1 /*
2 * Copyright (c) 2006-2021 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 *
28 */
29
30 #include <kern/task.h>
31 #include <libkern/libkern.h>
32 #include <machine/atomic.h>
33 #include <mach/coalition.h>
34 #include <os/log.h>
35 #include <sys/coalition.h>
36 #include <sys/proc.h>
37 #include <sys/proc_internal.h>
38 #include <sys/sysctl.h>
39 #include <sys/kdebug.h>
40 #include <sys/kern_memorystatus.h>
41 #include <vm/vm_protos.h>
42 #include <vm/vm_compressor_xnu.h>
43
44 #include <kern/kern_memorystatus_internal.h>
45
46 /*
47 * All memory pressure policy decisions should live here, and there should be
48 * as little mechanism as possible. This file prioritizes readability.
49 */
50
51 #pragma mark Policy Function Declarations
52
53 #if CONFIG_JETSAM
54 static bool memorystatus_check_aggressive_jetsam_needed(int *jld_idle_kills);
55 #endif /* CONFIG_JETSAM */
56
57 #pragma mark Memorystatus Health Check
58
59 /*
60 * Each subsystem that relies on the memorystatus thread
61 * for resource exhaustion should put a health check in this section.
62 * The memorystatus thread runs all of the health checks
63 * to determine if the system is healthy. If the system is unhealthy
64 * it picks an action based on the system health status. See the
65 * Memorystatus Thread Actions section below.
66 */
67
68
69 #if XNU_TARGET_OS_WATCH
70 #define FREEZE_PREVENT_REFREEZE_OF_LAST_THAWED true
71 #define FREEZE_PREVENT_REFREEZE_OF_LAST_THAWED_TIMEOUT_SECONDS (60 * 15)
72 #else
73 #define FREEZE_PREVENT_REFREEZE_OF_LAST_THAWED false
74 #endif
75 extern pid_t memorystatus_freeze_last_pid_thawed;
76 extern uint64_t memorystatus_freeze_last_pid_thawed_ts;
77
78 static void
memorystatus_health_check(memorystatus_system_health_t * status)79 memorystatus_health_check(memorystatus_system_health_t *status)
80 {
81 memset(status, 0, sizeof(memorystatus_system_health_t));
82 #if CONFIG_JETSAM
83 status->msh_available_pages_below_pressure = memorystatus_avail_pages_below_pressure();
84 status->msh_available_pages_below_critical = memorystatus_avail_pages_below_critical();
85 status->msh_compressor_is_low_on_space = (vm_compressor_low_on_space() == TRUE);
86 status->msh_compressed_pages_nearing_limit = vm_compressor_compressed_pages_nearing_limit();
87 status->msh_compressor_is_thrashing = !memorystatus_swap_all_apps && vm_compressor_is_thrashing();
88 #if CONFIG_PHANTOM_CACHE
89 status->msh_phantom_cache_pressure = os_atomic_load(&memorystatus_phantom_cache_pressure, acquire);
90 #else
91 status->msh_phantom_cache_pressure = false;
92 #endif /* CONFIG_PHANTOM_CACHE */
93 if (!memorystatus_swap_all_apps &&
94 status->msh_phantom_cache_pressure &&
95 !(status->msh_compressor_is_thrashing && status->msh_compressor_is_low_on_space)) {
96 status->msh_filecache_is_thrashing = true;
97 }
98 status->msh_compressor_is_low_on_space = os_atomic_load(&memorystatus_compressor_space_shortage, acquire);
99 status->msh_pageout_starved = os_atomic_load(&memorystatus_pageout_starved, acquire);
100 status->msh_swappable_compressor_segments_over_limit = memorystatus_swap_over_trigger(100);
101 status->msh_swapin_queue_over_limit = memorystatus_swapin_over_trigger();
102 status->msh_swap_low_on_space = vm_swap_low_on_space();
103 status->msh_swap_out_of_space = vm_swap_out_of_space();
104 #endif /* CONFIG_JETSAM */
105 status->msh_zone_map_is_exhausted = os_atomic_load(&memorystatus_zone_map_is_exhausted, relaxed);
106 }
107
108 bool
memorystatus_is_system_healthy(const memorystatus_system_health_t * status)109 memorystatus_is_system_healthy(const memorystatus_system_health_t *status)
110 {
111 #if CONFIG_JETSAM
112 return !(status->msh_available_pages_below_critical ||
113 status->msh_compressor_is_low_on_space ||
114 status->msh_compressor_is_thrashing ||
115 status->msh_filecache_is_thrashing ||
116 status->msh_zone_map_is_exhausted ||
117 status->msh_pageout_starved);
118 #else /* CONFIG_JETSAM */
119 return !status->msh_zone_map_is_exhausted;
120 #endif /* CONFIG_JETSAM */
121 }
122
123
124 #pragma mark Memorystatus Thread Actions
125
126 /*
127 * This section picks the appropriate memorystatus_action & deploys it.
