0x20 choose best cpu for forked process 245 * 0x40 choose current cpu for forked process 246 * 0x80 choose random cpu for forked process (default) 247 */ 248 static int usched_dfly_smt = 0; 249 static int usched_dfly_cache_coherent = 0; 250 static int usched_dfly_weight1 = 200; /* keep thread on current cpu */ 251 static int usched_dfly_weight2 = 180; /* synchronous peer's current cpu */ 252 static int usched_dfly_weight3 = 40; /* number of threads on queue */ 253 static int usched_dfly_weight4 = 160; /* availability of idle cores */ 254 static int usched_dfly_features = 0x8F; /* allow pulls */ 255 static int usched_dfly_fast_resched = 0;/* delta priority / resched */ 256 static int usched_dfly_swmask = ~PPQMASK; /* allow pulls */ 257 static int usched_dfly_rrinterval = (ESTCPUFREQ + 9) / 10; 258 static int usched_dfly_decay = 8; 259 260 /* KTR debug printings */ 261 262 KTR_INFO_MASTER(usched); 263 264 #if !defined(KTR_USCHED_DFLY) 265 #define KTR_USCHED_DFLY KTR_ALL 266 #endif 267 268 KTR_INFO(KTR_USCHED_DFLY, usched, chooseproc, 0, 269 "USCHED_DFLY(chooseproc: pid %d, old_cpuid %d, curr_cpuid %d)", 270 pid_t pid, int old_cpuid, int curr); 271 272 /* 273 * This function is called when the kernel intends to return to userland. 274 * It is responsible for making the thread the current designated userland 275 * thread for this cpu, blocking if necessary. 276 * 277 * The kernel will not depress our LWKT priority until after we return, 278 * in case we have to shove over to another cpu. 279 * 280 * We must determine our thread's disposition before we switch away. This 281 * is very sensitive code. 282 * 283 * WARNING! THIS FUNCTION IS ALLOWED TO CAUSE THE CURRENT THREAD TO MIGRATE 284 * TO ANOTHER CPU! Because most of the kernel assumes that no migration will 285 * occur, this function is called only under very controlled circumstances. 286 */ 287 static void 288 dfly_acquire_curproc(struct lwp *lp) 289 { 290 globaldata_t gd; 291 dfly_pcpu_t dd; 292 dfly_pcpu_t rdd; 293 thread_t td; 294 int force_resched; 295 296 /* 297 * Make sure we aren't sitting on a tsleep queue. 298 */ 299 td = lp->lwp_thread; 300 crit_enter_quick(td); 301 if (td->td_flags & TDF_TSLEEPQ) 302 tsleep_remove(td); 303 dfly_recalculate_estcpu(lp); 304 305 gd = mycpu; 306 dd = &dfly_pcpu[gd->gd_cpuid]; 307 308 /* 309 * Process any pending interrupts/ipi's, then handle reschedule 310 * requests. dfly_release_curproc() will try to assign a new 311 * uschedcp that isn't us and otherwise NULL it out. 312 */ 313 force_resched = 0; 314 if ((td->td_mpflags & TDF_MP_BATCH_DEMARC) && 315 lp->lwp_rrcount >= usched_dfly_rrinterval / 2) { 316 force_resched = 1; 317 } 318 319 if (user_resched_wanted()) { 320 if (dd->uschedcp == lp) 321 force_resched = 1; 322 clear_user_resched(); 323 dfly_release_curproc(lp); 324 } 325 326 /* 327 * Loop until we are the current user thread. 328 * 329 * NOTE: dd spinlock not held at top of loop. 330 */ 331 if (dd->uschedcp == lp) 332 lwkt_yield_quick(); 333 334 while (dd->uschedcp != lp) { 335 lwkt_yield_quick(); 336 337 spin_lock(&dd->spin); 338 339 if (force_resched && 340 (usched_dfly_features & 0x08) && 341 (rdd = dfly_choose_best_queue(lp)) != dd) { 342 /* 343 * We are not or are no longer the current lwp and a 344 * forced reschedule was requested. Figure out the 345 * best cpu to run on (our current cpu will be given 346 * significant weight). 347 * 348 * (if a reschedule was not requested we want to 349 * move this step after the uschedcp tests). 350 */ 351 dfly_changeqcpu_locked(lp, dd, rdd); 352 spin_unlock(&dd->spin); 353 lwkt_deschedule(lp->lwp_thread); 354 dfly_setrunqueue_dd(rdd, lp); 355 lwkt_switch(); 356 gd = mycpu; 357 dd = &dfly_pcpu[gd->gd_cpuid]; 358 continue; 359 } 360 361 /* 362 * Either no reschedule was requested or the best queue was 363 * dd, and no current process has been selected. We can 364 * trivially become the current lwp on the current cpu. 365 */ 366 if (dd->uschedcp == NULL) { 367 atomic_clear_int(&lp->lwp_thread->td_mpflags, 368 TDF_MP_DIDYIELD); 369 atomic_set_cpumask(&dfly_curprocmask, gd->gd_cpumask); 370 dd->uschedcp = lp; 371 dd->upri = lp->lwp_priority; 372 KKASSERT(lp->lwp_qcpu == dd->cpuid); 373 spin_unlock(&dd->spin); 374 break; 375 } 376 377 /* 378 * Put us back on the same run queue unconditionally. 379 * 380 * Set rrinterval to force placement at end of queue. 381 * Select the worst queue to ensure we round-robin, 382 * but do not change estcpu. 383 */ 384 if (lp->lwp_thread->td_mpflags & TDF_MP_DIDYIELD) { 385 u_int32_t tsqbits; 386 387 switch(lp->lwp_rqtype) { 388 case RTP_PRIO_NORMAL: 389 tsqbits = dd->queuebits; 390 spin_unlock(&dd->spin); 391 392 lp->lwp_rrcount = usched_dfly_rrinterval; 393 if (tsqbits) 394 lp->lwp_rqindex = bsrl(tsqbits); 395 break; 396 default: 397 spin_unlock(&dd->spin); 398 break; 399 } 400 lwkt_deschedule(lp->lwp_thread); 401 dfly_setrunqueue_dd(dd, lp); 402 atomic_clear_int(&lp->lwp_thread->td_mpflags, 403 TDF_MP_DIDYIELD); 404 lwkt_switch(); 405 gd = mycpu; 406 dd = &dfly_pcpu[gd->gd_cpuid]; 407 continue; 408 } 409 410 /* 411 * Can we steal the current designated user thread? 412 * 413 * If we do the other thread will stall when it tries to 414 * return to userland, possibly rescheduling elsewhere. 415 * 416 * It is important to do a masked test to avoid the edge 417 * case where two near-equal-priority threads are constantly 418 * interrupting each other. 419 * 420 * In the exact match case another thread has already gained 421 * uschedcp and lowered its priority, if we steal it the 422 * other thread will stay stuck on the LWKT runq and not 423 * push to another cpu. So don't steal on equal-priority even 424 * though it might appear to be more beneficial due to not 425 * having to switch back to the other thread's context. 426 * 427 * usched_dfly_fast_resched requires that two threads be 428 * significantly far apart in priority in order to interrupt. 429 * 430 * If better but not sufficiently far apart, the current 431 * uschedcp will be interrupted at the next scheduler clock. 432 */ 433 if (dd->uschedcp && 434 (dd->upri & ~PPQMASK) > 435 (lp->lwp_priority & ~PPQMASK) + usched_dfly_fast_resched) { 436 dd->uschedcp = lp; 437 dd->upri = lp->lwp_priority; 438 KKASSERT(lp->lwp_qcpu == dd->cpuid); 439 spin_unlock(&dd->spin); 440 break; 441 } 442 /* 443 * We are not the current lwp, figure out the best cpu 444 * to run on (our current cpu will be given significant 445 * weight). Loop on cpu change. 446 */ 447 if ((usched_dfly_features & 0x02) && 448 force_resched == 0 && 449 (rdd = dfly_choose_best_queue(lp)) != dd) { 450 dfly_changeqcpu_locked(lp, dd, rdd); 451 spin_unlock(&dd->spin); 452 lwkt_deschedule(lp->lwp_thread); 453 dfly_setrunqueue_dd(rdd, lp); 454 lwkt_switch(); 455 gd = mycpu; 456 dd = &dfly_pcpu[gd->gd_cpuid]; 457 continue; 458 } 459 460 /* 461 * We cannot become the current lwp, place the lp on the 462 * run-queue of this or another cpu and deschedule ourselves. 463 * 464 * When we are reactivated we will have another chance. 465 * 466 * Reload after a switch or setrunqueue/switch possibly 467 * moved us to another cpu. 468 */ 469 spin_unlock(&dd->spin); 470 lwkt_deschedule(lp->lwp_thread); 471 dfly_setrunqueue_dd(dd, lp); 472 lwkt_switch(); 473 gd = mycpu; 474 dd = &dfly_pcpu[gd->gd_cpuid]; 475 } 476 477 /* 478 * Make sure upri is synchronized, then yield to LWKT threads as 479 * needed before returning. This could result in another reschedule. 480 * XXX 481 */ 482 crit_exit_quick(td); 483 484 KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); 485 } 486 487 /* 488 * DFLY_RELEASE_CURPROC 489 * 490 * This routine detaches the current thread from the userland scheduler, 491 * usually because the thread needs to run or block in the kernel (at 492 * kernel priority) for a while. 493 * 494 * This routine is also responsible for selecting a new thread to 495 * make the current thread. 