1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
28 /* All Rights Reserved */
29
30 #include <sys/param.h>
31 #include <sys/types.h>
32 #include <sys/sysmacros.h>
33 #include <sys/systm.h>
34 #include <sys/proc.h>
35 #include <sys/cpuvar.h>
36 #include <sys/var.h>
37 #include <sys/tuneable.h>
38 #include <sys/cmn_err.h>
39 #include <sys/buf.h>
40 #include <sys/disp.h>
41 #include <sys/vmsystm.h>
42 #include <sys/vmparam.h>
43 #include <sys/class.h>
44 #include <sys/vtrace.h>
45 #include <sys/modctl.h>
46 #include <sys/debug.h>
47 #include <sys/sdt.h>
48 #include <sys/procfs.h>
49
50 #include <vm/seg.h>
51 #include <vm/seg_kp.h>
52 #include <vm/as.h>
53 #include <vm/rm.h>
54 #include <vm/seg_kmem.h>
55 #include <sys/callb.h>
56
57 /*
58 * The swapper sleeps on runout when there is no one to swap in.
59 * It sleeps on runin when it could not find space to swap someone
60 * in or after swapping someone in.
61 */
62 char runout;
63 char runin;
64 char wake_sched; /* flag tells clock to wake swapper on next tick */
65 char wake_sched_sec; /* flag tells clock to wake swapper after a second */
66
67 /*
68 * The swapper swaps processes to reduce memory demand and runs
69 * when avefree < desfree. The swapper resorts to SOFTSWAP when
70 * avefree < desfree which results in swapping out all processes
71 * sleeping for more than maxslp seconds. HARDSWAP occurs when the
72 * system is on the verge of thrashing and this results in swapping
73 * out runnable threads or threads sleeping for less than maxslp secs.
74 *
75 * The swapper runs through all the active processes in the system
76 * and invokes the scheduling class specific swapin/swapout routine
77 * for every thread in the process to obtain an effective priority
78 * for the process. A priority of -1 implies that the thread isn't
79 * swappable. This effective priority is used to find the most
80 * eligible process to swapout or swapin.
81 *
82 * NOTE: Threads which have been swapped are not linked on any
83 * queue and their dispatcher lock points at the "swapped_lock".
84 *
85 * Processes containing threads with the TS_DONT_SWAP flag set cannot be
86 * swapped out immediately by the swapper. This is due to the fact that
87 * such threads may be holding locks which may be needed by the swapper
88 * to push its pages out. The TS_SWAPENQ flag is set on such threads
89 * to prevent them running in user mode. When such threads reach a
90 * safe point (i.e., are not holding any locks - CL_TRAPRET), they
91 * queue themseleves onto the swap queue which is processed by the
92 * swapper. This results in reducing memory demand when the system
93 * is desparate for memory as the thread can't run in user mode.
94 *
95 * The swap queue consists of threads, linked via t_link, which are
96 * haven't been swapped, are runnable but not on the run queue. The
97 * swap queue is protected by the "swapped_lock". The dispatcher
98 * lock (t_lockp) of all threads on the swap queue points at the
99 * "swapped_lock". Thus, the entire queue and/or threads on the
100 * queue can be locked by acquiring "swapped_lock".
101 */
102 static kthread_t *tswap_queue;
103 extern disp_lock_t swapped_lock; /* protects swap queue and threads on it */
104
105 int maxslp = 0;
106 pgcnt_t avefree; /* 5 sec moving average of free memory */
107 pgcnt_t avefree30; /* 30 sec moving average of free memory */
108
109 /*
110 * Minimum size used to decide if sufficient memory is available
111 * before a process is swapped in. This is necessary since in most
112 * cases the actual size of a process (p_swrss) being swapped in
113 * is usually 2 pages (kernel stack pages). This is due to the fact
114 * almost all user pages of a process are stolen by pageout before
115 * the swapper decides to swapout it out.