128 */
129
130 /*
131 * Inspects the state of various resources in the system to see if
132 * the system is healthy. If the system is not healthy, picks a
133 * memorystatus_action_t to recover the system.
134 *
135 * Every time the memorystatus thread wakes up it calls into here
136 * to pick an action. It will continue performing memorystatus actions until this
137 * function returns MEMORYSTATUS_KILL_NONE. At that point the thread will block.
138 */
139 memorystatus_action_t
memorystatus_pick_action(jetsam_state_t state,uint32_t * kill_cause,bool highwater_remaining,bool suspended_swappable_apps_remaining,bool swappable_apps_remaining,int * jld_idle_kills)140 memorystatus_pick_action(jetsam_state_t state,
141 uint32_t *kill_cause,
142 bool highwater_remaining,
143 bool suspended_swappable_apps_remaining,
144 bool swappable_apps_remaining,
145 int *jld_idle_kills)
146 {
147 memorystatus_system_health_t status;
148 memorystatus_health_check(&status);
149 memorystatus_log_system_health(&status);
150 bool is_system_healthy = memorystatus_is_system_healthy(&status);
151
152 #if CONFIG_JETSAM
153 if (status.msh_available_pages_below_pressure || !is_system_healthy) {
154 /*
155 * If swap is enabled, first check if we're running low or are out of swap space.
156 */
157 if (memorystatus_swap_all_apps && jetsam_kill_on_low_swap) {
158 if (swappable_apps_remaining && status.msh_swap_out_of_space) {
159 *kill_cause = kMemorystatusKilledLowSwap;
160 return MEMORYSTATUS_KILL_SWAPPABLE;
161 } else if (suspended_swappable_apps_remaining && status.msh_swap_low_on_space) {
162 *kill_cause = kMemorystatusKilledLowSwap;
163 return MEMORYSTATUS_KILL_SUSPENDED_SWAPPABLE;
164 }
165 }
166
167 /*
168 * We're below the pressure level or the system is unhealthy,
169 * regardless of the system health let's check if we should be swapping
170 * and if there are high watermark kills left to do.
171 */
172 if (memorystatus_swap_all_apps) {
173 if (status.msh_swappable_compressor_segments_over_limit && !vm_swapout_thread_running && !os_atomic_load(&vm_swapout_wake_pending, relaxed)) {
174 /*
175 * TODO: The swapper will keep running until it has drained the entire early swapout queue.
176 * That might be overly aggressive & we should look into tuning it.
177 * See rdar://84102304.
178 */
179 return MEMORYSTATUS_WAKE_SWAPPER;
180 } else if (status.msh_swapin_queue_over_limit) {
181 return MEMORYSTATUS_PROCESS_SWAPIN_QUEUE;
182 } else if (status.msh_swappable_compressor_segments_over_limit) {
183 memorystatus_log_info(
184 "memorystatus: Skipping swap wakeup because the swap thread is already running. vm_swapout_thread_running=%d, vm_swapout_wake_pending=%d\n",
185 vm_swapout_thread_running, os_atomic_load(&vm_swapout_wake_pending, relaxed));
186 }
187 }
188
189 if (highwater_remaining) {
190 *kill_cause = kMemorystatusKilledHiwat;
191 memorystatus_log("memorystatus: Looking for highwatermark kills.\n");
192 return MEMORYSTATUS_KILL_HIWATER;
193 }
194 }
195
196 if (is_system_healthy) {
197 *kill_cause = 0;
198 return MEMORYSTATUS_KILL_NONE;
199 }
200
201 /*
202 * At this point the system is unhealthy and there are no
203 * more highwatermark processes to kill.
