1 /* 2 * Copyright (c) 2006 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * $DragonFly: src/sys/kern/usched_dummy.c,v 1.9 2008/04/21 15:24:46 dillon Exp $ 35 */ 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 <machine/cpu.h> 49 #include <machine/smp.h> 50 51 #include <sys/thread2.h> 52 #include <sys/spinlock2.h> 53 #include <sys/mplock2.h> 54 55 #define MAXPRI 128 56 #define PRIBASE_REALTIME 0 57 #define PRIBASE_NORMAL MAXPRI 58 #define PRIBASE_IDLE (MAXPRI * 2) 59 #define PRIBASE_THREAD (MAXPRI * 3) 60 #define PRIBASE_NULL (MAXPRI * 4) 61 62 #define lwp_priority lwp_usdata.bsd4.priority 63 #define lwp_estcpu lwp_usdata.bsd4.estcpu 64 65 static void dummy_acquire_curproc(struct lwp *lp); 66 static void dummy_release_curproc(struct lwp *lp); 67 static void dummy_select_curproc(globaldata_t gd); 68 static void dummy_setrunqueue(struct lwp *lp); 69 static void dummy_schedulerclock(struct lwp *lp, sysclock_t period, 70 sysclock_t cpstamp); 71 static void dummy_recalculate_estcpu(struct lwp *lp); 72 static void dummy_resetpriority(struct lwp *lp); 73 static void dummy_forking(struct lwp *plp, struct lwp *lp); 74 static void dummy_exiting(struct lwp *plp, struct proc *child); 75 static void dummy_uload_update(struct lwp *lp); 76 static void dummy_yield(struct lwp *lp); 77 78 struct usched usched_dummy = { 79 { NULL }, 80 "dummy", "Dummy DragonFly Scheduler", 81 NULL, /* default registration */ 82 NULL, /* default deregistration */ 83 dummy_acquire_curproc, 84 dummy_release_curproc, 85 dummy_setrunqueue, 86 dummy_schedulerclock, 87 dummy_recalculate_estcpu, 88 dummy_resetpriority, 89 dummy_forking, 90 dummy_exiting, 91 dummy_uload_update, 92 NULL, /* setcpumask not supported */ 93 dummy_yield 94 }; 95 96 struct usched_dummy_pcpu { 97 int rrcount; 98 struct thread helper_thread; 99 struct lwp *uschedcp; 100 }; 101 102 typedef struct usched_dummy_pcpu *dummy_pcpu_t; 103 104 static struct usched_dummy_pcpu dummy_pcpu[MAXCPU]; 105 static cpumask_t dummy_curprocmask = -1; 106 static cpumask_t dummy_rdyprocmask; 107 static struct spinlock dummy_spin; 108 static TAILQ_HEAD(rq, lwp) dummy_runq; 109 static int dummy_runqcount; 110 111 static int usched_dummy_rrinterval = (ESTCPUFREQ + 9) / 10; 112 SYSCTL_INT(_kern, OID_AUTO, usched_dummy_rrinterval, CTLFLAG_RW, 113 &usched_dummy_rrinterval, 0, ""); 114 115 /* 116 * Initialize the run queues at boot time, clear cpu 0 in curprocmask 117 * to allow dummy scheduling on cpu 0. 118 */ 119 static void 120 dummyinit(void *dummy) 121 { 122 TAILQ_INIT(&dummy_runq); 123 spin_init(&dummy_spin); 124 atomic_clear_cpumask(&dummy_curprocmask, 1); 125 } 126 SYSINIT(runqueue, SI_BOOT2_USCHED, SI_ORDER_FIRST, dummyinit, NULL) 127 128 /* 129 * DUMMY_ACQUIRE_CURPROC 130 * 131 * This function is called when the kernel intends to return to userland. 132 * It is responsible for making the thread the current designated userland 133 * thread for this cpu, blocking if necessary. 134 * 135 * The kernel will not depress our LWKT priority until after we return, 136 * in case we have to shove over to another cpu. 137 * 138 * We must determine our thread's disposition before we switch away. This 139 * is very sensitive code. 140 * 141 * We are expected to handle userland reschedule requests here too. 142 * 143 * WARNING! THIS FUNCTION IS ALLOWED TO CAUSE THE CURRENT THREAD TO MIGRATE 144 * TO ANOTHER CPU! Because most of the kernel assumes that no migration will 145 * occur, this function is called only under very controlled circumstances. 