496 * 497 * NOTE: This implementation differs from the dummy example in that 498 * dfly_select_curproc() is able to select the current process, whereas 499 * dummy_select_curproc() is not able to select the current process. 500 * This means we have to NULL out uschedcp. 501 * 502 * Additionally, note that we may already be on a run queue if releasing 503 * via the lwkt_switch() in dfly_setrunqueue(). 504 */ 505 static void 506 dfly_release_curproc(struct lwp *lp) 507 { 508 globaldata_t gd = mycpu; 509 dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid]; 510 511 /* 512 * Make sure td_wakefromcpu is defaulted. This will be overwritten 513 * by wakeup(). 514 */ 515 if (dd->uschedcp == lp) { 516 KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); 517 spin_lock(&dd->spin); 518 if (dd->uschedcp == lp) { 519 dd->uschedcp = NULL; /* don't let lp be selected */ 520 dd->upri = PRIBASE_NULL; 521 atomic_clear_cpumask(&dfly_curprocmask, gd->gd_cpumask); 522 spin_unlock(&dd->spin); 523 dfly_select_curproc(gd); 524 } else { 525 spin_unlock(&dd->spin); 526 } 527 } 528 } 529 530 /* 531 * DFLY_SELECT_CURPROC 532 * 533 * Select a new current process for this cpu and clear any pending user 534 * reschedule request. The cpu currently has no current process. 535 * 536 * This routine is also responsible for equal-priority round-robining, 537 * typically triggered from dfly_schedulerclock(). In our dummy example 538 * all the 'user' threads are LWKT scheduled all at once and we just 539 * call lwkt_switch(). 540 * 541 * The calling process is not on the queue and cannot be selected. 542 */ 543 static 544 void 545 dfly_select_curproc(globaldata_t gd) 546 { 547 dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid]; 548 struct lwp *nlp; 549 int cpuid = gd->gd_cpuid; 550 551 crit_enter_gd(gd); 552 553 spin_lock(&dd->spin); 554 nlp = dfly_chooseproc_locked(dd, dd, dd->uschedcp, 0); 555 556 if (nlp) { 557 atomic_set_cpumask(&dfly_curprocmask, CPUMASK(cpuid)); 558 dd->upri = nlp->lwp_priority; 559 dd->uschedcp = nlp; 560 #if 0 561 dd->rrcount = 0; /* reset round robin */ 562 #endif 563 spin_unlock(&dd->spin); 564 lwkt_acquire(nlp->lwp_thread); 565 lwkt_schedule(nlp->lwp_thread); 566 } else { 567 spin_unlock(&dd->spin); 568 } 569 crit_exit_gd(gd); 570 } 571 572 /* 573 * Place the specified lwp on the user scheduler's run queue. This routine 574 * must be called with the thread descheduled. The lwp must be runnable. 575 * It must not be possible for anyone else to explicitly schedule this thread. 576 * 577 * The thread may be the current thread as a special case. 578 */ 579 static void 580 dfly_setrunqueue(struct lwp *lp) 581 { 582 dfly_pcpu_t dd; 583 dfly_pcpu_t rdd; 584 585 /* 586 * First validate the process LWKT state. 587 */ 588 KASSERT(lp->lwp_stat == LSRUN, ("setrunqueue: lwp not LSRUN")); 589 KASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0, 590 ("lwp %d/%d already on runq! flag %08x/%08x", lp->lwp_proc->p_pid, 591 lp->lwp_tid, lp->lwp_proc->p_flags, lp->lwp_flags)); 592 KKASSERT((lp->lwp_thread->td_flags & TDF_RUNQ) == 0); 593 594 /* 595 * NOTE: dd/rdd do not necessarily represent the current cpu. 596 * Instead they may represent the cpu the thread was last 597 * scheduled on or inherited by its parent. 598 */ 599 dd = &dfly_pcpu[lp->lwp_qcpu]; 600 rdd = dd; 601 602 /* 603 * This process is not supposed to be scheduled anywhere or assigned 604 * as the current process anywhere. Assert the condition. 605 */ 606 KKASSERT(rdd->uschedcp != lp); 607 608 /* 609 * Ok, we have to setrunqueue some target cpu and request a reschedule 610 * if necessary. 611 * 612 * We have to choose the best target cpu. It might not be the current 613 * target even if the current cpu has no running user thread (for 614 * example, because the current cpu might be a hyperthread and its 615 * sibling has a thread assigned). 616 * 617 * If we just forked it is most optimal to run the child on the same 618 * cpu just in case the parent decides to wait for it (thus getting 619 * off that cpu). As long as there is nothing else runnable on the 620 * cpu, that is. If we did this unconditionally a parent forking 621 * multiple children before waiting (e.g. make -j N) leaves other 622 * cpus idle that could be working. 623 */ 624 if (lp->lwp_forked) { 625 lp->lwp_forked = 0; 626 if (usched_dfly_features & 0x20) 627 rdd = dfly_choose_best_queue(lp); 628 else if (usched_dfly_features & 0x40) 629 rdd = &dfly_pcpu[lp->lwp_qcpu]; 630 else if (usched_dfly_features & 0x80) 631 rdd = dfly_choose_queue_simple(rdd, lp); 632 else if (dfly_pcpu[lp->lwp_qcpu].runqcount) 633 rdd = dfly_choose_best_queue(lp); 634 else 635 rdd = &dfly_pcpu[lp->lwp_qcpu]; 636 } else { 637 rdd = dfly_choose_best_queue(lp); 638 /* rdd = &dfly_pcpu[lp->lwp_qcpu]; */ 639 } 640 if (lp->lwp_qcpu != rdd->cpuid) { 641 spin_lock(&dd->spin); 642 dfly_changeqcpu_locked(lp, dd, rdd); 643 spin_unlock(&dd->spin); 644 } 645 dfly_setrunqueue_dd(rdd, lp); 646 } 647 648 /* 649 * Change qcpu to rdd->cpuid. The dd the lp is CURRENTLY on must be 650 * spin-locked on-call. rdd does not have to be. 651 */ 652 static void 653 dfly_changeqcpu_locked(struct lwp *lp, dfly_pcpu_t dd, dfly_pcpu_t rdd) 654 { 655 if (lp->lwp_qcpu != rdd->cpuid) { 656 if (lp->lwp_mpflags & LWP_MP_ULOAD) { 657 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ULOAD); 658 atomic_add_int(&dd->uload, -lp->lwp_uload); 659 atomic_add_int(&dd->ucount, -1); 660 atomic_add_int(&dfly_ucount, -1); 661 } 662 lp->lwp_qcpu = rdd->cpuid; 663 } 664 } 665 666 /* 667 * Place lp on rdd's runqueue. Nothing is locked on call. This function 668 * also performs all necessary ancillary notification actions. 669 */ 670 static void 671 dfly_setrunqueue_dd(dfly_pcpu_t rdd, struct lwp *lp) 672 { 673 globaldata_t rgd; 674 675 /* 676 * We might be moving the lp to another cpu's run queue, and once 677 * on the runqueue (even if it is our cpu's), another cpu can rip 678 * it away from us. 679 * 680 * TDF_MIGRATING might already be set if this is part of a 681 * remrunqueue+setrunqueue sequence. 682 */ 683 if ((lp->lwp_thread->td_flags & TDF_MIGRATING) == 0) 684 lwkt_giveaway(lp->lwp_thread); 685 686 rgd = globaldata_find(rdd->cpuid); 687 688 /* 689 * We lose control of the lp the moment we release the spinlock 690 * after having placed it on the queue. i.e. another cpu could pick 691 * it up, or it could exit, or its priority could be further 692 * adjusted, or something like that. 693 * 694 * WARNING! rdd can point to a foreign cpu! 695 */ 696 spin_lock(&rdd->spin); 697 dfly_setrunqueue_locked(rdd, lp); 698 699 /* 700 * Potentially interrupt the currently-running thread 701 */ 702 if ((rdd->upri & ~PPQMASK) <= (lp->lwp_priority & ~PPQMASK)) { 703 /* 704 * Currently running thread is better or same, do not 705 * interrupt. 706 */ 707 spin_unlock(&rdd->spin); 708 } else if ((rdd->upri & ~PPQMASK) <= (lp->lwp_priority & ~PPQMASK) + 709 usched_dfly_fast_resched) { 710 /* 711 * Currently running thread is not better, but not so bad 712 * that we need to interrupt it. Let it run for one more 713 * scheduler tick. 714 */ 715 if (rdd->uschedcp && 716 rdd->uschedcp->lwp_rrcount < usched_dfly_rrinterval) { 717 rdd->uschedcp->lwp_rrcount = usched_dfly_rrinterval - 1; 718 } 719 spin_unlock(&rdd->spin); 720 } else if (rgd == mycpu) { 721 /* 722 * We should interrupt the currently running thread, which 723 * is on the current cpu. However, if DIDYIELD is set we 724 * round-robin unconditionally and do not interrupt it. 725 */ 726 spin_unlock(&rdd->spin); 727 if (rdd->uschedcp == NULL) 728 wakeup_mycpu(&rdd->helper_thread); /* XXX */ 729 if ((lp->lwp_thread->td_mpflags & TDF_MP_DIDYIELD) == 0) 730 need_user_resched(); 731 } else { 732 /* 733 * We should interrupt the currently running thread, which 734 * is on a different cpu. 735 */ 736 spin_unlock(&rdd->spin); 737 lwkt_send_ipiq(rgd, dfly_need_user_resched_remote, NULL); 738 } 739 } 740 741 /* 742 * This routine is called from a systimer IPI. It MUST be MP-safe and 743 * the BGL IS NOT HELD ON ENTRY. This routine is called at ESTCPUFREQ on 744 * each cpu. 745 */ 746 static 747 void 748 dfly_schedulerclock(struct lwp *lp, sysclock_t period, sysclock_t cpstamp) 749 { 750 globaldata_t gd = mycpu; 751 dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid]; 752 753 /* 754 * Spinlocks also hold a critical section so there should not be 755 * any active. 