kern_switch.c revision 132543
1/* 2 * Copyright (c) 2001 Jake Burkholder <jake@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27/*** 28Here is the logic.. 29 30If there are N processors, then there are at most N KSEs (kernel 31schedulable entities) working to process threads that belong to a 32KSEGROUP (kg). If there are X of these KSEs actually running at the 33moment in question, then there are at most M (N-X) of these KSEs on 34the run queue, as running KSEs are not on the queue. 35 36Runnable threads are queued off the KSEGROUP in priority order. 37If there are M or more threads runnable, the top M threads 38(by priority) are 'preassigned' to the M KSEs not running. The KSEs take 39their priority from those threads and are put on the run queue. 40 41The last thread that had a priority high enough to have a KSE associated 42with it, AND IS ON THE RUN QUEUE is pointed to by 43kg->kg_last_assigned. If no threads queued off the KSEGROUP have KSEs 44assigned as all the available KSEs are activly running, or because there 45are no threads queued, that pointer is NULL. 46 47When a KSE is removed from the run queue to become runnable, we know 48it was associated with the highest priority thread in the queue (at the head 49of the queue). If it is also the last assigned we know M was 1 and must 50now be 0. Since the thread is no longer queued that pointer must be 51removed from it. Since we know there were no more KSEs available, 52(M was 1 and is now 0) and since we are not FREEING our KSE 53but using it, we know there are STILL no more KSEs available, we can prove 54that the next thread in the ksegrp list will not have a KSE to assign to 55it, so we can show that the pointer must be made 'invalid' (NULL). 56 57The pointer exists so that when a new thread is made runnable, it can 58have its priority compared with the last assigned thread to see if 59it should 'steal' its KSE or not.. i.e. is it 'earlier' 60on the list than that thread or later.. If it's earlier, then the KSE is 61removed from the last assigned (which is now not assigned a KSE) 62and reassigned to the new thread, which is placed earlier in the list. 63The pointer is then backed up to the previous thread (which may or may not 64be the new thread). 65 66When a thread sleeps or is removed, the KSE becomes available and if there 67are queued threads that are not assigned KSEs, the highest priority one of 68them is assigned the KSE, which is then placed back on the run queue at 69the approipriate place, and the kg->kg_last_assigned pointer is adjusted down 70to point to it. 71 72The following diagram shows 2 KSEs and 3 threads from a single process. 73 74 RUNQ: --->KSE---KSE--... (KSEs queued at priorities from threads) 75 \ \____ 76 \ \ 77 KSEGROUP---thread--thread--thread (queued in priority order) 78 \ / 79 \_______________/ 80 (last_assigned) 81 82The result of this scheme is that the M available KSEs are always 83queued at the priorities they have inherrited from the M highest priority 84threads for that KSEGROUP. If this situation changes, the KSEs are 85reassigned to keep this true. 86***/ 87 88#include <sys/cdefs.h> 89__FBSDID("$FreeBSD: head/sys/kern/kern_switch.c 132543 2004-07-22 14:32:48Z scottl $"); 90 91#include "opt_full_preemption.h" 92 93#include <sys/param.h> 94#include <sys/systm.h> 95#include <sys/kdb.h> 96#include <sys/kernel.h> 97#include <sys/ktr.h> 98#include <sys/lock.h> 99#include <sys/mutex.h> 100#include <sys/proc.h> 101#include <sys/queue.h> 102#include <sys/sched.h> 103#if defined(SMP) && (defined(__i386__) || defined(__amd64__)) 104#include <sys/smp.h> 105#endif 106#include <machine/critical.h> 107 108CTASSERT((RQB_BPW * RQB_LEN) == RQ_NQS); 109 110void panc(char *string1, char *string2); 111 112#if 0 113static void runq_readjust(struct runq *rq, struct kse *ke); 114#endif 115/************************************************************************ 116 * Functions that manipulate runnability from a thread perspective. * 117 ************************************************************************/ 118/* 119 * Select the KSE that will be run next. From that find the thread, and 120 * remove it from the KSEGRP's run queue. If there is thread clustering, 121 * this will be what does it. 122 */ 123struct thread * 124choosethread(void) 125{ 126 struct kse *ke; 127 struct thread *td; 128 struct ksegrp *kg; 129 130#if defined(SMP) && (defined(__i386__) || defined(__amd64__)) 131 if (smp_active == 0 && PCPU_GET(cpuid) != 0) { 132 /* Shutting down, run idlethread on AP's */ 133 td = PCPU_GET(idlethread); 134 ke = td->td_kse; 135 CTR1(KTR_RUNQ, "choosethread: td=%p (idle)", td); 136 ke->ke_flags |= KEF_DIDRUN; 137 TD_SET_RUNNING(td); 138 return (td); 139 } 140#endif 141 142retry: 143 ke = sched_choose(); 144 if (ke) { 145 td = ke->ke_thread; 146 KASSERT((td->td_kse == ke), ("kse/thread mismatch")); 147 kg = ke->ke_ksegrp; 148 if (td->td_proc->p_flag & P_SA) { 149 if (kg->kg_last_assigned == td) { 150 kg->kg_last_assigned = TAILQ_PREV(td, 151 threadqueue, td_runq); 152 } 153 TAILQ_REMOVE(&kg->kg_runq, td, td_runq); 154 } 155 kg->kg_runnable--; 156 CTR2(KTR_RUNQ, "choosethread: td=%p pri=%d", 157 td, td->td_priority); 158 } else { 159 /* Simulate runq_choose() having returned the idle thread */ 160 td = PCPU_GET(idlethread); 161 ke = td->td_kse; 162 CTR1(KTR_RUNQ, "choosethread: td=%p (idle)", td); 163 } 164 ke->ke_flags |= KEF_DIDRUN; 165 166 /* 167 * If we are in panic, only allow system threads, 168 * plus the one we are running in, to be run. 169 */ 170 if (panicstr && ((td->td_proc->p_flag & P_SYSTEM) == 0 && 171 (td->td_flags & TDF_INPANIC) == 0)) { 172 /* note that it is no longer on the run queue */ 173 TD_SET_CAN_RUN(td); 174 goto retry; 175 } 176 177 TD_SET_RUNNING(td); 178 return (td); 179} 180 181/* 182 * Given a surplus KSE, either assign a new runable thread to it 183 * (and put it in the run queue) or put it in the ksegrp's idle KSE list. 184 * Assumes that the original thread is not runnable. 185 */ 186void 187kse_reassign(struct kse *ke) 188{ 189 struct ksegrp *kg; 190 struct thread *td; 191 struct thread *original; 192 193 mtx_assert(&sched_lock, MA_OWNED); 194 original = ke->ke_thread; 195 KASSERT(original == NULL || TD_IS_INHIBITED(original), 196 ("reassigning KSE with runnable thread")); 197 kg = ke->ke_ksegrp; 198 if (original) 199 original->td_kse = NULL; 200 201 /* 202 * Find the first unassigned thread 203 */ 204 if ((td = kg->kg_last_assigned) != NULL) 205 td = TAILQ_NEXT(td, td_runq); 