146 * 147 * MPSAFE 148 */ 149 static void 150 dummy_acquire_curproc(struct lwp *lp) 151 { 152 globaldata_t gd = mycpu; 153 dummy_pcpu_t dd = &dummy_pcpu[gd->gd_cpuid]; 154 thread_t td = lp->lwp_thread; 155 156 /* 157 * Possibly select another thread 158 */ 159 if (user_resched_wanted()) 160 dummy_select_curproc(gd); 161 162 /* 163 * If this cpu has no current thread, select ourself 164 */ 165 if (dd->uschedcp == lp || 166 (dd->uschedcp == NULL && TAILQ_EMPTY(&dummy_runq))) { 167 atomic_set_cpumask(&dummy_curprocmask, gd->gd_cpumask); 168 dd->uschedcp = lp; 169 return; 170 } 171 172 /* 173 * If this cpu's current user process thread is not our thread, 174 * deschedule ourselves and place us on the run queue, then 175 * switch away. 176 * 177 * We loop until we become the current process. Its a good idea 178 * to run any passive release(s) before we mess with the scheduler 179 * so our thread is in the expected state. 180 */ 181 KKASSERT(dd->uschedcp != lp); 182 if (td->td_release) 183 td->td_release(lp->lwp_thread); 184 do { 185 crit_enter(); 186 lwkt_deschedule_self(td); 187 dummy_setrunqueue(lp); 188 if ((td->td_flags & TDF_RUNQ) == 0) 189 ++lp->lwp_ru.ru_nivcsw; 190 lwkt_switch(); /* WE MAY MIGRATE TO ANOTHER CPU */ 191 crit_exit(); 192 gd = mycpu; 193 dd = &dummy_pcpu[gd->gd_cpuid]; 194 KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); 195 } while (dd->uschedcp != lp); 196 } 197 198 /* 199 * DUMMY_RELEASE_CURPROC 200 * 201 * This routine detaches the current thread from the userland scheduler, 202 * usually because the thread needs to run in the kernel (at kernel priority) 203 * for a while. 204 * 205 * This routine is also responsible for selecting a new thread to 206 * make the current thread. 207 * 208 * MPSAFE 209 */ 210 static void 211 dummy_release_curproc(struct lwp *lp) 212 { 213 globaldata_t gd = mycpu; 214 dummy_pcpu_t dd = &dummy_pcpu[gd->gd_cpuid]; 215 216 KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); 217 if (dd->uschedcp == lp) { 218 dummy_select_curproc(gd); 219 } 220 } 221 222 /* 223 * DUMMY_SELECT_CURPROC 224 * 225 * Select a new current process for this cpu. This satisfies a user 226 * scheduler reschedule request so clear that too. 227 * 228 * This routine is also responsible for equal-priority round-robining, 229 * typically triggered from dummy_schedulerclock(). In our dummy example 230 * all the 'user' threads are LWKT scheduled all at once and we just 231 * call lwkt_switch(). 232 * 233 * MPSAFE 234 */ 235 static 236 void 237 dummy_select_curproc(globaldata_t gd) 238 { 239 dummy_pcpu_t dd = &dummy_pcpu[gd->gd_cpuid]; 240 struct lwp *lp; 241 242 clear_user_resched(); 243 spin_lock(&dummy_spin); 244 if ((lp = TAILQ_FIRST(&dummy_runq)) == NULL) { 245 dd->uschedcp = NULL; 246 atomic_clear_cpumask(&dummy_curprocmask, gd->gd_cpumask); 247 spin_unlock(&dummy_spin); 248 } else { 249 --dummy_runqcount; 250 TAILQ_REMOVE(&dummy_runq, lp, lwp_procq); 251 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); 252 dd->uschedcp = lp; 253 atomic_set_cpumask(&dummy_curprocmask, gd->gd_cpumask); 254 spin_unlock(&dummy_spin); 255 #ifdef SMP 256 lwkt_acquire(lp->lwp_thread); 257 #endif 258 lwkt_schedule(lp->lwp_thread); 259 } 260 } 261 262 /* 263 * DUMMY_SETRUNQUEUE 264 * 265 * This routine is called to schedule a new user process after a fork. 266 * The scheduler module itself might also call this routine to place 267 * the current process on the userland scheduler's run queue prior 268 * to calling dummy_select_curproc(). 