204 */
205
206 if (!state->limit_to_low_bands) {
207 if (memorystatus_check_aggressive_jetsam_needed(jld_idle_kills)) {
208 memorystatus_log("memorystatus: Starting aggressive jetsam.\n");
209 *kill_cause = kMemorystatusKilledProcThrashing;
210 return MEMORYSTATUS_KILL_AGGRESSIVE;
211 }
212 }
213 /*
214 * The system is unhealthy and we either don't need aggressive jetsam
215 * or are not allowed to deploy it.
216 * Kill in priority order. We'll use LRU within every band except the
217 * FG (which will be sorted by coalition role).
218 */
219 *kill_cause = memorystatus_pick_kill_cause(&status);
220 return MEMORYSTATUS_KILL_TOP_PROCESS;
221 #else /* CONFIG_JETSAM */
222 (void) state;
223 (void) jld_idle_kills;
224 (void) suspended_swappable_apps_remaining;
225 (void) swappable_apps_remaining;
226 /*
227 * Without CONFIG_JETSAM, we only kill if the system is unhealthy.
228 * There is no aggressive jetsam and no
229 * early highwatermark killing.
230 */
231 if (is_system_healthy) {
232 *kill_cause = 0;
233 return MEMORYSTATUS_KILL_NONE;
234 }
235 if (highwater_remaining) {
236 *kill_cause = kMemorystatusKilledHiwat;
237 return MEMORYSTATUS_KILL_HIWATER;
238 } else {
239 *kill_cause = memorystatus_pick_kill_cause(&status);
240 return MEMORYSTATUS_KILL_TOP_PROCESS;
241 }
242 #endif /* CONFIG_JETSAM */
243 }
244
245 #pragma mark Aggressive Jetsam
246 /*
247 * This section defines when we deploy aggressive jetsam.
248 * Aggressive jetsam kills everything up to the jld_priority_band_max band.
249 */
250
251 #if CONFIG_JETSAM
252
253 static bool
254 memorystatus_aggressive_jetsam_needed_sysproc_aging(__unused int jld_eval_aggressive_count, __unused int *jld_idle_kills, __unused int jld_idle_kill_candidates, int *total_candidates);
255
256 /*
257 * kJetsamHighRelaunchCandidatesThreshold defines the percentage of candidates
258 * in the idle & deferred bands that need to be bad candidates in order to trigger
259 * aggressive jetsam.
260 */
261 TUNABLE_DEV_WRITEABLE(unsigned int, kJetsamHighRelaunchCandidatesThreshold, "jetsam_high_relaunch_candidates_threshold_percent", 100);
262 #if DEVELOPMENT || DEBUG
263 SYSCTL_UINT(_kern, OID_AUTO, jetsam_high_relaunch_candidates_threshold_percent, CTLFLAG_RW | CTLFLAG_LOCKED, &kJetsamHighRelaunchCandidatesThreshold, 100, "");
264 #endif /* DEVELOPMENT || DEBUG */
265
266 /* kJetsamMinCandidatesThreshold defines the minimum number of candidates in the
267 * idle/deferred bands to trigger aggressive jetsam. This value basically decides
268 * how much memory the system is ready to hold in the lower bands without triggering
269 * aggressive jetsam. This number should ideally be tuned based on the memory config
270 * of the device.