756 */ 757 KKASSERT(gd->gd_spinlocks == 0); 758 759 if (lp == NULL) 760 return; 761 762 /* 763 * Do we need to round-robin? We round-robin 10 times a second. 764 * This should only occur for cpu-bound batch processes. 765 */ 766 if (++lp->lwp_rrcount >= usched_dfly_rrinterval) { 767 lp->lwp_thread->td_wakefromcpu = -1; 768 need_user_resched(); 769 } 770 771 /* 772 * Adjust estcpu upward using a real time equivalent calculation, 773 * and recalculate lp's priority. 774 */ 775 lp->lwp_estcpu = ESTCPULIM(lp->lwp_estcpu + ESTCPUMAX / ESTCPUFREQ + 1); 776 dfly_resetpriority(lp); 777 778 /* 779 * Rebalance two cpus every 8 ticks, pulling the worst thread 780 * from the worst cpu's queue into a rotating cpu number. 781 * 782 * This mechanic is needed because the push algorithms can 783 * steady-state in an non-optimal configuration. We need to mix it 784 * up a little, even if it means breaking up a paired thread, so 785 * the push algorithms can rebalance the degenerate conditions. 786 * This portion of the algorithm exists to ensure stability at the 787 * selected weightings. 788 * 789 * Because we might be breaking up optimal conditions we do not want 790 * to execute this too quickly, hence we only rebalance approximately 791 * ~7-8 times per second. The push's, on the otherhand, are capable 792 * moving threads to other cpus at a much higher rate. 793 * 794 * We choose the most heavily loaded thread from the worst queue 795 * in order to ensure that multiple heavy-weight threads on the same 796 * queue get broken up, and also because these threads are the most 797 * likely to be able to remain in place. Hopefully then any pairings, 798 * if applicable, migrate to where these threads are. 799 */ 800 if ((usched_dfly_features & 0x04) && 801 ((u_int)sched_ticks & 7) == 0 && 802 (u_int)sched_ticks / 8 % ncpus == gd->gd_cpuid) { 803 /* 804 * Our cpu is up. 805 */ 806 struct lwp *nlp; 807 dfly_pcpu_t rdd; 808 809 rdd = dfly_choose_worst_queue(dd); 810 if (rdd) { 811 spin_lock(&dd->spin); 812 if (spin_trylock(&rdd->spin)) { 813 nlp = dfly_chooseproc_locked(rdd, dd, NULL, 1); 814 spin_unlock(&rdd->spin); 815 if (nlp == NULL) 816 spin_unlock(&dd->spin); 817 } else { 818 spin_unlock(&dd->spin); 819 nlp = NULL; 820 } 821 } else { 822 nlp = NULL; 823 } 824 /* dd->spin held if nlp != NULL */ 825 826 /* 827 * Either schedule it or add it to our queue. 828 */ 829 if (nlp && 830 (nlp->lwp_priority & ~PPQMASK) < (dd->upri & ~PPQMASK)) { 831 atomic_set_cpumask(&dfly_curprocmask, dd->cpumask); 832 dd->upri = nlp->lwp_priority; 833 dd->uschedcp = nlp; 834 #if 0 835 dd->rrcount = 0; /* reset round robin */ 836 #endif 837 spin_unlock(&dd->spin); 838 lwkt_acquire(nlp->lwp_thread); 839 lwkt_schedule(nlp->lwp_thread); 840 } else if (nlp) { 841 dfly_setrunqueue_locked(dd, nlp); 842 spin_unlock(&dd->spin); 843 } 844 } 845 } 846 847 /* 848 * Called from acquire and from kern_synch's one-second timer (one of the 849 * callout helper threads) with a critical section held. 850 * 851 * Adjust p_estcpu based on our single-cpu load, p_nice, and compensate for 852 * overall system load. 853 * 854 * Note that no recalculation occurs for a process which sleeps and wakes 855 * up in the same tick. That is, a system doing thousands of context 856 * switches per second will still only do serious estcpu calculations 857 * ESTCPUFREQ times per second. 858 */ 859 static 860 void 861 dfly_recalculate_estcpu(struct lwp *lp) 862 { 863 globaldata_t gd = mycpu; 864 sysclock_t cpbase; 865 sysclock_t ttlticks; 866 int estcpu; 867 int decay_factor; 868 int ucount; 869 870 /* 871 * We have to subtract periodic to get the last schedclock 872 * timeout time, otherwise we would get the upcoming timeout. 873 * Keep in mind that a process can migrate between cpus and 874 * while the scheduler clock should be very close, boundary 875 * conditions could lead to a small negative delta. 876 */ 877 cpbase = gd->gd_schedclock.time - gd->gd_schedclock.periodic; 878 879 if (lp->lwp_slptime > 1) { 880 /* 881 * Too much time has passed, do a coarse correction. 882 */ 883 lp->lwp_estcpu = lp->lwp_estcpu >> 1; 884 dfly_resetpriority(lp); 885 lp->lwp_cpbase = cpbase; 886 lp->lwp_cpticks = 0; 887 lp->lwp_estfast = 0; 888 } else if (lp->lwp_cpbase != cpbase) { 889 /* 890 * Adjust estcpu if we are in a different tick. Don't waste 891 * time if we are in the same tick. 892 * 893 * First calculate the number of ticks in the measurement 894 * interval. The ttlticks calculation can wind up 0 due to 895 * a bug in the handling of lwp_slptime (as yet not found), 896 * so make sure we do not get a divide by 0 panic. 897 */ 898 ttlticks = (cpbase - lp->lwp_cpbase) / 899 gd->gd_schedclock.periodic; 900 if ((ssysclock_t)ttlticks < 0) { 901 ttlticks = 0; 902 lp->lwp_cpbase = cpbase; 903 } 904 if (ttlticks == 0) 905 return; 906 updatepcpu(lp, lp->lwp_cpticks, ttlticks); 907 908 /* 909 * Calculate the percentage of one cpu being used then 910 * compensate for any system load in excess of ncpus. 911 * 912 * For example, if we have 8 cores and 16 running cpu-bound 913 * processes then all things being equal each process will 914 * get 50% of one cpu. We need to pump this value back 915 * up to 100% so the estcpu calculation properly adjusts 916 * the process's dynamic priority. 917 * 918 * estcpu is scaled by ESTCPUMAX, pctcpu is scaled by FSCALE. 919 */ 920 estcpu = (lp->lwp_pctcpu * ESTCPUMAX) >> FSHIFT; 921 ucount = dfly_ucount; 922 if (ucount > ncpus) { 923 estcpu += estcpu * (ucount - ncpus) / ncpus; 924 } 925 926 if (usched_dfly_debug == lp->lwp_proc->p_pid) { 927 kprintf("pid %d lwp %p estcpu %3d %3d cp %d/%d", 928 lp->lwp_proc->p_pid, lp, 929 estcpu, lp->lwp_estcpu, 930 lp->lwp_cpticks, ttlticks); 931 } 932 933 /* 934 * Adjust lp->lwp_esetcpu. The decay factor determines how 935 * quickly lwp_estcpu collapses to its realtime calculation. 936 * A slower collapse gives us a more accurate number over 937 * the long term but can create problems with bursty threads 938 * or threads which become cpu hogs. 939 * 940 * To solve this problem, newly started lwps and lwps which 941 * are restarting after having been asleep for a while are 942 * given a much, much faster decay in order to quickly 943 * detect whether they become cpu-bound. 944 * 945 * NOTE: p_nice is accounted for in dfly_resetpriority(), 946 * and not here, but we must still ensure that a 947 * cpu-bound nice -20 process does not completely 948 * override a cpu-bound nice +20 process. 949 * 950 * NOTE: We must use ESTCPULIM() here to deal with any 951 * overshoot. 952 */ 953 decay_factor = usched_dfly_decay; 954 if (decay_factor < 1) 955 decay_factor = 1; 956 if (decay_factor > 1024) 957 decay_factor = 1024; 958 959 if (lp->lwp_estfast < usched_dfly_decay) { 960 ++lp->lwp_estfast; 961 lp->lwp_estcpu = ESTCPULIM( 962 (lp->lwp_estcpu * lp->lwp_estfast + estcpu) / 963 (lp->lwp_estfast + 1)); 964 } else { 965 lp->lwp_estcpu = ESTCPULIM( 966 (lp->lwp_estcpu * decay_factor + estcpu) / 967 (decay_factor + 1)); 968 } 969 970 if (usched_dfly_debug == lp->lwp_proc->p_pid) 971 kprintf(" finalestcpu %d\n", lp->lwp_estcpu); 972 dfly_resetpriority(lp); 973 lp->lwp_cpbase += ttlticks * gd->gd_schedclock.periodic; 974 lp->lwp_cpticks = 0; 975 } 976 } 977 978 /* 979 * Compute the priority of a process when running in user mode. 980 * Arrange to reschedule if the resulting priority is better 981 * than that of the current process. 982 * 983 * This routine may be called with any process. 984 * 985 * This routine is called by fork1() for initial setup with the process 986 * of the run queue, and also may be called normally with the process on or 987 * off the run queue. 