116 */
117 int min_procsize = 12;
118
119 static int swapin(proc_t *);
120 static int swapout(proc_t *, uint_t *, int);
121 static void process_swap_queue();
122
123 #ifdef __sparc
124 extern void lwp_swapin(kthread_t *);
125 #endif /* __sparc */
126
127 /*
128 * Counters to keep track of the number of swapins or swapouts.
129 */
130 uint_t tot_swapped_in, tot_swapped_out;
131 uint_t softswap, hardswap, swapqswap;
132
133 /*
134 * Macro to determine if a process is eligble to be swapped.
135 */
136 #define not_swappable(p) \
137 (((p)->p_flag & SSYS) || (p)->p_stat == SIDL || \
138 (p)->p_stat == SZOMB || (p)->p_as == NULL || \
139 (p)->p_as == &kas)
140
141 /*
142 * Memory scheduler.
143 */
144 void
sched()145 sched()
146 {
147 kthread_id_t t;
148 pri_t proc_pri;
149 pri_t thread_pri;
150 pri_t swapin_pri;
151 int desperate;
152 pgcnt_t needs;
153 int divisor;
154 proc_t *prp;
155 proc_t *swapout_prp;
156 proc_t *swapin_prp;
157 spgcnt_t avail;
158 int chosen_pri;
159 time_t swapout_time;
160 time_t swapin_proc_time;
161 callb_cpr_t cprinfo;
162 kmutex_t swap_cpr_lock;
163
164 mutex_init(&swap_cpr_lock, NULL, MUTEX_DEFAULT, NULL);
165 CALLB_CPR_INIT(&cprinfo, &swap_cpr_lock, callb_generic_cpr, "sched");
166 if (maxslp == 0)
167 maxslp = MAXSLP;
168 loop:
169 needs = 0;
170 desperate = 0;
171
172 swapin_pri = v.v_nglobpris;
173 swapin_prp = NULL;
174 chosen_pri = -1;
175
176 process_swap_queue();
177
178 /*
179 * Set desperate if
180 * 1. At least 2 runnable processes (on average).
181 * 2. Short (5 sec) and longer (30 sec) average is less
182 * than minfree and desfree respectively.
183 * 3. Pagein + pageout rate is excessive.
184 */
185 if (avenrun[0] >= 2 * FSCALE &&
186 (MAX(avefree, avefree30) < desfree) &&
187 (pginrate + pgoutrate > maxpgio || avefree < minfree)) {
188 TRACE_4(TR_FAC_SCHED, TR_DESPERATE,
189 "desp:avefree: %d, avefree30: %d, freemem: %d"
190 " pginrate: %d\n", avefree, avefree30, freemem, pginrate);
191 desperate = 1;
192 goto unload;
193 }
194
195 /*
196 * Search list of processes to swapin and swapout deadwood.
197 */
198 swapin_proc_time = 0;
199 top:
200 mutex_enter(&pidlock);
201 for (prp = practive; prp != NULL; prp = prp->p_next) {
202 if (not_swappable(prp))
203 continue;
204
205 /*
206 * Look at processes with at least one swapped lwp.
207 */
208 if (prp->p_swapcnt) {
209 time_t proc_time;
210
211 /*
212 * Higher priority processes are good candidates
213 * to swapin.
214 */
215 mutex_enter(&prp->p_lock);
216 proc_pri = -1;
217 t = prp->p_tlist;
218 proc_time = 0;
219 do {
220 if (t->t_schedflag & TS_LOAD)
221 continue;
222
223 thread_lock(t);
224 thread_pri = CL_SWAPIN(t, 0);
225 thread_unlock(t);
226
227 if (t->t_stime - proc_time > 0)
228 proc_time = t->t_stime;
229 if (thread_pri > proc_pri)
230 proc_pri = thread_pri;
231 } while ((t = t->t_forw) != prp->p_tlist);
232 mutex_exit(&prp->p_lock);
233
234 if (proc_pri == -1)
235 continue;
236
237 TRACE_3(TR_FAC_SCHED, TR_CHOOSE_SWAPIN,
238 "prp %p epri %d proc_time %d",
239 prp, proc_pri, proc_time);
240
241 /*
242 * Swapin processes with a high effective priority.
