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FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_swapout.c
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1 /*- 2 * SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU) 3 * 4 * Copyright (c) 1991 Regents of the University of California. 5 * All rights reserved. 6 * Copyright (c) 1994 John S. Dyson 7 * All rights reserved. 8 * Copyright (c) 1994 David Greenman 9 * All rights reserved. 10 * Copyright (c) 2005 Yahoo! Technologies Norway AS 11 * All rights reserved. 12 * 13 * This code is derived from software contributed to Berkeley by 14 * The Mach Operating System project at Carnegie-Mellon University. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 3. All advertising materials mentioning features or use of this software 25 * must display the following acknowledgement: 26 * This product includes software developed by the University of 27 * California, Berkeley and its contributors. 28 * 4. Neither the name of the University nor the names of its contributors 29 * may be used to endorse or promote products derived from this software 30 * without specific prior written permission. 31 * 32 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 35 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 36 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 42 * SUCH DAMAGE. 43 * 44 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 45 * 46 * 47 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 48 * All rights reserved. 49 * 50 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 51 * 52 * Permission to use, copy, modify and distribute this software and 53 * its documentation is hereby granted, provided that both the copyright 54 * notice and this permission notice appear in all copies of the 55 * software, derivative works or modified versions, and any portions 56 * thereof, and that both notices appear in supporting documentation. 57 * 58 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 59 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 60 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 61 * 62 * Carnegie Mellon requests users of this software to return to 63 * 64 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 65 * School of Computer Science 66 * Carnegie Mellon University 67 * Pittsburgh PA 15213-3890 68 * 69 * any improvements or extensions that they make and grant Carnegie the 70 * rights to redistribute these changes. 71 */ 72 73 #include <sys/cdefs.h> 74 __FBSDID("$FreeBSD$"); 75 76 #include "opt_kstack_pages.h" 77 #include "opt_kstack_max_pages.h" 78 #include "opt_vm.h" 79 80 #include <sys/param.h> 81 #include <sys/systm.h> 82 #include <sys/limits.h> 83 #include <sys/kernel.h> 84 #include <sys/eventhandler.h> 85 #include <sys/lock.h> 86 #include <sys/mutex.h> 87 #include <sys/proc.h> 88 #include <sys/kthread.h> 89 #include <sys/ktr.h> 90 #include <sys/mount.h> 91 #include <sys/racct.h> 92 #include <sys/resourcevar.h> 93 #include <sys/refcount.h> 94 #include <sys/sched.h> 95 #include <sys/sdt.h> 96 #include <sys/signalvar.h> 97 #include <sys/smp.h> 98 #include <sys/time.h> 99 #include <sys/vnode.h> 100 #include <sys/vmmeter.h> 101 #include <sys/rwlock.h> 102 #include <sys/sx.h> 103 #include <sys/sysctl.h> 104 105 #include <vm/vm.h> 106 #include <vm/vm_param.h> 107 #include <vm/vm_kern.h> 108 #include <vm/vm_object.h> 109 #include <vm/vm_page.h> 110 #include <vm/vm_map.h> 111 #include <vm/vm_pageout.h> 112 #include <vm/vm_pager.h> 113 #include <vm/vm_phys.h> 114 #include <vm/swap_pager.h> 115 #include <vm/vm_extern.h> 116 #include <vm/uma.h> 117 118 /* the kernel process "vm_daemon" */ 119 static void vm_daemon(void); 120 static struct proc *vmproc; 121 122 static struct kproc_desc vm_kp = { 123 "vmdaemon", 124 vm_daemon, 125 &vmproc 126 }; 127 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); 128 129 static int vm_swap_enabled = 1; 130 static int vm_swap_idle_enabled = 0; 131 132 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RW, 133 &vm_swap_enabled, 0, 134 "Enable entire process swapout"); 135 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RW, 136 &vm_swap_idle_enabled, 0, 137 "Allow swapout on idle criteria"); 138 139 /* 140 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 141 */ 142 static int swap_idle_threshold1 = 2; 143 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 144 &swap_idle_threshold1, 0, 145 "Guaranteed swapped in time for a process"); 146 147 /* 148 * Swap_idle_threshold2 is the time that a process can be idle before 149 * it will be swapped out, if idle swapping is enabled. 150 */ 151 static int swap_idle_threshold2 = 10; 152 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 153 &swap_idle_threshold2, 0, 154 "Time before a process will be swapped out"); 155 156 static int vm_daemon_timeout = 0; 157 SYSCTL_INT(_vm, OID_AUTO, vmdaemon_timeout, CTLFLAG_RW, 158 &vm_daemon_timeout, 0, 159 "Time between vmdaemon runs"); 160 161 static int vm_pageout_req_swapout; /* XXX */ 162 static int vm_daemon_needed; 163 static struct mtx vm_daemon_mtx; 164 /* Allow for use by vm_pageout before vm_daemon is initialized. */ 165 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 166 167 static int swapped_cnt; 168 static int swap_inprogress; /* Pending swap-ins done outside swapper. */ 169 static int last_swapin; 170 171 static void swapclear(struct proc *); 172 static int swapout(struct proc *); 173 static void vm_swapout_map_deactivate_pages(vm_map_t, long); 174 static void vm_swapout_object_deactivate(pmap_t, vm_object_t, long); 175 static void swapout_procs(int action); 176 static void vm_req_vmdaemon(int req); 177 static void vm_thread_swapout(struct thread *td); 178 179 static void 180 vm_swapout_object_deactivate_page(pmap_t pmap, vm_page_t m, bool unmap) 181 { 182 183 /* 184 * Ignore unreclaimable wired pages. Repeat the check after busying 185 * since a busy holder may wire the page. 186 */ 187 if (vm_page_wired(m) || !vm_page_tryxbusy(m)) 188 return; 189 190 if (vm_page_wired(m) || !pmap_page_exists_quick(pmap, m)) { 191 vm_page_xunbusy(m); 192 return; 193 } 194 if (!pmap_is_referenced(m)) { 195 if (!vm_page_active(m)) 196 (void)vm_page_try_remove_all(m); 197 else if (unmap && vm_page_try_remove_all(m)) 198 vm_page_deactivate(m); 199 } 200 vm_page_xunbusy(m); 201 } 202 203 /* 204 * vm_swapout_object_deactivate 205 * 206 * Deactivate enough pages to satisfy the inactive target 207 * requirements. 208 * 209 * The object and map must be locked. 210 */ 211 static void 212 vm_swapout_object_deactivate(pmap_t pmap, vm_object_t first_object, 213 long desired) 214 { 215 vm_object_t backing_object, object; 216 vm_page_t m; 217 bool unmap; 218 219 VM_OBJECT_ASSERT_LOCKED(first_object); 220 if ((first_object->flags & OBJ_FICTITIOUS) != 0) 221 return; 222 for (object = first_object;; object = backing_object) { 223 if (pmap_resident_count(pmap) <= desired) 224 goto unlock_return; 225 VM_OBJECT_ASSERT_LOCKED(object); 226 if ((object->flags & OBJ_UNMANAGED) != 0 || 227 blockcount_read(&object->paging_in_progress) > 0) 228 goto unlock_return; 229 230 unmap = true; 231 if (object->shadow_count > 1) 232 unmap = false; 233 234 /* 235 * Scan the object's entire memory queue. 