988 */ 989 static void 990 dfly_resetpriority(struct lwp *lp) 991 { 992 dfly_pcpu_t rdd; 993 int newpriority; 994 u_short newrqtype; 995 int rcpu; 996 int checkpri; 997 int estcpu; 998 int delta_uload; 999 1000 crit_enter(); 1001 1002 /* 1003 * Lock the scheduler (lp) belongs to. This can be on a different 1004 * cpu. Handle races. This loop breaks out with the appropriate 1005 * rdd locked. 1006 */ 1007 for (;;) { 1008 rcpu = lp->lwp_qcpu; 1009 cpu_ccfence(); 1010 rdd = &dfly_pcpu[rcpu]; 1011 spin_lock(&rdd->spin); 1012 if (rcpu == lp->lwp_qcpu) 1013 break; 1014 spin_unlock(&rdd->spin); 1015 } 1016 1017 /* 1018 * Calculate the new priority and queue type 1019 */ 1020 newrqtype = lp->lwp_rtprio.type; 1021 1022 switch(newrqtype) { 1023 case RTP_PRIO_REALTIME: 1024 case RTP_PRIO_FIFO: 1025 newpriority = PRIBASE_REALTIME + 1026 (lp->lwp_rtprio.prio & PRIMASK); 1027 break; 1028 case RTP_PRIO_NORMAL: 1029 /* 1030 * 1031 */ 1032 estcpu = lp->lwp_estcpu; 1033 1034 /* 1035 * p_nice piece Adds (0-40) * 2 0-80 1036 * estcpu Adds 16384 * 4 / 512 0-128 1037 */ 1038 newpriority = (lp->lwp_proc->p_nice - PRIO_MIN) * PPQ / NICEPPQ; 1039 newpriority += estcpu * PPQ / ESTCPUPPQ; 1040 newpriority = newpriority * MAXPRI / (PRIO_RANGE * PPQ / 1041 NICEPPQ + ESTCPUMAX * PPQ / ESTCPUPPQ); 1042 newpriority = PRIBASE_NORMAL + (newpriority & PRIMASK); 1043 break; 1044 case RTP_PRIO_IDLE: 1045 newpriority = PRIBASE_IDLE + (lp->lwp_rtprio.prio & PRIMASK); 1046 break; 1047 case RTP_PRIO_THREAD: 1048 newpriority = PRIBASE_THREAD + (lp->lwp_rtprio.prio & PRIMASK); 1049 break; 1050 default: 1051 panic("Bad RTP_PRIO %d", newrqtype); 1052 /* NOT REACHED */ 1053 } 1054 1055 /* 1056 * The LWKT scheduler doesn't dive usched structures, give it a hint 1057 * on the relative priority of user threads running in the kernel. 1058 * The LWKT scheduler will always ensure that a user thread running 1059 * in the kernel will get cpu some time, regardless of its upri, 1060 * but can decide not to instantly switch from one kernel or user 1061 * mode user thread to a kernel-mode user thread when it has a less 1062 * desireable user priority. 1063 * 1064 * td_upri has normal sense (higher values are more desireable), so 1065 * negate it. 1066 */ 1067 lp->lwp_thread->td_upri = -(newpriority & usched_dfly_swmask); 1068 1069 /* 1070 * The newpriority incorporates the queue type so do a simple masked 1071 * check to determine if the process has moved to another queue. If 1072 * it has, and it is currently on a run queue, then move it. 1073 * 1074 * Since uload is ~PPQMASK masked, no modifications are necessary if 1075 * we end up in the same run queue. 1076 */ 1077 if ((lp->lwp_priority ^ newpriority) & ~PPQMASK) { 1078 if (lp->lwp_mpflags & LWP_MP_ONRUNQ) { 1079 dfly_remrunqueue_locked(rdd, lp); 1080 lp->lwp_priority = newpriority; 1081 lp->lwp_rqtype = newrqtype; 1082 lp->lwp_rqindex = (newpriority & PRIMASK) / PPQ; 1083 dfly_setrunqueue_locked(rdd, lp); 1084 checkpri = 1; 1085 } else { 1086 lp->lwp_priority = newpriority; 1087 lp->lwp_rqtype = newrqtype; 1088 lp->lwp_rqindex = (newpriority & PRIMASK) / PPQ; 1089 checkpri = 0; 1090 } 1091 } else { 1092 /* 1093 * In the same PPQ, uload cannot change. 1094 */ 1095 lp->lwp_priority = newpriority; 1096 checkpri = 1; 1097 rcpu = -1; 1098 } 1099 1100 /* 1101 * Adjust effective load. 1102 * 1103 * Calculate load then scale up or down geometrically based on p_nice. 1104 * Processes niced up (positive) are less important, and processes 1105 * niced downard (negative) are more important. The higher the uload, 1106 * the more important the thread. 1107 */ 1108 /* 0-511, 0-100% cpu */ 1109 delta_uload = lp->lwp_estcpu / NQS; 1110 delta_uload -= delta_uload * lp->lwp_proc->p_nice / (PRIO_MAX + 1); 1111 1112 1113 delta_uload -= lp->lwp_uload; 1114 lp->lwp_uload += delta_uload; 1115 if (lp->lwp_mpflags & LWP_MP_ULOAD) 1116 atomic_add_int(&dfly_pcpu[lp->lwp_qcpu].uload, delta_uload); 1117 1118 /* 1119 * Determine if we need to reschedule the target cpu. This only 1120 * occurs if the LWP is already on a scheduler queue, which means 1121 * that idle cpu notification has already occured. At most we 1122 * need only issue a need_user_resched() on the appropriate cpu. 1123 * 1124 * The LWP may be owned by a CPU different from the current one, 1125 * in which case dd->uschedcp may be modified without an MP lock 1126 * or a spinlock held. The worst that happens is that the code 1127 * below causes a spurious need_user_resched() on the target CPU 1128 * and dd->pri to be wrong for a short period of time, both of 1129 * which are harmless. 1130 * 1131 * If checkpri is 0 we are adjusting the priority of the current 1132 * process, possibly higher (less desireable), so ignore the upri 1133 * check which will fail in that case. 1134 */ 1135 if (rcpu >= 0) { 1136 if ((dfly_rdyprocmask & CPUMASK(rcpu)) && 1137 (checkpri == 0 || 1138 (rdd->upri & ~PRIMASK) > 1139 (lp->lwp_priority & ~PRIMASK))) { 1140 if (rcpu == mycpu->gd_cpuid) { 1141 spin_unlock(&rdd->spin); 1142 need_user_resched(); 1143 } else { 1144 spin_unlock(&rdd->spin); 1145 lwkt_send_ipiq(globaldata_find(rcpu), 1146 dfly_need_user_resched_remote, 1147 NULL); 1148 } 1149 } else { 1150 spin_unlock(&rdd->spin); 1151 } 1152 } else { 1153 spin_unlock(&rdd->spin); 1154 } 1155 crit_exit(); 1156 } 1157 1158 static 1159 void 1160 dfly_yield(struct lwp *lp) 1161 { 1162 if (lp->lwp_qcpu != mycpu->gd_cpuid) 1163 return; 1164 KKASSERT(lp == curthread->td_lwp); 1165 1166 /* 1167 * Don't set need_user_resched() or mess with rrcount or anything. 1168 * the TDF flag will override everything as long as we release. 1169 */ 1170 atomic_set_int(&lp->lwp_thread->td_mpflags, TDF_MP_DIDYIELD); 1171 dfly_release_curproc(lp); 1172 } 1173 1174 /* 1175 * Thread was forcefully migrated to another cpu. Normally forced migrations 1176 * are used for iterations and the kernel returns to the original cpu before 1177 * returning and this is not needed. However, if the kernel migrates a 1178 * thread to another cpu and wants to leave it there, it has to call this 1179 * scheduler helper. 1180 * 1181 * Note that the lwkt_migratecpu() function also released the thread, so 1182 * we don't have to worry about that. 1183 */ 1184 static 1185 void 1186 dfly_changedcpu(struct lwp *lp) 1187 { 1188 dfly_pcpu_t dd = &dfly_pcpu[lp->lwp_qcpu]; 1189 dfly_pcpu_t rdd = &dfly_pcpu[mycpu->gd_cpuid]; 1190 1191 if (dd != rdd) { 1192 spin_lock(&dd->spin); 1193 dfly_changeqcpu_locked(lp, dd, rdd); 1194 spin_unlock(&dd->spin); 1195 } 1196 } 1197 1198 /* 1199 * Called from fork1() when a new child process is being created. 1200 * 1201 * Give the child process an initial estcpu that is more batch then 1202 * its parent and dock the parent for the fork (but do not 1203 * reschedule the parent). 1204 * 1205 * fast 1206 * 1207 * XXX lwp should be "spawning" instead of "forking" 1208 */ 1209 static void 1210 dfly_forking(struct lwp *plp, struct lwp *lp) 1211 { 1212 /* 1213 * Put the child 4 queue slots (out of 32) higher than the parent 1214 * (less desireable than the parent). 1215 */ 1216 lp->lwp_estcpu = ESTCPULIM(plp->lwp_estcpu + ESTCPUPPQ * 4); 1217 lp->lwp_forked = 1; 1218 lp->lwp_estfast = 0; 1219 1220 /* 1221 * Dock the parent a cost for the fork, protecting us from fork 1222 * bombs. If the parent is forking quickly make the child more 1223 * batchy. 1224 */ 1225 plp->lwp_estcpu = ESTCPULIM(plp->lwp_estcpu + ESTCPUPPQ / 16); 1226 } 1227 1228 /* 1229 * Called when a lwp is being removed from this scheduler, typically 1230 * during lwp_exit(). We have to clean out any ULOAD accounting before 1231 * we can let the lp go. The dd->spin lock is not needed for uload 1232 * updates. 1233 * 1234 * Scheduler dequeueing has already occurred, no further action in that 1235 * regard is needed. 