271 */
272 TUNABLE_DT_DEV_WRITEABLE(unsigned int, kJetsamMinCandidatesThreshold, "/defaults", "kern.jetsam_min_candidates_threshold", "jetsam_min_candidates_threshold", 5, TUNABLE_DT_CHECK_CHOSEN);
273 #if DEVELOPMENT || DEBUG
274 SYSCTL_UINT(_kern, OID_AUTO, jetsam_min_candidates_threshold, CTLFLAG_RW | CTLFLAG_LOCKED, &kJetsamMinCandidatesThreshold, 5, "");
275 #endif /* DEVELOPMENT || DEBUG */
276
277 static bool
memorystatus_check_aggressive_jetsam_needed(int * jld_idle_kills)278 memorystatus_check_aggressive_jetsam_needed(int *jld_idle_kills)
279 {
280 bool aggressive_jetsam_needed = false;
281 int total_candidates = 0;
282 /*
283 * The aggressive jetsam logic looks at the number of times it has been in the
284 * aggressive loop to determine the max priority band it should kill upto. The
285 * static variables below are used to track that property.
286 *
287 * To reset those values, the implementation checks if it has been
288 * memorystatus_jld_eval_period_msecs since the parameters were reset.
289 */
290
291 if (memorystatus_jld_enabled == FALSE) {
292 /* If aggressive jetsam is disabled, nothing to do here */
293 return false;
294 }
295
296 /* Get current timestamp (msecs only) */
297 struct timeval jld_now_tstamp = {0, 0};
298 uint64_t jld_now_msecs = 0;
299 microuptime(&jld_now_tstamp);
300 jld_now_msecs = (jld_now_tstamp.tv_sec * 1000);
301
302 /*
303 * Look at the number of candidates in the idle and deferred band and
304 * how many out of them are marked as high relaunch probability.
305 */
306 aggressive_jetsam_needed = memorystatus_aggressive_jetsam_needed_sysproc_aging(jld_eval_aggressive_count,
307 jld_idle_kills, jld_idle_kill_candidates, &total_candidates);
308
309 /*
310 * It is also possible that the system is down to a very small number of processes in the candidate
311 * bands. In that case, the decisions made by the memorystatus_aggressive_jetsam_needed_* routines
312 * would not be useful. In that case, do not trigger aggressive jetsam.
313 */
314 if (total_candidates < kJetsamMinCandidatesThreshold) {
315 memorystatus_log_debug(
316 "memorystatus: aggressive: [FAILED] Low Candidate "
317 "Count (current: %d, threshold: %d)\n",
318 total_candidates, kJetsamMinCandidatesThreshold);
319 aggressive_jetsam_needed = false;
320 }
321
322 /*
323 * Check if its been really long since the aggressive jetsam evaluation
324 * parameters have been refreshed. This logic also resets the jld_eval_aggressive_count
325 * counter to make sure we reset the aggressive jetsam severity.
326 */
327 if ((total_candidates == 0) ||
328 (jld_now_msecs > (jld_timestamp_msecs + memorystatus_jld_eval_period_msecs))) {
329 jld_timestamp_msecs = jld_now_msecs;
330 jld_idle_kill_candidates = total_candidates;
331 *jld_idle_kills = 0;
332 jld_eval_aggressive_count = 0;
333 }
334
335 return aggressive_jetsam_needed;
336 }
337
338 static bool
memorystatus_aggressive_jetsam_needed_sysproc_aging(__unused int eval_aggressive_count,__unused int * idle_kills,__unused int idle_kill_candidates,int * total_candidates)339 memorystatus_aggressive_jetsam_needed_sysproc_aging(__unused int eval_aggressive_count, __unused int *idle_kills, __unused int idle_kill_candidates, int *total_candidates)
340 {
341 bool aggressive_jetsam_needed = false;
342
343 /*
344 * For the kJetsamAgingPolicySysProcsReclaimedFirst aging policy, we maintain the jetsam
345 * relaunch behavior for all daemons. Also, daemons and apps are aged in deferred bands on
346 * every dirty->clean transition. For this aging policy, the best way to determine if
347 * aggressive jetsam is needed, is to see if the kill candidates are mostly bad candidates.
348 * If yes, then we need to go to higher bands to reclaim memory.