206 else 207 td = TAILQ_FIRST(&kg->kg_runq); 208 209 /* 210 * If we found one, assign it the kse, otherwise idle the kse. 211 */ 212 if (td) { 213 kg->kg_last_assigned = td; 214 td->td_kse = ke; 215 ke->ke_thread = td; 216 sched_add(td); 217 CTR2(KTR_RUNQ, "kse_reassign: ke%p -> td%p", ke, td); 218 return; 219 } 220 221 ke->ke_state = KES_IDLE; 222 ke->ke_thread = NULL; 223 TAILQ_INSERT_TAIL(&kg->kg_iq, ke, ke_kgrlist); 224 kg->kg_idle_kses++; 225 CTR1(KTR_RUNQ, "kse_reassign: ke%p on idle queue", ke); 226 return; 227} 228 229#if 0 230/* 231 * Remove a thread from its KSEGRP's run queue. 232 * This in turn may remove it from a KSE if it was already assigned 233 * to one, possibly causing a new thread to be assigned to the KSE 234 * and the KSE getting a new priority. 235 */ 236static void 237remrunqueue(struct thread *td) 238{ 239 struct thread *td2, *td3; 240 struct ksegrp *kg; 241 struct kse *ke; 242 243 mtx_assert(&sched_lock, MA_OWNED); 244 KASSERT((TD_ON_RUNQ(td)), ("remrunqueue: Bad state on run queue")); 245 kg = td->td_ksegrp; 246 ke = td->td_kse; 247 CTR1(KTR_RUNQ, "remrunqueue: td%p", td); 248 kg->kg_runnable--; 249 TD_SET_CAN_RUN(td); 250 /* 251 * If it is not a threaded process, take the shortcut. 252 */ 253 if ((td->td_proc->p_flag & P_SA) == 0) { 254 /* Bring its kse with it, leave the thread attached */ 255 sched_rem(td); 256 ke->ke_state = KES_THREAD; 257 return; 258 } 259 td3 = TAILQ_PREV(td, threadqueue, td_runq); 260 TAILQ_REMOVE(&kg->kg_runq, td, td_runq); 261 if (ke) { 262 /* 263 * This thread has been assigned to a KSE. 264 * We need to dissociate it and try assign the 265 * KSE to the next available thread. Then, we should 266 * see if we need to move the KSE in the run queues. 267 */ 268 sched_rem(td); 269 ke->ke_state = KES_THREAD; 270 td2 = kg->kg_last_assigned; 271 KASSERT((td2 != NULL), ("last assigned has wrong value")); 272 if (td2 == td) 273 kg->kg_last_assigned = td3; 274 kse_reassign(ke); 275 } 276} 277#endif 278 279/* 280 * Change the priority of a thread that is on the run queue. 281 */ 282void 283adjustrunqueue( struct thread *td, int newpri) 284{ 285 struct ksegrp *kg; 286 struct kse *ke; 287 288 mtx_assert(&sched_lock, MA_OWNED); 289 KASSERT((TD_ON_RUNQ(td)), ("adjustrunqueue: Bad state on run queue")); 290 291 ke = td->td_kse; 292 CTR1(KTR_RUNQ, "adjustrunqueue: td%p", td); 293 /* 294 * If it is not a threaded process, take the shortcut. 295 */ 296 if ((td->td_proc->p_flag & P_SA) == 0) { 297 /* We only care about the kse in the run queue. */ 298 td->td_priority = newpri; 299 if (ke->ke_rqindex != (newpri / RQ_PPQ)) { 300 sched_rem(td); 301 sched_add(td); 302 } 303 return; 304 } 305 306 /* It is a threaded process */ 307 kg = td->td_ksegrp; 308 kg->kg_runnable--; 309 TD_SET_CAN_RUN(td); 310 if (ke) { 311 if (kg->kg_last_assigned == td) { 312 kg->kg_last_assigned = 313 TAILQ_PREV(td, threadqueue, td_runq); 314 } 315 sched_rem(td); 316 } 317 TAILQ_REMOVE(&kg->kg_runq, td, td_runq); 318 td->td_priority = newpri; 319 setrunqueue(td); 320} 321 322void 323setrunqueue(struct thread *td) 324{ 325 struct kse *ke; 326 struct ksegrp *kg; 327 struct thread *td2; 328 struct thread *tda; 329 330 CTR1(KTR_RUNQ, "setrunqueue: td%p", td); 331 mtx_assert(&sched_lock, MA_OWNED); 332 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)), 333 ("setrunqueue: bad thread state")); 334 TD_SET_RUNQ(td); 335 kg = td->td_ksegrp; 336 kg->kg_runnable++; 337 if ((td->td_proc->p_flag & P_SA) == 0) { 338 /* 339 * Common path optimisation: Only one of everything 340 * and the KSE is always already attached. 