243 */
244 if (swapin_prp == NULL || proc_pri > chosen_pri) {
245 swapin_prp = prp;
246 chosen_pri = proc_pri;
247 swapin_pri = proc_pri;
248 swapin_proc_time = proc_time;
249 }
250 } else {
251 /*
252 * No need to soft swap if we have sufficient
253 * memory.
254 */
255 if (avefree > desfree ||
256 avefree < desfree && freemem > desfree)
257 continue;
258
259 /*
260 * Skip processes that are exiting
261 * or whose address spaces are locked.
262 */
263 mutex_enter(&prp->p_lock);
264 if ((prp->p_flag & SEXITING) ||
265 (prp->p_as != NULL && AS_ISPGLCK(prp->p_as))) {
266 mutex_exit(&prp->p_lock);
267 continue;
268 }
269
270 /*
271 * Softswapping to kick out deadwood.
272 */
273 proc_pri = -1;
274 t = prp->p_tlist;
275 do {
276 if ((t->t_schedflag & (TS_SWAPENQ |
277 TS_ON_SWAPQ | TS_LOAD)) != TS_LOAD)
278 continue;
279
280 thread_lock(t);
281 thread_pri = CL_SWAPOUT(t, SOFTSWAP);
282 thread_unlock(t);
283 if (thread_pri > proc_pri)
284 proc_pri = thread_pri;
285 } while ((t = t->t_forw) != prp->p_tlist);
286
287 if (proc_pri != -1) {
288 uint_t swrss;
289
290 mutex_exit(&pidlock);
291
292 TRACE_1(TR_FAC_SCHED, TR_SOFTSWAP,
293 "softswap:prp %p", prp);
294
295 (void) swapout(prp, &swrss, SOFTSWAP);
296 softswap++;
297 prp->p_swrss += swrss;
298 mutex_exit(&prp->p_lock);
299 goto top;
300 }
301 mutex_exit(&prp->p_lock);
302 }
303 }
304 if (swapin_prp != NULL)
305 mutex_enter(&swapin_prp->p_lock);
306 mutex_exit(&pidlock);
307
308 if (swapin_prp == NULL) {
309 TRACE_3(TR_FAC_SCHED, TR_RUNOUT,
310 "schedrunout:runout nswapped: %d, avefree: %ld freemem: %ld",
311 nswapped, avefree, freemem);
312
313 t = curthread;
314 thread_lock(t);
315 runout++;
316 t->t_schedflag |= (TS_ALLSTART & ~TS_CSTART);
317 t->t_whystop = PR_SUSPENDED;
318 t->t_whatstop = SUSPEND_NORMAL;
319 (void) new_mstate(t, LMS_SLEEP);
320 mutex_enter(&swap_cpr_lock);
321 CALLB_CPR_SAFE_BEGIN(&cprinfo);
322 mutex_exit(&swap_cpr_lock);
323 thread_stop(t); /* change state and drop lock */
324 swtch();
325 mutex_enter(&swap_cpr_lock);
326 CALLB_CPR_SAFE_END(&cprinfo, &swap_cpr_lock);
327 mutex_exit(&swap_cpr_lock);
328 goto loop;
329 }
330
331 /*
332 * Decide how deserving this process is to be brought in.
333 * Needs is an estimate of how much core the process will
334 * need. If the process has been out for a while, then we
335 * will bring it in with 1/2 the core needed, otherwise
336 * we are conservative.
337 */
338 divisor = 1;
339 swapout_time = (ddi_get_lbolt() - swapin_proc_time) / hz;
340 if (swapout_time > maxslp / 2)
341 divisor = 2;
342
343 needs = MIN(swapin_prp->p_swrss, lotsfree);
344 needs = MAX(needs, min_procsize);
345 needs = needs / divisor;
346
347 /*
348 * Use freemem, since we want processes to be swapped
349 * in quickly.