349 */
350 proc_list_lock();
351 /* Get total candidate counts for idle and idle deferred bands */
352 *total_candidates = memstat_bucket[JETSAM_PRIORITY_IDLE].count + memstat_bucket[system_procs_aging_band].count;
353 /* Get counts of bad kill candidates in idle and idle deferred bands */
354 int bad_candidates = memstat_bucket[JETSAM_PRIORITY_IDLE].relaunch_high_count + memstat_bucket[system_procs_aging_band].relaunch_high_count;
355
356 proc_list_unlock();
357
358 /* Check if the number of bad candidates is greater than kJetsamHighRelaunchCandidatesThreshold % */
359 aggressive_jetsam_needed = (((bad_candidates * 100) / *total_candidates) >= kJetsamHighRelaunchCandidatesThreshold);
360
361 /*
362 * Since the new aging policy bases the aggressive jetsam trigger on percentage of
363 * bad candidates, it is prone to being overly aggressive. In order to mitigate that,
364 * make sure the system is really under memory pressure before triggering aggressive
365 * jetsam.
366 */
367 if (memorystatus_available_pages > memorystatus_sysproc_aging_aggr_pages) {
368 aggressive_jetsam_needed = false;
369 }
370
371 #if DEVELOPMENT || DEBUG
372 memorystatus_log_info(
373 "memorystatus: aggressive%d: [%s] Bad Candidate Threshold Check (total: %d, bad: %d, threshold: %d %%); Memory Pressure Check (available_pgs: %llu, threshold_pgs: %llu)\n",
374 eval_aggressive_count, aggressive_jetsam_needed ? "PASSED" : "FAILED", *total_candidates, bad_candidates,
375 kJetsamHighRelaunchCandidatesThreshold, (uint64_t)MEMORYSTATUS_LOG_AVAILABLE_PAGES, (uint64_t)memorystatus_sysproc_aging_aggr_pages);
376 #endif /* DEVELOPMENT || DEBUG */
377 return aggressive_jetsam_needed;
378 }
379
380 #endif /* CONFIG_JETSAM */
381
382 #pragma mark Freezer
383 #if CONFIG_FREEZE
384 /*
385 * Freezer policies
386 */
387
388 /*
389 * These functions determine what is eligible for the freezer
390 * and the order that we consider freezing them
391 */
392
393 /*
394 * Checks if the given process is eligible for the freezer.
395 * Processes can only be frozen if this returns true.
396 */
397 bool
memorystatus_is_process_eligible_for_freeze(proc_t p)398 memorystatus_is_process_eligible_for_freeze(proc_t p)
399 {
400 /*
401 * Called with proc_list_lock held.
402 */
403
404 LCK_MTX_ASSERT(&proc_list_mlock, LCK_MTX_ASSERT_OWNED);
405
406 bool should_freeze = false;
407 uint32_t state = 0, pages = 0;
408 bool first_consideration = true;
409 task_t task;
410
411 state = p->p_memstat_state;
412
413 if (state & (P_MEMSTAT_TERMINATED | P_MEMSTAT_LOCKED | P_MEMSTAT_FREEZE_DISABLED | P_MEMSTAT_FREEZE_IGNORE)) {
414 if (state & P_MEMSTAT_FREEZE_DISABLED) {
415 p->p_memstat_freeze_skip_reason = kMemorystatusFreezeSkipReasonDisabled;
416 }
417 goto out;
418 }
419
420 task = proc_task(p);
421
422 if (isSysProc(p)) {
423 /*
424 * Daemon:- We consider freezing it if:
425 * - it belongs to a coalition and the leader is frozen, and,
426 * - its role in the coalition is XPC service.
427 *
428 * We skip memory size requirements in this case.
429 */
430 int task_role_in_coalition = 0;
431 proc_t leader_proc = memorystatus_get_coalition_leader_and_role(p, &task_role_in_coalition);
432 if (leader_proc == PROC_NULL || leader_proc == p) {
433 /*
434 * Jetsam coalition is leaderless or the leader is not an app.
435 * Either way, don't freeze this proc.
436 */
437 goto out;
438 }
439
440 /* Leader must be frozen */
441 if (!(leader_proc->p_memstat_state & P_MEMSTAT_FROZEN)) {
442 goto out;
443 }
444 /* Only freeze XPC services */
445 if (task_role_in_coalition == COALITION_TASKROLE_XPC) {
446 should_freeze = true;
447 }
448
449 goto out;
450 } else {
451 /*
452 * Application. Only freeze if it's suspended.