341 * Totally ignore the ksegrp run queue. 342 */ 343 sched_add(td); 344 return; 345 } 346 347 tda = kg->kg_last_assigned; 348 if ((ke = td->td_kse) == NULL) { 349 if (kg->kg_idle_kses) { 350 /* 351 * There is a free one so it's ours for the asking.. 352 */ 353 ke = TAILQ_FIRST(&kg->kg_iq); 354 TAILQ_REMOVE(&kg->kg_iq, ke, ke_kgrlist); 355 ke->ke_state = KES_THREAD; 356 kg->kg_idle_kses--; 357 } else if (tda && (tda->td_priority > td->td_priority)) { 358 /* 359 * None free, but there is one we can commandeer. 360 */ 361 ke = tda->td_kse; 362 sched_rem(tda); 363 tda->td_kse = NULL; 364 ke->ke_thread = NULL; 365 tda = kg->kg_last_assigned = 366 TAILQ_PREV(tda, threadqueue, td_runq); 367 } 368 } else { 369 /* 370 * Temporarily disassociate so it looks like the other cases. 371 */ 372 ke->ke_thread = NULL; 373 td->td_kse = NULL; 374 } 375 376 /* 377 * Add the thread to the ksegrp's run queue at 378 * the appropriate place. 379 */ 380 TAILQ_FOREACH(td2, &kg->kg_runq, td_runq) { 381 if (td2->td_priority > td->td_priority) { 382 TAILQ_INSERT_BEFORE(td2, td, td_runq); 383 break; 384 } 385 } 386 if (td2 == NULL) { 387 /* We ran off the end of the TAILQ or it was empty. */ 388 TAILQ_INSERT_TAIL(&kg->kg_runq, td, td_runq); 389 } 390 391 /* 392 * If we have a ke to use, then put it on the run queue and 393 * If needed, readjust the last_assigned pointer. 394 */ 395 if (ke) { 396 if (tda == NULL) { 397 /* 398 * No pre-existing last assigned so whoever is first 399 * gets the KSE we brought in.. (maybe us) 400 */ 401 td2 = TAILQ_FIRST(&kg->kg_runq); 402 KASSERT((td2->td_kse == NULL), 403 ("unexpected ke present")); 404 td2->td_kse = ke; 405 ke->ke_thread = td2; 406 kg->kg_last_assigned = td2; 407 } else if (tda->td_priority > td->td_priority) { 408 /* 409 * It's ours, grab it, but last_assigned is past us 410 * so don't change it. 411 */ 412 td->td_kse = ke; 413 ke->ke_thread = td; 414 } else { 415 /* 416 * We are past last_assigned, so 417 * put the new kse on whatever is next, 418 * which may or may not be us. 419 */ 420 td2 = TAILQ_NEXT(tda, td_runq); 421 kg->kg_last_assigned = td2; 422 td2->td_kse = ke; 423 ke->ke_thread = td2; 424 } 425 sched_add(ke->ke_thread); 426 } 427} 428 429/* 430 * Kernel thread preemption implementation. Critical sections mark 431 * regions of code in which preemptions are not allowed. 432 */ 433void 434critical_enter(void) 435{ 436 struct thread *td; 437 438 td = curthread; 439 if (td->td_critnest == 0) 440 cpu_critical_enter(); 441 td->td_critnest++; 442} 443 444void 445critical_exit(void) 446{ 447 struct thread *td; 448 449 td = curthread; 450 KASSERT(td->td_critnest != 0, 451 ("critical_exit: td_critnest == 0")); 452 if (td->td_critnest == 1) { 453#if 0 454#ifdef PREEMPTION 455 mtx_assert(&sched_lock, MA_NOTOWNED); 456 if (td->td_pflags & TDP_OWEPREEMPT) { 457 mtx_lock_spin(&sched_lock); 458 mi_switch(SW_INVOL, NULL); 459 mtx_unlock_spin(&sched_lock); 460 } 461#endif 