350 */
351 avail = freemem - deficit;
352 if (avail > (spgcnt_t)needs) {
353 deficit += needs;
354
355 TRACE_2(TR_FAC_SCHED, TR_SWAPIN_VALUES,
356 "swapin_values: prp %p needs %lu", swapin_prp, needs);
357
358 if (swapin(swapin_prp)) {
359 mutex_exit(&swapin_prp->p_lock);
360 goto loop;
361 }
362 deficit -= MIN(needs, deficit);
363 mutex_exit(&swapin_prp->p_lock);
364 } else {
365 mutex_exit(&swapin_prp->p_lock);
366 /*
367 * If deficit is high, too many processes have been
368 * swapped in so wait a sec before attempting to
369 * swapin more.
370 */
371 if (freemem > needs) {
372 TRACE_2(TR_FAC_SCHED, TR_HIGH_DEFICIT,
373 "deficit: prp %p needs %lu", swapin_prp, needs);
374 goto block;
375 }
376 }
377
378 TRACE_2(TR_FAC_SCHED, TR_UNLOAD,
379 "unload: prp %p needs %lu", swapin_prp, needs);
380
381 unload:
382 /*
383 * Unload all unloadable modules, free all other memory
384 * resources we can find, then look for a thread to hardswap.
385 */
386 modreap();
387 segkp_cache_free();
388
389 swapout_prp = NULL;
390 mutex_enter(&pidlock);
391 for (prp = practive; prp != NULL; prp = prp->p_next) {
392
393 /*
394 * No need to soft swap if we have sufficient
395 * memory.
396 */
397 if (not_swappable(prp))
398 continue;
399
400 if (avefree > minfree ||
401 avefree < minfree && freemem > desfree) {
402 swapout_prp = NULL;
403 break;
404 }
405
406 /*
407 * Skip processes that are exiting
408 * or whose address spaces are locked.
409 */
410 mutex_enter(&prp->p_lock);
411 if ((prp->p_flag & SEXITING) ||
412 (prp->p_as != NULL && AS_ISPGLCK(prp->p_as))) {
413 mutex_exit(&prp->p_lock);
414 continue;
415 }
416
417 proc_pri = -1;
418 t = prp->p_tlist;
419 do {
420 if ((t->t_schedflag & (TS_SWAPENQ |
421 TS_ON_SWAPQ | TS_LOAD)) != TS_LOAD)
422 continue;
423
424 thread_lock(t);
425 thread_pri = CL_SWAPOUT(t, HARDSWAP);
426 thread_unlock(t);
427 if (thread_pri > proc_pri)
428 proc_pri = thread_pri;
429 } while ((t = t->t_forw) != prp->p_tlist);
430
431 mutex_exit(&prp->p_lock);
432 if (proc_pri == -1)
433 continue;
434
435 /*
436 * Swapout processes sleeping with a lower priority
437 * than the one currently being swapped in, if any.
438 */
439 if (swapin_prp == NULL || swapin_pri > proc_pri) {
440 TRACE_2(TR_FAC_SCHED, TR_CHOOSE_SWAPOUT,
441 "hardswap: prp %p needs %lu", prp, needs);
442
443 if (swapout_prp == NULL || proc_pri < chosen_pri) {
444 swapout_prp = prp;
445 chosen_pri = proc_pri;
446 }
447 }
448 }
449
450 /*
451 * Acquire the "p_lock" before dropping "pidlock"
452 * to prevent the proc structure from being freed
453 * if the process exits before swapout completes.
454 */
455 if (swapout_prp != NULL)
456 mutex_enter(&swapout_prp->p_lock);
457 mutex_exit(&pidlock);
458
459 if ((prp = swapout_prp) != NULL) {
460 uint_t swrss = 0;
461 int swapped;
462
463 swapped = swapout(prp, &swrss, HARDSWAP);
464 if (swapped) {
465 /*
466 * If desperate, we want to give the space obtained
467 * by swapping this process out to processes in core,
468 * so we give them a chance by increasing deficit.