1236 */ 1237 static void 1238 dfly_exiting(struct lwp *lp, struct proc *child_proc) 1239 { 1240 dfly_pcpu_t dd = &dfly_pcpu[lp->lwp_qcpu]; 1241 1242 if (lp->lwp_mpflags & LWP_MP_ULOAD) { 1243 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ULOAD); 1244 atomic_add_int(&dd->uload, -lp->lwp_uload); 1245 atomic_add_int(&dd->ucount, -1); 1246 atomic_add_int(&dfly_ucount, -1); 1247 } 1248 } 1249 1250 /* 1251 * This function cannot block in any way, but spinlocks are ok. 1252 * 1253 * Update the uload based on the state of the thread (whether it is going 1254 * to sleep or running again). The uload is meant to be a longer-term 1255 * load and not an instantanious load. 1256 */ 1257 static void 1258 dfly_uload_update(struct lwp *lp) 1259 { 1260 dfly_pcpu_t dd = &dfly_pcpu[lp->lwp_qcpu]; 1261 1262 if (lp->lwp_thread->td_flags & TDF_RUNQ) { 1263 if ((lp->lwp_mpflags & LWP_MP_ULOAD) == 0) { 1264 spin_lock(&dd->spin); 1265 if ((lp->lwp_mpflags & LWP_MP_ULOAD) == 0) { 1266 atomic_set_int(&lp->lwp_mpflags, 1267 LWP_MP_ULOAD); 1268 atomic_add_int(&dd->uload, lp->lwp_uload); 1269 atomic_add_int(&dd->ucount, 1); 1270 atomic_add_int(&dfly_ucount, 1); 1271 } 1272 spin_unlock(&dd->spin); 1273 } 1274 } else if (lp->lwp_slptime > 0) { 1275 if (lp->lwp_mpflags & LWP_MP_ULOAD) { 1276 spin_lock(&dd->spin); 1277 if (lp->lwp_mpflags & LWP_MP_ULOAD) { 1278 atomic_clear_int(&lp->lwp_mpflags, 1279 LWP_MP_ULOAD); 1280 atomic_add_int(&dd->uload, -lp->lwp_uload); 1281 atomic_add_int(&dd->ucount, -1); 1282 atomic_add_int(&dfly_ucount, -1); 1283 } 1284 spin_unlock(&dd->spin); 1285 } 1286 } 1287 } 1288 1289 /* 1290 * chooseproc() is called when a cpu needs a user process to LWKT schedule, 1291 * it selects a user process and returns it. If chklp is non-NULL and chklp 1292 * has a better or equal priority then the process that would otherwise be 1293 * chosen, NULL is returned. 1294 * 1295 * Until we fix the RUNQ code the chklp test has to be strict or we may 1296 * bounce between processes trying to acquire the current process designation. 1297 * 1298 * Must be called with rdd->spin locked. The spinlock is left intact through 1299 * the entire routine. dd->spin does not have to be locked. 1300 * 1301 * If worst is non-zero this function finds the worst thread instead of the 1302 * best thread (used by the schedulerclock-based rover). 1303 */ 1304 static 1305 struct lwp * 1306 dfly_chooseproc_locked(dfly_pcpu_t rdd, dfly_pcpu_t dd, 1307 struct lwp *chklp, int worst) 1308 { 1309 struct lwp *lp; 1310 struct rq *q; 1311 u_int32_t *which; 1312 u_int32_t pri; 1313 u_int32_t rtqbits; 1314 u_int32_t tsqbits; 1315 u_int32_t idqbits; 1316 1317 rtqbits = rdd->rtqueuebits; 1318 tsqbits = rdd->queuebits; 1319 idqbits = rdd->idqueuebits; 1320 1321 if (worst) { 1322 if (idqbits) { 1323 pri = bsrl(idqbits); 1324 q = &rdd->idqueues[pri]; 1325 which = &rdd->idqueuebits; 1326 } else if (tsqbits) { 1327 pri = bsrl(tsqbits); 1328 q = &rdd->queues[pri]; 1329 which = &rdd->queuebits; 1330 } else if (rtqbits) { 1331 pri = bsrl(rtqbits); 1332 q = &rdd->rtqueues[pri]; 1333 which = &rdd->rtqueuebits; 1334 } else { 1335 return (NULL); 1336 } 1337 lp = TAILQ_LAST(q, rq); 1338 } else { 1339 if (rtqbits) { 1340 pri = bsfl(rtqbits); 1341 q = &rdd->rtqueues[pri]; 1342 which = &rdd->rtqueuebits; 1343 } else if (tsqbits) { 1344 pri = bsfl(tsqbits); 1345 q = &rdd->queues[pri]; 1346 which = &rdd->queuebits; 1347 } else if (idqbits) { 1348 pri = bsfl(idqbits); 1349 q = &rdd->idqueues[pri]; 1350 which = &rdd->idqueuebits; 1351 } else { 1352 return (NULL); 1353 } 1354 lp = TAILQ_FIRST(q); 1355 } 1356 KASSERT(lp, ("chooseproc: no lwp on busy queue")); 1357 1358 /* 1359 * If the passed lwp <chklp> is reasonably close to the selected 1360 * lwp <lp>, return NULL (indicating that <chklp> should be kept). 1361 * 1362 * Note that we must error on the side of <chklp> to avoid bouncing 1363 * between threads in the acquire code. 1364 */ 1365 if (chklp) { 1366 if (chklp->lwp_priority < lp->lwp_priority + PPQ) 1367 return(NULL); 1368 } 1369 1370 KTR_COND_LOG(usched_chooseproc, 1371 lp->lwp_proc->p_pid == usched_dfly_pid_debug, 1372 lp->lwp_proc->p_pid, 1373 lp->lwp_thread->td_gd->gd_cpuid, 1374 mycpu->gd_cpuid); 1375 1376 KASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) != 0, ("not on runq6!")); 1377 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); 1378 TAILQ_REMOVE(q, lp, lwp_procq); 1379 --rdd->runqcount; 1380 if (TAILQ_EMPTY(q)) 1381 *which &= ~(1 << pri); 1382 1383 /* 1384 * If we are choosing a process from rdd with the intent to 1385 * move it to dd, lwp_qcpu must be adjusted while rdd's spinlock 1386 * is still held. 1387 */ 1388 if (rdd != dd) { 1389 if (lp->lwp_mpflags & LWP_MP_ULOAD) { 1390 atomic_add_int(&rdd->uload, -lp->lwp_uload); 1391 atomic_add_int(&rdd->ucount, -1); 1392 atomic_add_int(&dfly_ucount, -1); 1393 } 1394 lp->lwp_qcpu = dd->cpuid; 1395 atomic_add_int(&dd->uload, lp->lwp_uload); 1396 atomic_add_int(&dd->ucount, 1); 1397 atomic_add_int(&dfly_ucount, 1); 1398 atomic_set_int(&lp->lwp_mpflags, LWP_MP_ULOAD); 1399 } 1400 return lp; 1401 } 1402 1403 /* 1404 * USED TO PUSH RUNNABLE LWPS TO THE LEAST LOADED CPU. 1405 * 1406 * Choose a cpu node to schedule lp on, hopefully nearby its current 1407 * node. 1408 * 1409 * We give the current node a modest advantage for obvious reasons. 1410 * 1411 * We also give the node the thread was woken up FROM a slight advantage 1412 * in order to try to schedule paired threads which synchronize/block waiting 1413 * for each other fairly close to each other. Similarly in a network setting 1414 * this feature will also attempt to place a user process near the kernel 1415 * protocol thread that is feeding it data. THIS IS A CRITICAL PART of the 1416 * algorithm as it heuristically groups synchronizing processes for locality 1417 * of reference in multi-socket systems. 1418 * 1419 * We check against running processes and give a big advantage if there 1420 * are none running. 1421 * 1422 * The caller will normally dfly_setrunqueue() lp on the returned queue. 1423 * 1424 * When the topology is known choose a cpu whos group has, in aggregate, 1425 * has the lowest weighted load. 1426 */ 1427 static 1428 dfly_pcpu_t 1429 dfly_choose_best_queue(struct lwp *lp) 1430 { 1431 cpumask_t wakemask; 1432 cpumask_t mask; 1433 cpu_node_t *cpup; 1434 cpu_node_t *cpun; 1435 cpu_node_t *cpub; 1436 dfly_pcpu_t dd = &dfly_pcpu[lp->lwp_qcpu]; 1437 dfly_pcpu_t rdd; 1438 int wakecpu; 1439 int cpuid; 1440 int n; 1441 int count; 1442 int load; 1443 int lowest_load; 1444 1445 /* 1446 * When the topology is unknown choose a random cpu that is hopefully 1447 * idle. 1448 */ 1449 if (dd->cpunode == NULL) 1450 return (dfly_choose_queue_simple(dd, lp)); 1451 1452 /* 1453 * Pairing mask 1454 */ 1455 if ((wakecpu = lp->lwp_thread->td_wakefromcpu) >= 0) 1456 wakemask = dfly_pcpu[wakecpu].cpumask; 1457 else 1458 wakemask = 0; 1459 1460 /* 1461 * When the topology is known choose a cpu whos group has, in 1462 * aggregate, has the lowest weighted load. 1463 */ 1464 cpup = root_cpu_node; 1465 rdd = dd; 1466 1467 while (cpup) { 1468 /* 1469 * Degenerate case super-root 1470 */ 1471 if (cpup->child_no == 1) { 1472 cpup = cpup->child_node[0]; 1473 continue; 1474 } 1475 1476 /* 1477 * Terminal cpunode 1478 */ 1479 if (cpup->child_no == 0) { 1480 rdd = &dfly_pcpu[BSFCPUMASK(cpup->members)]; 1481 break; 1482 } 1483 1484 cpub = NULL; 1485 lowest_load = 0x7FFFFFFF; 1486 1487 for (n = 0; n < cpup->child_no; ++n) { 1488 /* 1489 * Accumulate load information for all cpus 1490 * which are members of this node. 1491 */ 1492 cpun = cpup->child_node[n]; 1493 mask = cpun->members & usched_global_cpumask & 1494 smp_active_mask & lp->lwp_cpumask; 1495 if (mask == 0) 1496 continue; 1497 1498 count = 0; 1499 load = 0; 1500 1501 while (mask) { 1502 cpuid = BSFCPUMASK(mask); 1503 rdd = &dfly_pcpu[cpuid]; 1504 load += rdd->uload; 1505 load += rdd->ucount * usched_dfly_weight3; 1506 1507 if (rdd->uschedcp == NULL && 1508 rdd->runqcount == 0 && 1509 globaldata_find(cpuid)->gd_tdrunqcount == 0 1510 ) { 1511 load -= usched_dfly_weight4; 1512 } 1513 #if 0 1514 else if (rdd->upri > lp->lwp_priority + PPQ) { 1515 load -= usched_dfly_weight4 / 2; 1516 } 1517 #endif 1518 mask &= ~CPUMASK(cpuid); 1519 ++count; 1520 } 1521 1522 /* 1523 * Compensate if the lp is already accounted for in 1524 * the aggregate uload for this mask set. We want 1525 * to calculate the loads as if lp were not present, 1526 * otherwise the calculation is bogus. 