269 * 270 * The caller may set LWP_PASSIVE_ACQ in lwp_flags to indicate that we should 271 * attempt to leave the thread on the current cpu. 272 * 273 * MPSAFE 274 */ 275 static void 276 dummy_setrunqueue(struct lwp *lp) 277 { 278 globaldata_t gd = mycpu; 279 dummy_pcpu_t dd = &dummy_pcpu[gd->gd_cpuid]; 280 cpumask_t mask; 281 int cpuid; 282 283 if (dd->uschedcp == NULL) { 284 dd->uschedcp = lp; 285 atomic_set_cpumask(&dummy_curprocmask, gd->gd_cpumask); 286 lwkt_schedule(lp->lwp_thread); 287 } else { 288 /* 289 * Add to our global runq 290 */ 291 KKASSERT((lp->lwp_mpflags & LWP_MP_ONRUNQ) == 0); 292 spin_lock(&dummy_spin); 293 ++dummy_runqcount; 294 TAILQ_INSERT_TAIL(&dummy_runq, lp, lwp_procq); 295 atomic_set_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); 296 #ifdef SMP 297 lwkt_giveaway(lp->lwp_thread); 298 #endif 299 300 /* lp = TAILQ_FIRST(&dummy_runq); */ 301 302 /* 303 * Notify the next available cpu. P.S. some 304 * cpu affinity could be done here. 305 * 306 * The rdyprocmask bit placeholds the knowledge that there 307 * is a process on the runq that needs service. If the 308 * helper thread cannot find a home for it it will forward 309 * the request to another available cpu. 310 */ 311 mask = ~dummy_curprocmask & dummy_rdyprocmask & 312 gd->gd_other_cpus; 313 if (mask) { 314 cpuid = BSFCPUMASK(mask); 315 atomic_clear_cpumask(&dummy_rdyprocmask, CPUMASK(cpuid)); 316 spin_unlock(&dummy_spin); 317 lwkt_schedule(&dummy_pcpu[cpuid].helper_thread); 318 } else { 319 spin_unlock(&dummy_spin); 320 } 321 } 322 } 323 324 /* 325 * This routine is called from a systimer IPI. It must NEVER block. 326 * If a lwp compatible with this scheduler is the currently running 327 * thread this function is called with a non-NULL lp, otherwise it 328 * will be called with a NULL lp. 329 * 330 * This routine is called at ESTCPUFREQ on each cpu independantly. 331 * 332 * This routine typically queues a reschedule request, which will cause 333 * the scheduler's BLAH_select_curproc() to be called as soon as possible. 334 */ 335 static 336 void 337 dummy_schedulerclock(struct lwp *lp, sysclock_t period, sysclock_t cpstamp) 338 { 339 globaldata_t gd = mycpu; 340 dummy_pcpu_t dd = &dummy_pcpu[gd->gd_cpuid]; 341 342 if (lp == NULL) 343 return; 344 345 if (++dd->rrcount >= usched_dummy_rrinterval) { 346 dd->rrcount = 0; 347 need_user_resched(); 348 } 349 } 350 351 /* 352 * DUMMY_RECALCULATE_ESTCPU 353 * 354 * Called once a second for any process that is running or has slept 355 * for less then 2 seconds. 356 * 357 * MPSAFE 358 */ 359 static 360 void 361 dummy_recalculate_estcpu(struct lwp *lp) 362 { 363 } 364 365 /* 366 * MPSAFE 367 */ 368 static 369 void 370 dummy_yield(struct lwp *lp) 371 { 372 need_user_resched(); 373 } 374 375 /* 376 * DUMMY_RESETPRIORITY 377 * 378 * This routine is called after the kernel has potentially modified 379 * the lwp_rtprio structure. The target process may be running or sleeping 380 * or scheduled but not yet running or owned by another cpu. Basically, 381 * it can be in virtually any state. 382 * 383 * This routine is called by fork1() for initial setup with the process 384 * of the run queue, and also may be called normally with the process on or 385 * off the run queue. 386 * 387 * MPSAFE 388 */ 389 static void 390 dummy_resetpriority(struct lwp *lp) 391 { 392 /* XXX spinlock usually needed */ 393 /* 394 * Set p_priority for general process comparisons 395 */ 396 switch(lp->lwp_rtprio.type) { 397 case RTP_PRIO_REALTIME: 398 lp->lwp_priority = PRIBASE_REALTIME + lp->lwp_rtprio.prio; 399 return; 400 case RTP_PRIO_NORMAL: 401 lp->lwp_priority = PRIBASE_NORMAL + lp->lwp_rtprio.prio; 402 break; 403 case RTP_PRIO_IDLE: 404 lp->lwp_priority = PRIBASE_IDLE + lp->lwp_rtprio.prio; 405 return; 406 case RTP_PRIO_THREAD: 407 lp->lwp_priority = PRIBASE_THREAD + lp->lwp_rtprio.prio; 408 return; 409 } 410 411 /* 412 * td_upri has normal sense (higher numbers are more desireable), 413 * so negate it. 414 */ 415 lp->lwp_thread->td_upri = -lp->lwp_priority; 416 /* XXX spinlock usually needed */ 417 } 418 419 420 /* 421 * DUMMY_FORKING 422 * 423 * Called from fork1() when a new child process is being created. Allows 424 * the scheduler to predispose the child process before it gets scheduled. 