236 */ 237 TAILQ_FOREACH(m, &object->memq, listq) { 238 if (pmap_resident_count(pmap) <= desired) 239 goto unlock_return; 240 if (should_yield()) 241 goto unlock_return; 242 vm_swapout_object_deactivate_page(pmap, m, unmap); 243 } 244 if ((backing_object = object->backing_object) == NULL) 245 goto unlock_return; 246 VM_OBJECT_RLOCK(backing_object); 247 if (object != first_object) 248 VM_OBJECT_RUNLOCK(object); 249 } 250 unlock_return: 251 if (object != first_object) 252 VM_OBJECT_RUNLOCK(object); 253 } 254 255 /* 256 * deactivate some number of pages in a map, try to do it fairly, but 257 * that is really hard to do. 258 */ 259 static void 260 vm_swapout_map_deactivate_pages(vm_map_t map, long desired) 261 { 262 vm_map_entry_t tmpe; 263 vm_object_t obj, bigobj; 264 int nothingwired; 265 266 if (!vm_map_trylock_read(map)) 267 return; 268 269 bigobj = NULL; 270 nothingwired = TRUE; 271 272 /* 273 * first, search out the biggest object, and try to free pages from 274 * that. 275 */ 276 VM_MAP_ENTRY_FOREACH(tmpe, map) { 277 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 278 obj = tmpe->object.vm_object; 279 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) { 280 if (obj->shadow_count <= 1 && 281 (bigobj == NULL || 282 bigobj->resident_page_count < 283 obj->resident_page_count)) { 284 if (bigobj != NULL) 285 VM_OBJECT_RUNLOCK(bigobj); 286 bigobj = obj; 287 } else 288 VM_OBJECT_RUNLOCK(obj); 289 } 290 } 291 if (tmpe->wired_count > 0) 292 nothingwired = FALSE; 293 } 294 295 if (bigobj != NULL) { 296 vm_swapout_object_deactivate(map->pmap, bigobj, desired); 297 VM_OBJECT_RUNLOCK(bigobj); 298 } 299 /* 300 * Next, hunt around for other pages to deactivate. We actually 301 * do this search sort of wrong -- .text first is not the best idea. 302 */ 303 VM_MAP_ENTRY_FOREACH(tmpe, map) { 304 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 305 break; 306 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 307 obj = tmpe->object.vm_object; 308 if (obj != NULL) { 309 VM_OBJECT_RLOCK(obj); 310 vm_swapout_object_deactivate(map->pmap, obj, 311 desired); 312 VM_OBJECT_RUNLOCK(obj); 313 } 314 } 315 } 316 317 /* 318 * Remove all mappings if a process is swapped out, this will free page 319 * table pages. 320 */ 321 if (desired == 0 && nothingwired) { 322 pmap_remove(vm_map_pmap(map), vm_map_min(map), 323 vm_map_max(map)); 324 } 325 326 vm_map_unlock_read(map); 327 } 328 329 /* 330 * Swap out requests 331 */ 332 #define VM_SWAP_NORMAL 1 333 #define VM_SWAP_IDLE 2 334 335 void 336 vm_swapout_run(void) 337 { 338 339 if (vm_swap_enabled) 340 vm_req_vmdaemon(VM_SWAP_NORMAL); 341 } 342 343 /* 344 * Idle process swapout -- run once per second when pagedaemons are 345 * reclaiming pages. 