1527 */ 1528 if ((lp->lwp_mpflags & LWP_MP_ULOAD) && 1529 (dd->cpumask & cpun->members)) { 1530 load -= lp->lwp_uload; 1531 load -= usched_dfly_weight3; 1532 } 1533 1534 load /= count; 1535 1536 /* 1537 * Advantage the cpu group (lp) is already on. 1538 */ 1539 if (cpun->members & dd->cpumask) 1540 load -= usched_dfly_weight1; 1541 1542 /* 1543 * Advantage the cpu group we want to pair (lp) to, 1544 * but don't let it go to the exact same cpu as 1545 * the wakecpu target. 1546 * 1547 * We do this by checking whether cpun is a 1548 * terminal node or not. All cpun's at the same 1549 * level will either all be terminal or all not 1550 * terminal. 1551 * 1552 * If it is and we match we disadvantage the load. 1553 * If it is and we don't match we advantage the load. 1554 * 1555 * Also note that we are effectively disadvantaging 1556 * all-but-one by the same amount, so it won't effect 1557 * the weight1 factor for the all-but-one nodes. 1558 */ 1559 if (cpun->members & wakemask) { 1560 if (cpun->child_no != 0) { 1561 /* advantage */ 1562 load -= usched_dfly_weight2; 1563 } else { 1564 if (usched_dfly_features & 0x10) 1565 load += usched_dfly_weight2; 1566 else 1567 load -= usched_dfly_weight2; 1568 } 1569 } 1570 1571 /* 1572 * Calculate the best load 1573 */ 1574 if (cpub == NULL || lowest_load > load || 1575 (lowest_load == load && 1576 (cpun->members & dd->cpumask)) 1577 ) { 1578 lowest_load = load; 1579 cpub = cpun; 1580 } 1581 } 1582 cpup = cpub; 1583 } 1584 if (usched_dfly_chooser) 1585 kprintf("lp %02d->%02d %s\n", 1586 lp->lwp_qcpu, rdd->cpuid, lp->lwp_proc->p_comm); 1587 return (rdd); 1588 } 1589 1590 /* 1591 * USED TO PULL RUNNABLE LWPS FROM THE MOST LOADED CPU. 1592 * 1593 * Choose the worst queue close to dd's cpu node with a non-empty runq 1594 * that is NOT dd. Also require that the moving of the highest-load thread 1595 * from rdd to dd does not cause the uload's to cross each other. 1596 * 1597 * This is used by the thread chooser when the current cpu's queues are 1598 * empty to steal a thread from another cpu's queue. We want to offload 1599 * the most heavily-loaded queue. 1600 */ 1601 static 1602 dfly_pcpu_t 1603 dfly_choose_worst_queue(dfly_pcpu_t dd) 1604 { 1605 cpumask_t mask; 1606 cpu_node_t *cpup; 1607 cpu_node_t *cpun; 1608 cpu_node_t *cpub; 1609 dfly_pcpu_t rdd; 1610 int cpuid; 1611 int n; 1612 int count; 1613 int load; 1614 #if 0 1615 int pri; 1616 int hpri; 1617 #endif 1618 int highest_load; 1619 1620 /* 1621 * When the topology is unknown choose a random cpu that is hopefully 1622 * idle. 1623 */ 1624 if (dd->cpunode == NULL) { 1625 return (NULL); 1626 } 1627 1628 /* 1629 * When the topology is known choose a cpu whos group has, in 1630 * aggregate, has the lowest weighted load. 1631 */ 1632 cpup = root_cpu_node; 1633 rdd = dd; 1634 while (cpup) { 1635 /* 1636 * Degenerate case super-root 1637 */ 1638 if (cpup->child_no == 1) { 1639 cpup = cpup->child_node[0]; 1640 continue; 1641 } 1642 1643 /* 1644 * Terminal cpunode 1645 */ 1646 if (cpup->child_no == 0) { 1647 rdd = &dfly_pcpu[BSFCPUMASK(cpup->members)]; 1648 break; 1649 } 1650 1651 cpub = NULL; 1652 highest_load = 0; 1653 1654 for (n = 0; n < cpup->child_no; ++n) { 1655 /* 1656 * Accumulate load information for all cpus 1657 * which are members of this node. 1658 */ 1659 cpun = cpup->child_node[n]; 1660 mask = cpun->members & usched_global_cpumask & 1661 smp_active_mask; 1662 if (mask == 0) 1663 continue; 1664 count = 0; 1665 load = 0; 1666 1667 while (mask) { 1668 cpuid = BSFCPUMASK(mask); 1669 rdd = &dfly_pcpu[cpuid]; 1670 load += rdd->uload; 1671 load += rdd->ucount * usched_dfly_weight3; 1672 if (rdd->uschedcp == NULL && 1673 rdd->runqcount == 0 && 1674 globaldata_find(cpuid)->gd_tdrunqcount == 0 1675 ) { 1676 load -= usched_dfly_weight4; 1677 } 1678 #if 0 1679 else if (rdd->upri > dd->upri + PPQ) { 1680 load -= usched_dfly_weight4 / 2; 1681 } 1682 #endif 1683 mask &= ~CPUMASK(cpuid); 1684 ++count; 1685 } 1686 load /= count; 1687 1688 /* 1689 * Prefer candidates which are somewhat closer to 1690 * our cpu. 1691 */ 1692 if (dd->cpumask & cpun->members) 1693 load += usched_dfly_weight1; 1694 1695 /* 1696 * The best candidate is the one with the worst 1697 * (highest) load. 1698 */ 1699 if (cpub == NULL || highest_load < load) { 1700 highest_load = load; 1701 cpub = cpun; 1702 } 1703 } 1704 cpup = cpub; 1705 } 1706 1707 /* 1708 * We never return our own node (dd), and only return a remote 1709 * node if it's load is significantly worse than ours (i.e. where 1710 * stealing a thread would be considered reasonable). 1711 * 1712 * This also helps us avoid breaking paired threads apart which 1713 * can have disastrous effects on performance. 1714 */ 1715 if (rdd == dd) 1716 return(NULL); 1717 1718 #if 0 1719 hpri = 0; 1720 if (rdd->rtqueuebits && hpri < (pri = bsrl(rdd->rtqueuebits))) 1721 hpri = pri; 1722 if (rdd->queuebits && hpri < (pri = bsrl(rdd->queuebits))) 1723 hpri = pri; 1724 if (rdd->idqueuebits && hpri < (pri = bsrl(rdd->idqueuebits))) 1725 hpri = pri; 1726 hpri *= PPQ; 1727 if (rdd->uload - hpri < dd->uload + hpri) 1728 return(NULL); 1729 #endif 1730 return (rdd); 1731 } 1732 1733 static 1734 dfly_pcpu_t 1735 dfly_choose_queue_simple(dfly_pcpu_t dd, struct lwp *lp) 1736 { 1737 dfly_pcpu_t rdd; 1738 cpumask_t tmpmask; 1739 cpumask_t mask; 1740 int cpuid; 1741 1742 /* 1743 * Fallback to the original heuristic, select random cpu, 1744 * first checking cpus not currently running a user thread. 1745 */ 1746 ++dfly_scancpu; 1747 cpuid = (dfly_scancpu & 0xFFFF) % ncpus; 1748 mask = ~dfly_curprocmask & dfly_rdyprocmask & lp->lwp_cpumask & 1749 smp_active_mask & usched_global_cpumask; 1750 1751 while (mask) { 1752 tmpmask = ~(CPUMASK(cpuid) - 1); 1753 if (mask & tmpmask) 1754 cpuid = BSFCPUMASK(mask & tmpmask); 1755 else 1756 cpuid = BSFCPUMASK(mask); 1757 rdd = &dfly_pcpu[cpuid]; 1758 1759 if ((rdd->upri & ~PPQMASK) >= (lp->lwp_priority & ~PPQMASK)) 1760 goto found; 1761 mask &= ~CPUMASK(cpuid); 1762 } 1763 1764 /* 1765 * Then cpus which might have a currently running lp 1766 */ 1767 cpuid = (dfly_scancpu & 0xFFFF) % ncpus; 1768 mask = dfly_curprocmask & dfly_rdyprocmask & 1769 lp->lwp_cpumask & smp_active_mask & usched_global_cpumask; 1770 1771 while (mask) { 1772 tmpmask = ~(CPUMASK(cpuid) - 1); 1773 if (mask & tmpmask) 1774 cpuid = BSFCPUMASK(mask & tmpmask); 1775 else 1776 cpuid = BSFCPUMASK(mask); 1777 rdd = &dfly_pcpu[cpuid]; 1778 1779 if ((rdd->upri & ~PPQMASK) > (lp->lwp_priority & ~PPQMASK)) 1780 goto found; 1781 mask &= ~CPUMASK(cpuid); 1782 } 1783 1784 /* 1785 * If we cannot find a suitable cpu we reload from dfly_scancpu 1786 * and round-robin. Other cpus will pickup as they release their 1787 * current lwps or become ready. 1788 * 1789 * Avoid a degenerate system lockup case if usched_global_cpumask 1790 * is set to 0 or otherwise does not cover lwp_cpumask. 1791 * 1792 * We only kick the target helper thread in this case, we do not 1793 * set the user resched flag because 1794 */ 1795 cpuid = (dfly_scancpu & 0xFFFF) % ncpus; 1796 if ((CPUMASK(cpuid) & usched_global_cpumask) == 0) 1797 cpuid = 0; 1798 rdd = &dfly_pcpu[cpuid]; 1799 found: 1800 return (rdd); 1801 } 1802 1803 static 1804 void 1805 dfly_need_user_resched_remote(void *dummy) 1806 { 1807 globaldata_t gd = mycpu; 1808 dfly_pcpu_t dd = &dfly_pcpu[gd->gd_cpuid]; 1809 1810 /* 1811 * Flag reschedule needed 1812 */ 1813 need_user_resched(); 1814 1815 /* 1816 * If no user thread is currently running we need to kick the helper 1817 * on our cpu to recover. Otherwise the cpu will never schedule 1818 * anything again. 