469 */
470 prp->p_swrss += swrss;
471 if (desperate)
472 deficit += MIN(prp->p_swrss, lotsfree);
473 hardswap++;
474 }
475 mutex_exit(&swapout_prp->p_lock);
476
477 if (swapped)
478 goto loop;
479 }
480
481 /*
482 * Delay for 1 second and look again later.
483 */
484 TRACE_3(TR_FAC_SCHED, TR_RUNIN,
485 "schedrunin:runin nswapped: %d, avefree: %ld freemem: %ld",
486 nswapped, avefree, freemem);
487
488 block:
489 t = curthread;
490 thread_lock(t);
491 runin++;
492 t->t_schedflag |= (TS_ALLSTART & ~TS_CSTART);
493 t->t_whystop = PR_SUSPENDED;
494 t->t_whatstop = SUSPEND_NORMAL;
495 (void) new_mstate(t, LMS_SLEEP);
496 mutex_enter(&swap_cpr_lock);
497 CALLB_CPR_SAFE_BEGIN(&cprinfo);
498 mutex_exit(&swap_cpr_lock);
499 thread_stop(t); /* change to stop state and drop lock */
500 swtch();
501 mutex_enter(&swap_cpr_lock);
502 CALLB_CPR_SAFE_END(&cprinfo, &swap_cpr_lock);
503 mutex_exit(&swap_cpr_lock);
504 goto loop;
505 }
506
507 /*
508 * Remove the specified thread from the swap queue.
509 */
510 static void
swapdeq(kthread_id_t tp)511 swapdeq(kthread_id_t tp)
512 {
513 kthread_id_t *tpp;
514
515 ASSERT(THREAD_LOCK_HELD(tp));
516 ASSERT(tp->t_schedflag & TS_ON_SWAPQ);
517
518 tpp = &tswap_queue;
519 for (;;) {
520 ASSERT(*tpp != NULL);
521 if (*tpp == tp)
522 break;
523 tpp = &(*tpp)->t_link;
524 }
525 *tpp = tp->t_link;
526 tp->t_schedflag &= ~TS_ON_SWAPQ;
527 }
528
529 /*
530 * Swap in lwps. Returns nonzero on success (i.e., if at least one lwp is
531 * swapped in) and 0 on failure.
532 */
533 static int
swapin(proc_t * pp)534 swapin(proc_t *pp)
535 {
536 kthread_id_t tp;
537 int err;
538 int num_swapped_in = 0;
539 struct cpu *cpup = CPU;
540 pri_t thread_pri;
541
542 ASSERT(MUTEX_HELD(&pp->p_lock));
543 ASSERT(pp->p_swapcnt);
544
545 top:
546 tp = pp->p_tlist;
547 do {
548 /*
549 * Only swapin eligible lwps (specified by the scheduling
550 * class) which are unloaded and ready to run.
551 */
552 thread_lock(tp);
553 thread_pri = CL_SWAPIN(tp, 0);
554 if (thread_pri != -1 && tp->t_state == TS_RUN &&
555 (tp->t_schedflag & TS_LOAD) == 0) {
556 size_t stack_size;
557 pgcnt_t stack_pages;
558
559 ASSERT((tp->t_schedflag & TS_ON_SWAPQ) == 0);
560
561 thread_unlock(tp);
562 /*
563 * Now drop the p_lock since the stack needs
564 * to brought in.
565 */
566 mutex_exit(&pp->p_lock);
567
568 stack_size = swapsize(tp->t_swap);
569 stack_pages = btopr(stack_size);
570
571 /* Kernel probe */
572 DTRACE_SCHED1(swapin__lwp, kthread_t *, tp);
573
574 rw_enter(&kas.a_lock, RW_READER);
575 err = segkp_fault(segkp->s_as->a_hat, segkp,
576 tp->t_swap, stack_size, F_SOFTLOCK, S_OTHER);
577 rw_exit(&kas.a_lock);
578
579 /*
580 * Re-acquire the p_lock.