425 * 426 * MPSAFE 427 */ 428 static void 429 dummy_forking(struct lwp *plp, struct lwp *lp) 430 { 431 lp->lwp_estcpu = plp->lwp_estcpu; 432 #if 0 433 ++plp->lwp_estcpu; 434 #endif 435 } 436 437 /* 438 * Called when a lwp is being removed from this scheduler, typically 439 * during lwp_exit(). 440 */ 441 static void 442 dummy_exiting(struct lwp *plp, struct proc *child) 443 { 444 } 445 446 static void 447 dummy_uload_update(struct lwp *lp) 448 { 449 } 450 451 /* 452 * SMP systems may need a scheduler helper thread. This is how one can be 453 * setup. 454 * 455 * We use a neat LWKT scheduling trick to interlock the helper thread. It 456 * is possible to deschedule an LWKT thread and then do some work before 457 * switching away. The thread can be rescheduled at any time, even before 458 * we switch away. 459 * 460 * MPSAFE 461 */ 462 #ifdef SMP 463 464 static void 465 dummy_sched_thread(void *dummy) 466 { 467 globaldata_t gd; 468 dummy_pcpu_t dd; 469 struct lwp *lp; 470 cpumask_t cpumask; 471 cpumask_t tmpmask; 472 int cpuid; 473 int tmpid; 474 475 gd = mycpu; 476 cpuid = gd->gd_cpuid; 477 dd = &dummy_pcpu[cpuid]; 478 cpumask = CPUMASK(cpuid); 479 480 for (;;) { 481 lwkt_deschedule_self(gd->gd_curthread); /* interlock */ 482 atomic_set_cpumask(&dummy_rdyprocmask, cpumask); 483 spin_lock(&dummy_spin); 484 if (dd->uschedcp) { 485 /* 486 * We raced another cpu trying to schedule a thread onto us. 487 * If the runq isn't empty hit another free cpu. 488 */ 489 tmpmask = ~dummy_curprocmask & dummy_rdyprocmask & 490 gd->gd_other_cpus; 491 if (tmpmask && dummy_runqcount) { 492 tmpid = BSFCPUMASK(tmpmask); 493 KKASSERT(tmpid != cpuid); 494 atomic_clear_cpumask(&dummy_rdyprocmask, CPUMASK(tmpid)); 495 spin_unlock(&dummy_spin); 496 lwkt_schedule(&dummy_pcpu[tmpid].helper_thread); 497 } else { 498 spin_unlock(&dummy_spin); 499 } 500 } else if ((lp = TAILQ_FIRST(&dummy_runq)) != NULL) { 501 --dummy_runqcount; 502 TAILQ_REMOVE(&dummy_runq, lp, lwp_procq); 503 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_ONRUNQ); 504 dd->uschedcp = lp; 505 atomic_set_cpumask(&dummy_curprocmask, cpumask); 506 spin_unlock(&dummy_spin); 507 #ifdef SMP 508 lwkt_acquire(lp->lwp_thread); 509 #endif 510 lwkt_schedule(lp->lwp_thread); 511 } else { 512 spin_unlock(&dummy_spin); 513 } 514 lwkt_switch(); 515 } 516 } 517 518 /* 519 * Setup our scheduler helpers. Note that curprocmask bit 0 has already 520 * been cleared by rqinit() and we should not mess with it further. 521 */ 522 static void 523 dummy_sched_thread_cpu_init(void) 524 { 525 int i; 526 527 if (bootverbose) 528 kprintf("start dummy scheduler helpers on cpus:"); 529 530 for (i = 0; i < ncpus; ++i) { 531 dummy_pcpu_t dd = &dummy_pcpu[i]; 532 cpumask_t mask = CPUMASK(i); 533 534 if ((mask & smp_active_mask) == 0) 535 continue; 536 537 if (bootverbose) 538 kprintf(" %d", i); 539 540 lwkt_create(dummy_sched_thread, NULL, NULL, &dd->helper_thread, 541 TDF_NOSTART, i, "dsched %d", i); 542 543 /* 544 * Allow user scheduling on the target cpu. cpu #0 has already 545 * been enabled in rqinit(). 546 */ 547 if (i) 548 atomic_clear_cpumask(&dummy_curprocmask, mask); 549 atomic_set_cpumask(&dummy_rdyprocmask, mask); 550 } 551 if (bootverbose) 552 kprintf("\n"); 553 } 554 SYSINIT(uschedtd, SI_BOOT2_USCHED, SI_ORDER_SECOND, 555 dummy_sched_thread_cpu_init, NULL) 556 557 #endif 558 559