453 */
454 if (!(state & P_MEMSTAT_SUSPENDED)) {
455 goto out;
456 }
457 }
458
459 /*
460 * We're interested in tracking what percentage of
461 * eligible apps actually get frozen.
462 * To avoid skewing the metrics towards processes which
463 * are considered more frequently, we only track failures once
464 * per process.
465 */
466 first_consideration = !(state & P_MEMSTAT_FREEZE_CONSIDERED);
467
468 if (first_consideration) {
469 memorystatus_freezer_stats.mfs_process_considered_count++;
470 p->p_memstat_state |= P_MEMSTAT_FREEZE_CONSIDERED;
471 }
472
473 /* Only freeze applications meeting our minimum resident page criteria */
474 memorystatus_get_task_page_counts(proc_task(p), &pages, NULL, NULL);
475 if (pages < memorystatus_freeze_pages_min) {
476 if (first_consideration) {
477 memorystatus_freezer_stats.mfs_error_below_min_pages_count++;
478 }
479 p->p_memstat_freeze_skip_reason = kMemorystatusFreezeSkipReasonBelowMinPages;
480 goto out;
481 }
482
483 /* Don't freeze processes that are already exiting on core. It may have started exiting
484 * after we chose it for freeze, but before we obtained the proc_list_lock.
485 * NB: This is only possible if we're coming in from memorystatus_freeze_process_sync.
486 * memorystatus_freeze_top_process holds the proc_list_lock while it traverses the bands.
487 */
488 if (proc_list_exited(p)) {
489 if (first_consideration) {
490 memorystatus_freezer_stats.mfs_error_other_count++;
491 }
492 p->p_memstat_freeze_skip_reason = kMemorystatusFreezeSkipReasonOther;
493 goto out;
494 }
495
496 if (!memorystatus_freezer_use_ordered_list) {
497 /*
498 * We're not using the ordered list so we need to check
499 * that dasd recommended the process. Note that the ordered list
500 * algorithm only considers processes on the list in the first place
501 * so there's no need to double check here.
502 */
503 if (!memorystatus_freeze_process_is_recommended(p)) {
504 if (first_consideration) {
505 memorystatus_freezer_stats.mfs_error_low_probability_of_use_count++;
506 }
507 p->p_memstat_freeze_skip_reason = kMemorystatusFreezeSkipReasonLowProbOfUse;
508 goto out;
509 }
510 }
511
512 if (!(state & P_MEMSTAT_FROZEN) && p->p_memstat_effectivepriority > memorystatus_freeze_max_candidate_band) {
513 /*
514 * Proc has been elevated by something else.
515 * Don't freeze it.
516 */
517 if (first_consideration) {
518 memorystatus_freezer_stats.mfs_error_elevated_count++;
519 }
520 p->p_memstat_freeze_skip_reason = kMemorystatusFreezeSkipReasonElevated;
521 goto out;
522 }
523
524 should_freeze = true;
525 out:
526 if (should_freeze && !(state & P_MEMSTAT_FROZEN)) {
527 /*
528 * Reset the skip reason. If it's killed before we manage to actually freeze it
529 * we failed to consider it early enough.
530 */
531 p->p_memstat_freeze_skip_reason = kMemorystatusFreezeSkipReasonNone;
532 if (!first_consideration) {
533 /*
534 * We're freezing this for the first time and we previously considered it ineligible.
535 * Bump the considered count so that we track this as 1 failure
536 * and 1 success.