581 */
582 mutex_enter(&pp->p_lock);
583 if (err) {
584 num_swapped_in = 0;
585 break;
586 } else {
587 #ifdef __sparc
588 lwp_swapin(tp);
589 #endif /* __sparc */
590 CPU_STATS_ADDQ(cpup, vm, swapin, 1);
591 CPU_STATS_ADDQ(cpup, vm, pgswapin,
592 stack_pages);
593
594 pp->p_swapcnt--;
595 pp->p_swrss -= stack_pages;
596
597 thread_lock(tp);
598 tp->t_schedflag |= TS_LOAD;
599 dq_sruninc(tp);
600
601 /* set swapin time */
602 tp->t_stime = ddi_get_lbolt();
603 thread_unlock(tp);
604
605 nswapped--;
606 tot_swapped_in++;
607 num_swapped_in++;
608
609 TRACE_2(TR_FAC_SCHED, TR_SWAPIN,
610 "swapin: pp %p stack_pages %lu",
611 pp, stack_pages);
612 goto top;
613 }
614 }
615 thread_unlock(tp);
616 } while ((tp = tp->t_forw) != pp->p_tlist);
617 return (num_swapped_in);
618 }
619
620 /*
621 * Swap out lwps. Returns nonzero on success (i.e., if at least one lwp is
622 * swapped out) and 0 on failure.
623 */
624 static int
swapout(proc_t * pp,uint_t * swrss,int swapflags)625 swapout(proc_t *pp, uint_t *swrss, int swapflags)
626 {
627 kthread_id_t tp;
628 pgcnt_t ws_pages = 0;
629 int err;
630 int swapped_lwps = 0;
631 struct as *as = pp->p_as;
632 struct cpu *cpup = CPU;
633 pri_t thread_pri;
634
635 ASSERT(MUTEX_HELD(&pp->p_lock));
636
637 if (pp->p_flag & SEXITING)
638 return (0);
639
640 top:
641 tp = pp->p_tlist;
642 do {
643 klwp_t *lwp = ttolwp(tp);
644
645 /*
646 * Swapout eligible lwps (specified by the scheduling
647 * class) which don't have TS_DONT_SWAP set. Set the
648 * "intent to swap" flag (TS_SWAPENQ) on threads
649 * which have TS_DONT_SWAP set so that they can be
650 * swapped if and when they reach a safe point.
651 */
652 thread_lock(tp);
653 thread_pri = CL_SWAPOUT(tp, swapflags);
654 if (thread_pri != -1) {
655 if (tp->t_schedflag & TS_DONT_SWAP) {
656 tp->t_schedflag |= TS_SWAPENQ;
657 tp->t_trapret = 1;
658 aston(tp);
659 } else {
660 pgcnt_t stack_pages;
661 size_t stack_size;
662
663 ASSERT((tp->t_schedflag &
664 (TS_DONT_SWAP | TS_LOAD)) == TS_LOAD);
665
666 if (lock_try(&tp->t_lock)) {
667 /*
668 * Remove thread from the swap_queue.
669 */
670 if (tp->t_schedflag & TS_ON_SWAPQ) {
671 ASSERT(!(tp->t_schedflag &
672 TS_SWAPENQ));
673 swapdeq(tp);
674 } else if (tp->t_state == TS_RUN)
675 dq_srundec(tp);
676
677 tp->t_schedflag &=
678 ~(TS_LOAD | TS_SWAPENQ);
679 lock_clear(&tp->t_lock);
680
681 /*
682 * Set swapout time if the thread isn't
683 * sleeping.
684 */
685 if (tp->t_state != TS_SLEEP)
686 tp->t_stime = ddi_get_lbolt();
687 thread_unlock(tp);
688
689 nswapped++;
690 tot_swapped_out++;
691
692 lwp->lwp_ru.nswap++;
693
694 /*
695 * Now drop the p_lock since the
696 * stack needs to pushed out.