462#endif 463 td->td_critnest = 0; 464 cpu_critical_exit(); 465 } else { 466 td->td_critnest--; 467 } 468} 469 470/* 471 * This function is called when a thread is about to be put on run queue 472 * because it has been made runnable or its priority has been adjusted. It 473 * determines if the new thread should be immediately preempted to. If so, 474 * it switches to it and eventually returns true. If not, it returns false 475 * so that the caller may place the thread on an appropriate run queue. 476 */ 477int 478maybe_preempt(struct thread *td) 479{ 480#ifdef PREEMPTION 481 struct thread *ctd; 482 int cpri, pri; 483#endif 484 485 mtx_assert(&sched_lock, MA_OWNED); 486#ifdef PREEMPTION 487 /* 488 * The new thread should not preempt the current thread if any of the 489 * following conditions are true: 490 * 491 * - The current thread has a higher (numerically lower) or 492 * equivalent priority. Note that this prevents curthread from 493 * trying to preempt to itself. 494 * - It is too early in the boot for context switches (cold is set). 495 * - The current thread has an inhibitor set or is in the process of 496 * exiting. In this case, the current thread is about to switch 497 * out anyways, so there's no point in preempting. If we did, 498 * the current thread would not be properly resumed as well, so 499 * just avoid that whole landmine. 500 * - If the new thread's priority is not a realtime priority and 501 * the current thread's priority is not an idle priority and 502 * FULL_PREEMPTION is disabled. 503 * 504 * If all of these conditions are false, but the current thread is in 505 * a nested critical section, then we have to defer the preemption 506 * until we exit the critical section. Otherwise, switch immediately 507 * to the new thread. 508 */ 509 ctd = curthread; 510 pri = td->td_priority; 511 cpri = ctd->td_priority; 512 if (pri >= cpri || cold /* || dumping */ || TD_IS_INHIBITED(ctd) || 513 td->td_kse->ke_state != KES_THREAD) 514 return (0); 515#ifndef FULL_PREEMPTION 516 if (!(pri >= PRI_MIN_ITHD && pri <= PRI_MAX_ITHD) && 517 !(cpri >= PRI_MIN_IDLE)) 518 return (0); 519#endif 520 if (ctd->td_critnest > 1) { 521 CTR1(KTR_PROC, "maybe_preempt: in critical section %d", 522 ctd->td_critnest); 523 ctd->td_pflags |= TDP_OWEPREEMPT; 524 return (0); 525 } 526 527 /* 528 * Our thread state says that we are already on a run queue, so 529 * update our state as if we had been dequeued by choosethread(). 530 */ 531 MPASS(TD_ON_RUNQ(td)); 532 TD_SET_RUNNING(td); 533 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td, 534 td->td_proc->p_pid, td->td_proc->p_comm); 535 mi_switch(SW_INVOL, td); 536 return (1); 537#else 538 return (0); 539#endif 540} 541 542#ifndef PREEMPTION 543/* XXX: There should be a non-static version of this. */ 544static void 545printf_caddr_t(void *data) 546{ 547 printf("%s", (char *)data); 548} 549static char preempt_warning[] = 550 "WARNING: Kernel preemption is disabled, expect reduced performance.\n"; 551SYSINIT(preempt_warning, SI_SUB_COPYRIGHT, SI_ORDER_ANY, printf_caddr_t, 552 preempt_warning) 553#endif 554 555/************************************************************************ 556 * SYSTEM RUN QUEUE manipulations and tests * 557 ************************************************************************/ 558/* 559 * Initialize a run structure. 