1819 * 1820 * We cannot schedule the process ourselves because this is an 1821 * IPI callback and we cannot acquire spinlocks in an IPI callback. 1822 * 1823 * Call wakeup_mycpu to avoid sending IPIs to other CPUs 1824 */ 1825 if (dd->uschedcp == NULL && (dfly_rdyprocmask & gd->gd_cpumask)) { 1826 atomic_clear_cpumask(&dfly_rdyprocmask, gd->gd_cpumask); 1827 wakeup_mycpu(&dd->helper_thread); 1828 } 1829 } 1830 1831 /* 1832 * dfly_remrunqueue_locked() removes a given process from the run queue 1833 * that it is on, clearing the queue busy bit if it becomes empty. 1834 * 1835 * Note that user process scheduler is different from the LWKT schedule. 1836 * The user process scheduler only manages user processes but it uses LWKT 1837 * underneath, and a user process operating in the kernel will often be 1838 * 'released' from our management. 1839 * 1840 * uload is NOT adjusted here. It is only adjusted if the lwkt_thread goes 1841 * to sleep or the lwp is moved to a different runq. 1842 */ 1843 static void 1844 dfly_remrunqueue_locked(dfly_pcpu_t rdd, struct lwp *lp) 1845 { 1846 struct rq *q; 1847 u_int32_t *which; 1848 u_int8_t pri; 1849 1850 KKASSERT(rdd->runqcount >= 0); 1851 1852 pri = lp->lwp_rqindex; 1853 1854 switch(lp->lwp_rqtype) { 1855 case RTP_PRIO_NORMAL: 1856 q = &rdd->queues[pri]; 1857 which = &rdd->queuebits; 1858 break; 1859 case RTP_PRIO_REALTIME: 1860 case RTP_PRIO_FIFO: 1861 q = &rdd->rtqueues[pri]; 1862 which = &rdd->rtqueuebits; 1863 break; 1864 case RTP_PRIO_IDLE: 1865 q = &rdd->idqueues[pri]; 1866 which = &rdd->idqueuebits; 1867 break; 1868 default: 1869 panic("remrunqueue: invalid rtprio type"); 1870 /* NOT REACHED */ 1871 } 1872 KKASSERT(lp->lwp_mpflags & LWP_MP_ONRUNQ); 1873 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); 1874 TAILQ_REMOVE(q, lp, lwp_procq); 1875 --rdd->runqcount; 1876 if (TAILQ_EMPTY(q)) { 1877 KASSERT((*which & (1 << pri)) != 0, 1878 ("remrunqueue: remove from empty queue")); 1879 *which &= ~(1 << pri); 1880 } 1881 } 1882 1883 /* 1884 * dfly_setrunqueue_locked() 1885 * 1886 * Add a process whos rqtype and rqindex had previously been calculated 1887 * onto the appropriate run queue. Determine if the addition requires 1888 * a reschedule on a cpu and return the cpuid or -1. 1889 * 1890 * NOTE: Lower priorities are better priorities. 1891 * 1892 * NOTE ON ULOAD: This variable specifies the aggregate load on a cpu, the 1893 * sum of the rough lwp_priority for all running and runnable 1894 * processes. Lower priority processes (higher lwp_priority 1895 * values) actually DO count as more load, not less, because 1896 * these are the programs which require the most care with 1897 * regards to cpu selection. 1898 */ 1899 static void 1900 dfly_setrunqueue_locked(dfly_pcpu_t rdd, struct lwp *lp) 1901 { 1902 struct rq *q; 1903 u_int32_t *which; 1904 int pri; 1905 1906 KKASSERT(lp->lwp_qcpu == rdd->cpuid); 1907 1908 if ((lp->lwp_mpflags & LWP_MP_ULOAD) == 0) { 1909 atomic_set_int(&lp->lwp_mpflags, LWP_MP_ULOAD); 1910 atomic_add_int(&dfly_pcpu[lp->lwp_qcpu].uload, lp->lwp_uload); 1911 atomic_add_int(&dfly_pcpu[lp->lwp_qcpu].ucount, 1); 1912 atomic_add_int(&dfly_ucount, 1); 1913 } 1914 1915 pri = lp->lwp_rqindex; 1916 1917 switch(lp->lwp_rqtype) { 1918 case RTP_PRIO_NORMAL: 1919 q = &rdd->queues[pri]; 1920 which = &rdd->queuebits; 1921 break; 1922 case RTP_PRIO_REALTIME: 1923 case RTP_PRIO_FIFO: 1924 q = &rdd->rtqueues[pri]; 1925 which = &rdd->rtqueuebits; 1926 break; 1927 case RTP_PRIO_IDLE: 1928 q = &rdd->idqueues[pri]; 1929 which = &rdd->idqueuebits; 1930 break; 1931 default: 1932 panic("remrunqueue: invalid rtprio type"); 1933 /* NOT REACHED */ 1934 } 1935 1936 /* 1937 * Place us on the selected queue. Determine if we should be 1938 * placed at the head of the queue or at the end. 1939 * 1940 * We are placed at the tail if our round-robin count has expired, 1941 * or is about to expire and the system thinks its a good place to 1942 * round-robin, or there is already a next thread on the queue 1943 * (it might be trying to pick up where it left off and we don't 1944 * want to interfere). 1945 */ 1946 KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); 1947 atomic_set_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); 1948 ++rdd->runqcount; 1949 1950 if (lp->lwp_rrcount >= usched_dfly_rrinterval || 1951 (lp->lwp_rrcount >= usched_dfly_rrinterval / 2 && 1952 (lp->lwp_thread->td_mpflags & TDF_MP_BATCH_DEMARC)) || 1953 !TAILQ_EMPTY(q) 1954 ) { 1955 atomic_clear_int(&lp->lwp_thread->td_mpflags, 1956 TDF_MP_BATCH_DEMARC); 1957 lp->lwp_rrcount = 0; 1958 TAILQ_INSERT_TAIL(q, lp, lwp_procq); 1959 } else { 1960 if (TAILQ_EMPTY(q)) 1961 lp->lwp_rrcount = 0; 1962 TAILQ_INSERT_HEAD(q, lp, lwp_procq); 1963 } 1964 *which |= 1 << pri; 1965 } 1966 1967 /* 1968 * For SMP systems a user scheduler helper thread is created for each 1969 * cpu and is used to allow one cpu to wakeup another for the purposes of 1970 * scheduling userland threads from setrunqueue(). 1971 * 1972 * UP systems do not need the helper since there is only one cpu. 1973 * 1974 * We can't use the idle thread for this because we might block. 1975 * Additionally, doing things this way allows us to HLT idle cpus 1976 * on MP systems. 1977 */ 1978 static void 1979 dfly_helper_thread(void *dummy) 1980 { 1981 globaldata_t gd; 1982 dfly_pcpu_t dd; 1983 dfly_pcpu_t rdd; 1984 struct lwp *nlp; 1985 cpumask_t mask; 1986 int cpuid; 1987 1988 gd = mycpu; 1989 cpuid = gd->gd_cpuid; /* doesn't change */ 1990 mask = gd->gd_cpumask; /* doesn't change */ 1991 dd = &dfly_pcpu[cpuid]; 1992 1993 /* 1994 * Since we only want to be woken up only when no user processes 1995 * are scheduled on a cpu, run at an ultra low priority. 1996 */ 1997 lwkt_setpri_self(TDPRI_USER_SCHEDULER); 1998 1999 tsleep(&dd->helper_thread, 0, "schslp", 0); 2000 2001 for (;;) { 2002 /* 2003 * We use the LWKT deschedule-interlock trick to avoid racing 2004 * dfly_rdyprocmask. This means we cannot block through to the 2005 * manual lwkt_switch() call we make below. 2006 */ 2007 crit_enter_gd(gd); 2008 tsleep_interlock(&dd->helper_thread, 0); 2009 2010 spin_lock(&dd->spin); 2011 2012 atomic_set_cpumask(&dfly_rdyprocmask, mask); 2013 clear_user_resched(); /* This satisfied the reschedule request */ 2014 #if 0 2015 dd->rrcount = 0; /* Reset the round-robin counter */ 2016 #endif 2017 2018 if (dd->runqcount || dd->uschedcp != NULL) { 2019 /* 2020 * Threads are available. A thread may or may not be 2021 * currently scheduled. Get the best thread already queued 2022 * to this cpu. 2023 */ 2024 nlp = dfly_chooseproc_locked(dd, dd, dd->uschedcp, 0); 2025 if (nlp) { 2026 atomic_set_cpumask(&dfly_curprocmask, mask); 2027 dd->upri = nlp->lwp_priority; 2028 dd->uschedcp = nlp; 2029 #if 0 2030 dd->rrcount = 0; /* reset round robin */ 2031 #endif 2032 spin_unlock(&dd->spin); 2033 lwkt_acquire(nlp->lwp_thread); 2034 lwkt_schedule(nlp->lwp_thread); 2035 } else { 2036 /* 2037 * This situation should not occur because we had 2038 * at least one thread available. 2039 */ 2040 spin_unlock(&dd->spin); 2041 } 2042 } else if (usched_dfly_features & 0x01) { 2043 /* 2044 * This cpu is devoid of runnable threads, steal a thread 2045 * from another cpu. Since we're stealing, might as well 2046 * load balance at the same time. 2047 * 2048 * We choose the highest-loaded thread from the worst queue. 2049 * 2050 * NOTE! This function only returns a non-NULL rdd when 2051 * another cpu's queue is obviously overloaded. We 2052 * do not want to perform the type of rebalancing 2053 * the schedclock does here because it would result 2054 * in insane process pulling when 'steady' state is 2055 * partially unbalanced (e.g. 6 runnables and only 2056 * 4 cores). 2057 */ 2058 rdd = dfly_choose_worst_queue(dd); 2059 if (rdd && spin_trylock(&rdd->spin)) { 2060 nlp = dfly_chooseproc_locked(rdd, dd, NULL, 1); 2061 spin_unlock(&rdd->spin); 2062 } else { 2063 nlp = NULL; 2064 } 2065 if (nlp) { 2066 atomic_set_cpumask(&dfly_curprocmask, mask); 2067 dd->upri = nlp->lwp_priority; 2068 dd->uschedcp = nlp; 2069 #if 0 2070 dd->rrcount = 0; /* reset round robin */ 2071 #endif 2072 spin_unlock(&dd->spin); 2073 lwkt_acquire(nlp->lwp_thread); 2074 lwkt_schedule(nlp->lwp_thread); 2075 } else { 2076 /* 2077 * Leave the thread on our run queue. Another 2078 * scheduler will try to pull it later. 