537 */
538 memorystatus_freezer_stats.mfs_process_considered_count++;
539 }
540 }
541 return should_freeze;
542 }
543
544 bool
memorystatus_freeze_proc_is_refreeze_eligible(proc_t p)545 memorystatus_freeze_proc_is_refreeze_eligible(proc_t p)
546 {
547 return (p->p_memstat_state & P_MEMSTAT_REFREEZE_ELIGIBLE) != 0;
548 }
549
550
551 static proc_t
memorystatus_freeze_pick_refreeze_process(proc_t last_p)552 memorystatus_freeze_pick_refreeze_process(proc_t last_p)
553 {
554 proc_t p = PROC_NULL, next_p = PROC_NULL;
555 unsigned int band = (unsigned int) memorystatus_freeze_jetsam_band;
556 if (last_p == PROC_NULL) {
557 next_p = memorystatus_get_first_proc_locked(&band, FALSE);
558 } else {
559 next_p = memorystatus_get_next_proc_locked(&band, last_p, FALSE);
560 }
561 while (next_p) {
562 p = next_p;
563 next_p = memorystatus_get_next_proc_locked(&band, p, FALSE);
564 if ((p->p_memstat_state & P_MEMSTAT_FROZEN) && !memorystatus_freeze_proc_is_refreeze_eligible(p)) {
565 /* Process is already frozen & hasn't been thawed. */
566 continue;
567 }
568 /*
569 * Has to have been frozen once before.
570 */
571 if (!(p->p_memstat_state & P_MEMSTAT_FROZEN)) {
572 continue;
573 }
574
575 /*
576 * Not currently being looked at for something.
577 */
578 if (p->p_memstat_state & P_MEMSTAT_LOCKED) {
579 continue;
580 }
581
582 #if FREEZE_PREVENT_REFREEZE_OF_LAST_THAWED
583 /*
584 * Don't refreeze the last process we just thawed if still within the timeout window
585 */
586 if (p->p_pid == memorystatus_freeze_last_pid_thawed) {
587 uint64_t timeout_delta_abs;
588 nanoseconds_to_absolutetime(FREEZE_PREVENT_REFREEZE_OF_LAST_THAWED_TIMEOUT_SECONDS * NSEC_PER_SEC, &timeout_delta_abs);
589 if (mach_absolute_time() < (memorystatus_freeze_last_pid_thawed_ts + timeout_delta_abs)) {
590 continue;
591 }
592 }
593 #endif
594
595 /*
596 * Found it
597 */
598 return p;
599 }
600 return PROC_NULL;
601 }
602
603 proc_t
memorystatus_freeze_pick_process(struct memorystatus_freeze_list_iterator * iterator)604 memorystatus_freeze_pick_process(struct memorystatus_freeze_list_iterator *iterator)
605 {
606 proc_t p = PROC_NULL, next_p = PROC_NULL;
607 unsigned int band = JETSAM_PRIORITY_IDLE;
608
609 LCK_MTX_ASSERT(&proc_list_mlock, LCK_MTX_ASSERT_OWNED);
610 /*
611 * If the freezer is full, only consider refreezes.
612 */
613 if (iterator->refreeze_only || memorystatus_frozen_count >= memorystatus_frozen_processes_max) {
614 if (!iterator->refreeze_only) {
615 /*
616 * The first time the iterator starts to return refreeze
617 * candidates, we need to reset the last pointer b/c it's pointing into the wrong band.
618 */
619 iterator->last_p = PROC_NULL;
620 iterator->refreeze_only = true;
621 }
622 iterator->last_p = memorystatus_freeze_pick_refreeze_process(iterator->last_p);
623 return iterator->last_p;
624 }
625
626 /*
627 * Search for the next freezer candidate.