697 */
698 mutex_exit(&pp->p_lock);
699
700 stack_size = swapsize(tp->t_swap);
701 stack_pages = btopr(stack_size);
702 ws_pages += stack_pages;
703
704 /* Kernel probe */
705 DTRACE_SCHED1(swapout__lwp,
706 kthread_t *, tp);
707
708 rw_enter(&kas.a_lock, RW_READER);
709 err = segkp_fault(segkp->s_as->a_hat,
710 segkp, tp->t_swap, stack_size,
711 F_SOFTUNLOCK, S_WRITE);
712 rw_exit(&kas.a_lock);
713
714 if (err) {
715 cmn_err(CE_PANIC,
716 "swapout: segkp_fault "
717 "failed err: %d", err);
718 }
719 CPU_STATS_ADDQ(cpup,
720 vm, pgswapout, stack_pages);
721
722 mutex_enter(&pp->p_lock);
723 pp->p_swapcnt++;
724 swapped_lwps++;
725 goto top;
726 }
727 }
728 }
729 thread_unlock(tp);
730 } while ((tp = tp->t_forw) != pp->p_tlist);
731
732 /*
733 * Unload address space when all lwps are swapped out.
734 */
735 if (pp->p_swapcnt == pp->p_lwpcnt) {
736 size_t as_size = 0;
737
738 /*
739 * Avoid invoking as_swapout() if the process has
740 * no MMU resources since pageout will eventually
741 * steal pages belonging to this address space. This
742 * saves CPU cycles as the number of pages that are
743 * potentially freed or pushed out by the segment
744 * swapout operation is very small.
745 */
746 if (rm_asrss(pp->p_as) != 0)
747 as_size = as_swapout(as);
748
749 CPU_STATS_ADDQ(cpup, vm, pgswapout, btop(as_size));
750 CPU_STATS_ADDQ(cpup, vm, swapout, 1);
751 ws_pages += btop(as_size);
752
753 TRACE_2(TR_FAC_SCHED, TR_SWAPOUT,
754 "swapout: pp %p pages_pushed %lu", pp, ws_pages);
755
756 /* Kernel probe */
757 DTRACE_SCHED1(swapout__process, proc_t *, pp);
758 }
759 *swrss = ws_pages;
760 return (swapped_lwps);
761 }
762
763 void
swapout_lwp(klwp_t * lwp)764 swapout_lwp(klwp_t *lwp)
765 {
766 kthread_id_t tp = curthread;
767
768 ASSERT(curthread == lwptot(lwp));
769
770 /*
771 * Don't insert the thread onto the swap queue if
772 * sufficient memory is available.
773 */
774 if (avefree > desfree || avefree < desfree && freemem > desfree) {
775 thread_lock(tp);
776 tp->t_schedflag &= ~TS_SWAPENQ;
777 thread_unlock(tp);
778 return;
779 }
780
781 /*
782 * Lock the thread, then move it to the swapped queue from the
783 * onproc queue and set its state to be TS_RUN.
784 */
785 thread_lock(tp);
786 ASSERT(tp->t_state == TS_ONPROC);
787 if (tp->t_schedflag & TS_SWAPENQ) {
788 tp->t_schedflag &= ~TS_SWAPENQ;
789
790 /*
791 * Set the state of this thread to be runnable
792 * and move it from the onproc queue to the swap queue.
793 */
794 disp_swapped_enq(tp);
795
796 /*
797 * Insert the thread onto the swap queue.
798 */
799 tp->t_link = tswap_queue;
800 tswap_queue = tp;
801 tp->t_schedflag |= TS_ON_SWAPQ;
802
803 thread_unlock_nopreempt(tp);
804
805 TRACE_1(TR_FAC_SCHED, TR_SWAPOUT_LWP, "swapout_lwp:%x", lwp);
806
807 swtch();
808 } else {
809 thread_unlock(tp);
810 }
811 }
812
813 /*
814 * Swap all threads on the swap queue.