2079 */ 2080 spin_unlock(&dd->spin); 2081 } 2082 } else { 2083 /* 2084 * devoid of runnable threads and not allowed to steal 2085 * any. 2086 */ 2087 spin_unlock(&dd->spin); 2088 } 2089 2090 /* 2091 * We're descheduled unless someone scheduled us. Switch away. 2092 * Exiting the critical section will cause splz() to be called 2093 * for us if interrupts and such are pending. 2094 */ 2095 crit_exit_gd(gd); 2096 tsleep(&dd->helper_thread, PINTERLOCKED, "schslp", 0); 2097 } 2098 } 2099 2100 #if 0 2101 static int 2102 sysctl_usched_dfly_stick_to_level(SYSCTL_HANDLER_ARGS) 2103 { 2104 int error, new_val; 2105 2106 new_val = usched_dfly_stick_to_level; 2107 2108 error = sysctl_handle_int(oidp, &new_val, 0, req); 2109 if (error != 0 || req->newptr == NULL) 2110 return (error); 2111 if (new_val > cpu_topology_levels_number - 1 || new_val < 0) 2112 return (EINVAL); 2113 usched_dfly_stick_to_level = new_val; 2114 return (0); 2115 } 2116 #endif 2117 2118 /* 2119 * Setup the queues and scheduler helpers (scheduler helpers are SMP only). 2120 * Note that curprocmask bit 0 has already been cleared by rqinit() and 2121 * we should not mess with it further. 2122 */ 2123 static void 2124 usched_dfly_cpu_init(void) 2125 { 2126 int i; 2127 int j; 2128 int cpuid; 2129 int smt_not_supported = 0; 2130 int cache_coherent_not_supported = 0; 2131 2132 if (bootverbose) 2133 kprintf("Start scheduler helpers on cpus:\n"); 2134 2135 sysctl_ctx_init(&usched_dfly_sysctl_ctx); 2136 usched_dfly_sysctl_tree = 2137 SYSCTL_ADD_NODE(&usched_dfly_sysctl_ctx, 2138 SYSCTL_STATIC_CHILDREN(_kern), OID_AUTO, 2139 "usched_dfly", CTLFLAG_RD, 0, ""); 2140 2141 for (i = 0; i < ncpus; ++i) { 2142 dfly_pcpu_t dd = &dfly_pcpu[i]; 2143 cpumask_t mask = CPUMASK(i); 2144 2145 if ((mask & smp_active_mask) == 0) 2146 continue; 2147 2148 spin_init(&dd->spin); 2149 dd->cpunode = get_cpu_node_by_cpuid(i); 2150 dd->cpuid = i; 2151 dd->cpumask = CPUMASK(i); 2152 for (j = 0; j < NQS; j++) { 2153 TAILQ_INIT(&dd->queues[j]); 2154 TAILQ_INIT(&dd->rtqueues[j]); 2155 TAILQ_INIT(&dd->idqueues[j]); 2156 } 2157 atomic_clear_cpumask(&dfly_curprocmask, 1); 2158 2159 if (dd->cpunode == NULL) { 2160 smt_not_supported = 1; 2161 cache_coherent_not_supported = 1; 2162 if (bootverbose) 2163 kprintf ("\tcpu%d - WARNING: No CPU NODE " 2164 "found for cpu\n", i); 2165 } else { 2166 switch (dd->cpunode->type) { 2167 case THREAD_LEVEL: 2168 if (bootverbose) 2169 kprintf ("\tcpu%d - HyperThreading " 2170 "available. Core siblings: ", 2171 i); 2172 break; 2173 case CORE_LEVEL: 2174 smt_not_supported = 1; 2175 2176 if (bootverbose) 2177 kprintf ("\tcpu%d - No HT available, " 2178 "multi-core/physical " 2179 "cpu. Physical siblings: ", 2180 i); 2181 break; 2182 case CHIP_LEVEL: 2183 smt_not_supported = 1; 2184 2185 if (bootverbose) 2186 kprintf ("\tcpu%d - No HT available, " 2187 "single-core/physical cpu. " 2188 "Package Siblings: ", 2189 i); 2190 break; 2191 default: 2192 /* Let's go for safe defaults here */ 2193 smt_not_supported = 1; 2194 cache_coherent_not_supported = 1; 2195 if (bootverbose) 2196 kprintf ("\tcpu%d - Unknown cpunode->" 2197 "type=%u. Siblings: ", 2198 i, 2199 (u_int)dd->cpunode->type); 2200 break; 2201 } 2202 2203 if (bootverbose) { 2204 if (dd->cpunode->parent_node != NULL) { 2205 CPUSET_FOREACH(cpuid, dd->cpunode->parent_node->members) 2206 kprintf("cpu%d ", cpuid); 2207 kprintf("\n"); 2208 } else { 2209 kprintf(" no siblings\n"); 2210 } 2211 } 2212 } 2213 2214 lwkt_create(dfly_helper_thread, NULL, NULL, &dd->helper_thread, 2215 0, i, "usched %d", i); 2216 2217 /* 2218 * Allow user scheduling on the target cpu. cpu #0 has already 2219 * been enabled in rqinit(). 2220 */ 2221 if (i) 2222 atomic_clear_cpumask(&dfly_curprocmask, mask); 2223 atomic_set_cpumask(&dfly_rdyprocmask, mask); 2224 dd->upri = PRIBASE_NULL; 2225 2226 } 2227 2228 /* usched_dfly sysctl configurable parameters */ 2229 2230 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2231 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2232 OID_AUTO, "rrinterval", CTLFLAG_RW, 2233 &usched_dfly_rrinterval, 0, ""); 2234 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2235 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2236 OID_AUTO, "decay", CTLFLAG_RW, 2237 &usched_dfly_decay, 0, "Extra decay when not running"); 2238 2239 /* Add enable/disable option for SMT scheduling if supported */ 2240 if (smt_not_supported) { 2241 usched_dfly_smt = 0; 2242 SYSCTL_ADD_STRING(&usched_dfly_sysctl_ctx, 2243 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2244 OID_AUTO, "smt", CTLFLAG_RD, 2245 "NOT SUPPORTED", 0, "SMT NOT SUPPORTED"); 2246 } else { 2247 usched_dfly_smt = 1; 2248 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2249 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2250 OID_AUTO, "smt", CTLFLAG_RW, 2251 &usched_dfly_smt, 0, "Enable SMT scheduling"); 2252 } 2253 2254 /* 2255 * Add enable/disable option for cache coherent scheduling 2256 * if supported 2257 */ 2258 if (cache_coherent_not_supported) { 2259 usched_dfly_cache_coherent = 0; 2260 SYSCTL_ADD_STRING(&usched_dfly_sysctl_ctx, 2261 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2262 OID_AUTO, "cache_coherent", CTLFLAG_RD, 2263 "NOT SUPPORTED", 0, 2264 "Cache coherence NOT SUPPORTED"); 2265 } else { 2266 usched_dfly_cache_coherent = 1; 2267 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2268 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2269 OID_AUTO, "cache_coherent", CTLFLAG_RW, 2270 &usched_dfly_cache_coherent, 0, 2271 "Enable/Disable cache coherent scheduling"); 2272 2273 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2274 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2275 OID_AUTO, "weight1", CTLFLAG_RW, 2276 &usched_dfly_weight1, 200, 2277 "Weight selection for current cpu"); 2278 2279 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2280 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2281 OID_AUTO, "weight2", CTLFLAG_RW, 2282 &usched_dfly_weight2, 180, 2283 "Weight selection for wakefrom cpu"); 2284 2285 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2286 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2287 OID_AUTO, "weight3", CTLFLAG_RW, 2288 &usched_dfly_weight3, 40, 2289 "Weight selection for num threads on queue"); 2290 2291 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2292 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2293 OID_AUTO, "weight4", CTLFLAG_RW, 2294 &usched_dfly_weight4, 160, 2295 "Availability of other idle cpus"); 2296 2297 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2298 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2299 OID_AUTO, "fast_resched", CTLFLAG_RW, 2300 &usched_dfly_fast_resched, 0, 2301 "Availability of other idle cpus"); 2302 2303 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2304 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2305 OID_AUTO, "features", CTLFLAG_RW, 2306 &usched_dfly_features, 0x8F, 2307 "Allow pulls into empty queues"); 2308 2309 SYSCTL_ADD_INT(&usched_dfly_sysctl_ctx, 2310 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2311 OID_AUTO, "swmask", CTLFLAG_RW, 2312 &usched_dfly_swmask, ~PPQMASK, 2313 "Queue mask to force thread switch"); 2314 2315 #if 0 2316 SYSCTL_ADD_PROC(&usched_dfly_sysctl_ctx, 2317 SYSCTL_CHILDREN(usched_dfly_sysctl_tree), 2318 OID_AUTO, "stick_to_level", 2319 CTLTYPE_INT | CTLFLAG_RW, 2320 NULL, sizeof usched_dfly_stick_to_level, 2321 sysctl_usched_dfly_stick_to_level, "I", 2322 "Stick a process to this level. See sysctl" 2323 "paremter hw.cpu_topology.level_description"); 2324 #endif 2325 } 2326 } 2327 SYSINIT(uschedtd, SI_BOOT2_USCHED, SI_ORDER_SECOND, 2328 usched_dfly_cpu_init, NULL) 2329