560 */ 561void 562runq_init(struct runq *rq) 563{ 564 int i; 565 566 bzero(rq, sizeof *rq); 567 for (i = 0; i < RQ_NQS; i++) 568 TAILQ_INIT(&rq->rq_queues[i]); 569} 570 571/* 572 * Clear the status bit of the queue corresponding to priority level pri, 573 * indicating that it is empty. 574 */ 575static __inline void 576runq_clrbit(struct runq *rq, int pri) 577{ 578 struct rqbits *rqb; 579 580 rqb = &rq->rq_status; 581 CTR4(KTR_RUNQ, "runq_clrbit: bits=%#x %#x bit=%#x word=%d", 582 rqb->rqb_bits[RQB_WORD(pri)], 583 rqb->rqb_bits[RQB_WORD(pri)] & ~RQB_BIT(pri), 584 RQB_BIT(pri), RQB_WORD(pri)); 585 rqb->rqb_bits[RQB_WORD(pri)] &= ~RQB_BIT(pri); 586} 587 588/* 589 * Find the index of the first non-empty run queue. This is done by 590 * scanning the status bits, a set bit indicates a non-empty queue. 591 */ 592static __inline int 593runq_findbit(struct runq *rq) 594{ 595 struct rqbits *rqb; 596 int pri; 597 int i; 598 599 rqb = &rq->rq_status; 600 for (i = 0; i < RQB_LEN; i++) 601 if (rqb->rqb_bits[i]) { 602 pri = RQB_FFS(rqb->rqb_bits[i]) + (i << RQB_L2BPW); 603 CTR3(KTR_RUNQ, "runq_findbit: bits=%#x i=%d pri=%d", 604 rqb->rqb_bits[i], i, pri); 605 return (pri); 606 } 607 608 return (-1); 609} 610 611/* 612 * Set the status bit of the queue corresponding to priority level pri, 613 * indicating that it is non-empty. 614 */ 615static __inline void 616runq_setbit(struct runq *rq, int pri) 617{ 618 struct rqbits *rqb; 619 620 rqb = &rq->rq_status; 621 CTR4(KTR_RUNQ, "runq_setbit: bits=%#x %#x bit=%#x word=%d", 622 rqb->rqb_bits[RQB_WORD(pri)], 623 rqb->rqb_bits[RQB_WORD(pri)] | RQB_BIT(pri), 624 RQB_BIT(pri), RQB_WORD(pri)); 625 rqb->rqb_bits[RQB_WORD(pri)] |= RQB_BIT(pri); 626} 627 628/* 629 * Add the KSE to the queue specified by its priority, and set the 630 * corresponding status bit. 631 */ 632void 633runq_add(struct runq *rq, struct kse *ke) 634{ 635 struct rqhead *rqh; 636 int pri; 637 638 pri = ke->ke_thread->td_priority / RQ_PPQ; 639 ke->ke_rqindex = pri; 640 runq_setbit(rq, pri); 641 rqh = &rq->rq_queues[pri]; 642 CTR4(KTR_RUNQ, "runq_add: p=%p pri=%d %d rqh=%p", 643 ke->ke_proc, ke->ke_thread->td_priority, pri, rqh); 644 TAILQ_INSERT_TAIL(rqh, ke, ke_procq); 645} 646 647/* 648 * Return true if there are runnable processes of any priority on the run 649 * queue, false otherwise. Has no side effects, does not modify the run 650 * queue structure. 651 */ 652int 653runq_check(struct runq *rq) 654{ 655 struct rqbits *rqb; 656 int i; 657 658 rqb = &rq->rq_status; 659 for (i = 0; i < RQB_LEN; i++) 660 if (rqb->rqb_bits[i]) { 661 CTR2(KTR_RUNQ, "runq_check: bits=%#x i=%d", 662 rqb->rqb_bits[i], i); 663 return (1); 664 } 665 CTR0(KTR_RUNQ, "runq_check: empty"); 666 667 return (0); 668} 669 670/* 671 * Find the highest priority process on the run queue. 672 */ 673struct kse * 674runq_choose(struct runq *rq) 675{ 676 struct rqhead *rqh; 677 struct kse *ke; 678 int pri; 679 680 mtx_assert(&sched_lock, MA_OWNED); 681 while ((pri = runq_findbit(rq)) != -1) { 682 rqh = &rq->rq_queues[pri]; 683 ke = TAILQ_FIRST(rqh); 684 KASSERT(ke != NULL, ("runq_choose: no proc on busy queue")); 685 CTR3(KTR_RUNQ, 686 "runq_choose: pri=%d kse=%p rqh=%p", pri, ke, rqh); 687 return (ke); 688 } 689 CTR1(KTR_RUNQ, "runq_choose: idleproc pri=%d", pri); 690 691 return (NULL); 692} 693 694/* 695 * Remove the KSE from the queue specified by its priority, and clear the 696 * corresponding status bit if the queue becomes empty. 