815 */
816 static void
process_swap_queue(void)817 process_swap_queue(void)
818 {
819 kthread_id_t tp;
820 uint_t ws_pages;
821 proc_t *pp;
822 struct cpu *cpup = CPU;
823 klwp_t *lwp;
824 int err;
825
826 if (tswap_queue == NULL)
827 return;
828
829 /*
830 * Acquire the "swapped_lock" which locks the swap queue,
831 * and unload the stacks of all threads on it.
832 */
833 disp_lock_enter(&swapped_lock);
834 while ((tp = tswap_queue) != NULL) {
835 pgcnt_t stack_pages;
836 size_t stack_size;
837
838 tswap_queue = tp->t_link;
839 tp->t_link = NULL;
840
841 /*
842 * Drop the "dispatcher lock" before acquiring "t_lock"
843 * to avoid spinning on it since the thread at the front
844 * of the swap queue could be pinned before giving up
845 * its "t_lock" in resume.
846 */
847 disp_lock_exit(&swapped_lock);
848 lock_set(&tp->t_lock);
849
850 /*
851 * Now, re-acquire the "swapped_lock". Acquiring this lock
852 * results in locking the thread since its dispatcher lock
853 * (t_lockp) is the "swapped_lock".
854 */
855 disp_lock_enter(&swapped_lock);
856 ASSERT(tp->t_state == TS_RUN);
857 ASSERT(tp->t_schedflag & (TS_LOAD | TS_ON_SWAPQ));
858
859 tp->t_schedflag &= ~(TS_LOAD | TS_ON_SWAPQ);
860 tp->t_stime = ddi_get_lbolt(); /* swapout time */
861 disp_lock_exit(&swapped_lock);
862 lock_clear(&tp->t_lock);
863
864 lwp = ttolwp(tp);
865 lwp->lwp_ru.nswap++;
866
867 pp = ttoproc(tp);
868 stack_size = swapsize(tp->t_swap);
869 stack_pages = btopr(stack_size);
870
871 /* Kernel probe */
872 DTRACE_SCHED1(swapout__lwp, kthread_t *, tp);
873
874 rw_enter(&kas.a_lock, RW_READER);
875 err = segkp_fault(segkp->s_as->a_hat, segkp, tp->t_swap,
876 stack_size, F_SOFTUNLOCK, S_WRITE);
877 rw_exit(&kas.a_lock);
878
879 if (err) {
880 cmn_err(CE_PANIC,
881 "process_swap_list: segkp_fault failed err: %d", err);
882 }
883 CPU_STATS_ADDQ(cpup, vm, pgswapout, stack_pages);
884
885 nswapped++;
886 tot_swapped_out++;
887 swapqswap++;
888
889 /*
890 * Don't need p_lock since the swapper is the only
891 * thread which increments/decrements p_swapcnt and p_swrss.
892 */
893 ws_pages = stack_pages;
894 pp->p_swapcnt++;
895
896 TRACE_1(TR_FAC_SCHED, TR_SWAPQ_LWP, "swaplist: pp %p", pp);
897
898 /*
899 * Unload address space when all lwps are swapped out.
900 */
901 if (pp->p_swapcnt == pp->p_lwpcnt) {
902 size_t as_size = 0;
903
904 if (rm_asrss(pp->p_as) != 0)
905 as_size = as_swapout(pp->p_as);
906
907 CPU_STATS_ADDQ(cpup, vm, pgswapout,
908 btop(as_size));
909 CPU_STATS_ADDQ(cpup, vm, swapout, 1);
910
911 ws_pages += btop(as_size);
912
913 TRACE_2(TR_FAC_SCHED, TR_SWAPQ_PROC,
914 "swaplist_proc: pp %p pages_pushed: %lu",
915 pp, ws_pages);
916
917 /* Kernel probe */
918 DTRACE_SCHED1(swapout__process, proc_t *, pp);
919 }
920 pp->p_swrss += ws_pages;
921 disp_lock_enter(&swapped_lock);
922 }
923 disp_lock_exit(&swapped_lock);
924 }
925