628 */
629 if (memorystatus_freezer_use_ordered_list) {
630 while (iterator->global_freeze_list_index < memorystatus_global_freeze_list.mfcl_length) {
631 p = memorystatus_freezer_candidate_list_get_proc(
632 &memorystatus_global_freeze_list,
633 (iterator->global_freeze_list_index)++,
634 &memorystatus_freezer_stats.mfs_freeze_pid_mismatches);
635
636 if (p != PROC_NULL && memorystatus_is_process_eligible_for_freeze(p)) {
637 #if FREEZE_PREVENT_REFREEZE_OF_LAST_THAWED
638 /*
639 * Don't refreeze the last process we just thawed if still within the timeout window
640 */
641 if (p->p_pid == memorystatus_freeze_last_pid_thawed) {
642 uint64_t timeout_delta_abs;
643 nanoseconds_to_absolutetime(FREEZE_PREVENT_REFREEZE_OF_LAST_THAWED_TIMEOUT_SECONDS * NSEC_PER_SEC, &timeout_delta_abs);
644 if (mach_absolute_time() < (memorystatus_freeze_last_pid_thawed_ts + timeout_delta_abs)) {
645 continue;
646 }
647 }
648 #endif
649 iterator->last_p = p;
650 return iterator->last_p;
651 }
652 }
653 } else {
654 if (iterator->last_p == PROC_NULL) {
655 next_p = memorystatus_get_first_proc_locked(&band, FALSE);
656 } else {
657 next_p = memorystatus_get_next_proc_locked(&band, iterator->last_p, FALSE);
658 }
659 while (next_p) {
660 p = next_p;
661 if (memorystatus_is_process_eligible_for_freeze(p)) {
662 iterator->last_p = p;
663 return iterator->last_p;
664 } else {
665 next_p = memorystatus_get_next_proc_locked(&band, p, FALSE);
666 }
667 }
668 }
669
670 /*
671 * Failed to find a new freezer candidate.
672 * Try to re-freeze.
673 */
674 if (memorystatus_refreeze_eligible_count >= memorystatus_min_thaw_refreeze_threshold) {
675 assert(!iterator->refreeze_only);
676 iterator->refreeze_only = true;
677 iterator->last_p = memorystatus_freeze_pick_refreeze_process(PROC_NULL);
678 return iterator->last_p;
679 }
680 return PROC_NULL;
681 }
682
683 /*
684 * memorystatus_pages_update calls this function whenever the number
685 * of available pages changes. It wakes the freezer thread iff the function returns
686 * true. The freezer thread will try to freeze (or refreeze) up to 1 process
687 * before blocking again.
688 *
689 * Note the freezer thread is also woken up by memorystatus_on_inactivity.
690 */
691
692 bool
memorystatus_freeze_thread_should_run()693 memorystatus_freeze_thread_should_run()
694 {
695 /*
696 * No freezer_mutex held here...see why near call-site
697 * within memorystatus_pages_update().
698 */
699
700 if (memorystatus_freeze_enabled == false) {
701 return false;
702 }
703
704 if (memorystatus_available_pages > memorystatus_freeze_threshold) {
705 return false;
706 }
707
708 memorystatus_freezer_stats.mfs_below_threshold_count++;
709
710 if ((memorystatus_frozen_count >= memorystatus_frozen_processes_max)) {
711 /*
712 * Consider this as a skip even if we wake up to refreeze because
713 * we won't freeze any new procs.
714 */
715 memorystatus_freezer_stats.mfs_skipped_full_count++;
716 if (memorystatus_refreeze_eligible_count < memorystatus_min_thaw_refreeze_threshold) {
717 return false;
718 }
719 }
720
721 if (memorystatus_frozen_shared_mb_max && (memorystatus_frozen_shared_mb >= memorystatus_frozen_shared_mb_max)) {
722 memorystatus_freezer_stats.mfs_skipped_shared_mb_high_count++;
723 return false;
724 }
725
726 uint64_t curr_time = mach_absolute_time();
727
728 if (curr_time < memorystatus_freezer_thread_next_run_ts) {
729 return false;
730 }
731
732 return true;
733 }
734
735 size_t
memorystatus_pick_freeze_count_for_wakeup()736 memorystatus_pick_freeze_count_for_wakeup()
737 {
738 size_t num_to_freeze = 0;
739 if (!memorystatus_swap_all_apps) {
740 num_to_freeze = 1;
741 } else {
742 /*
743 * When app swap is enabled, we want the freezer thread to aggressively freeze
744 * all candidates so we clear out space for the fg working set.
745 * But we still cap it to the current size of the candidate bands to avoid
746 * consuming excessive CPU if there's a lot of churn in the candidate band.
747 */
748 proc_list_lock();
749 for (unsigned int band = JETSAM_PRIORITY_IDLE; band <= memorystatus_freeze_max_candidate_band; band++) {
750 num_to_freeze += memstat_bucket[band].count;
751 }
752 proc_list_unlock();
753 }
754
755 return num_to_freeze;
756 }
757
758 #endif /* CONFIG_FREEZE */
759