697 * Caller must set ke->ke_state afterwards. 698 */ 699void 700runq_remove(struct runq *rq, struct kse *ke) 701{ 702 struct rqhead *rqh; 703 int pri; 704 705 KASSERT(ke->ke_proc->p_sflag & PS_INMEM, 706 ("runq_remove: process swapped out")); 707 pri = ke->ke_rqindex; 708 rqh = &rq->rq_queues[pri]; 709 CTR4(KTR_RUNQ, "runq_remove: p=%p pri=%d %d rqh=%p", 710 ke, ke->ke_thread->td_priority, pri, rqh); 711 KASSERT(ke != NULL, ("runq_remove: no proc on busy queue")); 712 TAILQ_REMOVE(rqh, ke, ke_procq); 713 if (TAILQ_EMPTY(rqh)) { 714 CTR0(KTR_RUNQ, "runq_remove: empty"); 715 runq_clrbit(rq, pri); 716 } 717} 718 719#if 0 720void 721panc(char *string1, char *string2) 722{ 723 printf("%s", string1); 724 kdb_enter(string2); 725} 726 727void 728thread_sanity_check(struct thread *td, char *string) 729{ 730 struct proc *p; 731 struct ksegrp *kg; 732 struct kse *ke; 733 struct thread *td2 = NULL; 734 unsigned int prevpri; 735 int saw_lastassigned = 0; 736 int unassigned = 0; 737 int assigned = 0; 738 739 p = td->td_proc; 740 kg = td->td_ksegrp; 741 ke = td->td_kse; 742 743 744 if (ke) { 745 if (p != ke->ke_proc) { 746 panc(string, "wrong proc"); 747 } 748 if (ke->ke_thread != td) { 749 panc(string, "wrong thread"); 750 } 751 } 752 753 if ((p->p_flag & P_SA) == 0) { 754 if (ke == NULL) { 755 panc(string, "non KSE thread lost kse"); 756 } 757 } else { 758 prevpri = 0; 759 saw_lastassigned = 0; 760 unassigned = 0; 761 assigned = 0; 762 TAILQ_FOREACH(td2, &kg->kg_runq, td_runq) { 763 if (td2->td_priority < prevpri) { 764 panc(string, "thread runqueue unosorted"); 765 } 766 if ((td2->td_state == TDS_RUNQ) && 767 td2->td_kse && 768 (td2->td_kse->ke_state != KES_ONRUNQ)) { 769 panc(string, "KSE wrong state"); 770 } 771 prevpri = td2->td_priority; 772 if (td2->td_kse) { 773 assigned++; 774 if (unassigned) { 775 panc(string, "unassigned before assigned"); 776 } 777 if (kg->kg_last_assigned == NULL) { 778 panc(string, "lastassigned corrupt"); 779 } 780 if (saw_lastassigned) { 781 panc(string, "last assigned not last"); 782 } 783 if (td2->td_kse->ke_thread != td2) { 784 panc(string, "mismatched kse/thread"); 785 } 786 } else { 787 unassigned++; 788 } 789 if (td2 == kg->kg_last_assigned) { 790 saw_lastassigned = 1; 791 if (td2->td_kse == NULL) { 792 panc(string, "last assigned not assigned"); 793 } 794 } 795 } 796 if (kg->kg_last_assigned && (saw_lastassigned == 0)) { 797 panc(string, "where on earth does lastassigned point?"); 798 } 799#if 0 800 FOREACH_THREAD_IN_GROUP(kg, td2) { 801 if (((td2->td_flags & TDF_UNBOUND) == 0) && 802 (TD_ON_RUNQ(td2))) { 803 assigned++; 804 if (td2->td_kse == NULL) { 805 panc(string, "BOUND thread with no KSE"); 806 } 807 } 808 } 809#endif 810#if 0 811 if ((unassigned + assigned) != kg->kg_runnable) { 812 panc(string, "wrong number in runnable"); 813 } 814#endif 815 } 816 if (assigned == 12345) { 817 printf("%p %p %p %p %p %d, %d", 818 td, td2, ke, kg, p, assigned, saw_lastassigned); 819 } 820} 821#endif 822 823