346 */ 347 void 348 vm_swapout_run_idle(void) 349 { 350 static long lsec; 351 352 if (!vm_swap_idle_enabled || time_second == lsec) 353 return; 354 vm_req_vmdaemon(VM_SWAP_IDLE); 355 lsec = time_second; 356 } 357 358 static void 359 vm_req_vmdaemon(int req) 360 { 361 static int lastrun = 0; 362 363 mtx_lock(&vm_daemon_mtx); 364 vm_pageout_req_swapout |= req; 365 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 366 wakeup(&vm_daemon_needed); 367 lastrun = ticks; 368 } 369 mtx_unlock(&vm_daemon_mtx); 370 } 371 372 static void 373 vm_daemon(void) 374 { 375 struct rlimit rsslim; 376 struct proc *p; 377 struct thread *td; 378 struct vmspace *vm; 379 int breakout, swapout_flags, tryagain, attempts; 380 #ifdef RACCT 381 uint64_t rsize, ravailable; 382 383 if (racct_enable && vm_daemon_timeout == 0) 384 vm_daemon_timeout = hz; 385 #endif 386 387 while (TRUE) { 388 mtx_lock(&vm_daemon_mtx); 389 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 390 vm_daemon_timeout); 391 swapout_flags = vm_pageout_req_swapout; 392 vm_pageout_req_swapout = 0; 393 mtx_unlock(&vm_daemon_mtx); 394 if (swapout_flags != 0) { 395 /* 396 * Drain the per-CPU page queue batches as a deadlock 397 * avoidance measure. 398 */ 399 if ((swapout_flags & VM_SWAP_NORMAL) != 0) 400 vm_page_pqbatch_drain(); 401 swapout_procs(swapout_flags); 402 } 403 404 /* 405 * scan the processes for exceeding their rlimits or if 406 * process is swapped out -- deactivate pages 407 */ 408 tryagain = 0; 409 attempts = 0; 410 again: 411 attempts++; 412 sx_slock(&allproc_lock); 413 FOREACH_PROC_IN_SYSTEM(p) { 414 vm_pindex_t limit, size; 415 416 /* 417 * if this is a system process or if we have already 418 * looked at this process, skip it. 419 */ 420 PROC_LOCK(p); 421 if (p->p_state != PRS_NORMAL || 422 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 423 PROC_UNLOCK(p); 424 continue; 425 } 426 /* 427 * if the process is in a non-running type state, 428 * don't touch it. 429 */ 430 breakout = 0; 431 FOREACH_THREAD_IN_PROC(p, td) { 432 thread_lock(td); 433 if (!TD_ON_RUNQ(td) && 434 !TD_IS_RUNNING(td) && 435 !TD_IS_SLEEPING(td) && 436 !TD_IS_SUSPENDED(td)) { 437 thread_unlock(td); 438 breakout = 1; 439 break; 440 } 441 thread_unlock(td); 442 } 443 if (breakout) { 444 PROC_UNLOCK(p); 445 continue; 446 } 447 /* 448 * get a limit 449 */ 450 lim_rlimit_proc(p, RLIMIT_RSS, &rsslim); 451 limit = OFF_TO_IDX( 452 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 453 454 /* 455 * let processes that are swapped out really be 456 * swapped out set the limit to nothing (will force a 457 * swap-out.) 458 */ 459 if ((p->p_flag & P_INMEM) == 0) 460 limit = 0; /* XXX */ 461 vm = vmspace_acquire_ref(p); 462 _PHOLD_LITE(p); 463 PROC_UNLOCK(p); 464 if (vm == NULL) { 465 PRELE(p); 466 continue; 467 } 468 sx_sunlock(&allproc_lock); 469 470 size = vmspace_resident_count(vm); 471 if (size >= limit) { 472 vm_swapout_map_deactivate_pages( 473 &vm->vm_map, limit); 474 size = vmspace_resident_count(vm); 475 } 476 #ifdef RACCT 477 if (racct_enable) { 478 rsize = IDX_TO_OFF(size); 479 PROC_LOCK(p); 480 if (p->p_state == PRS_NORMAL) 481 racct_set(p, RACCT_RSS, rsize); 482 ravailable = racct_get_available(p, RACCT_RSS); 483 PROC_UNLOCK(p); 484 if (rsize > ravailable) { 485 /* 486 * Don't be overly aggressive; this 487 * might be an innocent process, 488 * and the limit could've been exceeded 489 * by some memory hog. Don't try 490 * to deactivate more than 1/4th 491 * of process' resident set size. 492 */ 493 if (attempts <= 8) { 494 if (ravailable < rsize - 495 (rsize / 4)) { 496 ravailable = rsize - 497 (rsize / 4); 498 } 499 } 500 vm_swapout_map_deactivate_pages( 501 &vm->vm_map, 502 OFF_TO_IDX(ravailable)); 503 /* Update RSS usage after paging out. */ 504 size = vmspace_resident_count(vm); 505 rsize = IDX_TO_OFF(size); 506 PROC_LOCK(p); 507 if (p->p_state == PRS_NORMAL) 508 racct_set(p, RACCT_RSS, rsize); 509 PROC_UNLOCK(p); 510 if (rsize > ravailable) 511 tryagain = 1; 512 } 513 } 514 #endif 515 vmspace_free(vm); 516 sx_slock(&allproc_lock); 517 PRELE(p); 518 } 519 sx_sunlock(&allproc_lock); 520 if (tryagain != 0 && attempts <= 10) { 521 maybe_yield(); 522 goto again; 523 } 524 } 525 } 526 527 /* 528 * Allow a thread's kernel stack to be paged out. 529 */ 530 static void 531 vm_thread_swapout(struct thread *td) 532 { 533 vm_page_t m; 534 vm_offset_t kaddr; 535 vm_pindex_t pindex; 536 int i, pages; 537 538 cpu_thread_swapout(td); 539 kaddr = td->td_kstack; 540 pages = td->td_kstack_pages; 541 pindex = atop(kaddr - VM_MIN_KERNEL_ADDRESS); 542 pmap_qremove(kaddr, pages); 543 VM_OBJECT_WLOCK(kstack_object); 544 for (i = 0; i < pages; i++) { 545 m = vm_page_lookup(kstack_object, pindex + i); 546 if (m == NULL) 547 panic("vm_thread_swapout: kstack already missing?"); 548 vm_page_dirty(m); 549 vm_page_xunbusy_unchecked(m); 550 vm_page_unwire(m, PQ_LAUNDRY); 551 } 552 VM_OBJECT_WUNLOCK(kstack_object); 553 } 554 555 /* 556 * Bring the kernel stack for a specified thread back in. 557 */ 558 static void 559 vm_thread_swapin(struct thread *td, int oom_alloc) 560 { 561 vm_page_t ma[KSTACK_MAX_PAGES]; 562 vm_offset_t kaddr; 563 int a, count, i, j, pages, rv __diagused; 564 565 kaddr = td->td_kstack; 566 pages = td->td_kstack_pages; 567 vm_thread_stack_back(td->td_domain.dr_policy, kaddr, ma, pages, 568 oom_alloc); 569 for (i = 0; i < pages;) { 570 vm_page_assert_xbusied(ma[i]); 571 if (vm_page_all_valid(ma[i])) { 572 i++; 573 continue; 574 } 575 vm_object_pip_add(kstack_object, 1); 576 for (j = i + 1; j < pages; j++) 577 if (vm_page_all_valid(ma[j])) 578 break; 579 VM_OBJECT_WLOCK(kstack_object); 580 rv = vm_pager_has_page(kstack_object, ma[i]->pindex, NULL, &a); 581 VM_OBJECT_WUNLOCK(kstack_object); 582 KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i])); 583 count = min(a + 1, j - i); 584 rv = vm_pager_get_pages(kstack_object, ma + i, count, NULL, NULL); 585 KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d", 586 __func__, td->td_proc->p_pid)); 587 vm_object_pip_wakeup(kstack_object); 588 i += count; 589 } 590 pmap_qenter(kaddr, ma, pages); 591 cpu_thread_swapin(td); 592 } 593 594 void 595 faultin(struct proc *p) 596 { 597 struct thread *td; 598 int oom_alloc; 599 600 PROC_LOCK_ASSERT(p, MA_OWNED); 601 602 /* 603 * If another process is swapping in this process, 604 * just wait until it finishes. 605 */ 606 if (p->p_flag & P_SWAPPINGIN) { 607 while (p->p_flag & P_SWAPPINGIN) 608 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 609 return; 610 } 611 612 if ((p->p_flag & P_INMEM) == 0) { 613 oom_alloc = (p->p_flag & P_WKILLED) != 0 ? VM_ALLOC_SYSTEM : 614 VM_ALLOC_NORMAL; 615 616 /* 617 * Don't let another thread swap process p out while we are 618 * busy swapping it in. 619 */ 620 ++p->p_lock; 621 p->p_flag |= P_SWAPPINGIN; 622 PROC_UNLOCK(p); 623 sx_xlock(&allproc_lock); 624 MPASS(swapped_cnt > 0); 625 swapped_cnt--; 626 if (curthread != &thread0) 627 swap_inprogress++; 628 sx_xunlock(&allproc_lock); 629 630 /* 631 * We hold no lock here because the list of threads 632 * can not change while all threads in the process are 633 * swapped out. 634 */ 635 FOREACH_THREAD_IN_PROC(p, td) 636 vm_thread_swapin(td, oom_alloc); 637 638 if (curthread != &thread0) { 639 sx_xlock(&allproc_lock); 640 MPASS(swap_inprogress > 0); 641 swap_inprogress--; 642 last_swapin = ticks; 643 sx_xunlock(&allproc_lock); 644 } 645 PROC_LOCK(p); 646 swapclear(p); 647 p->p_swtick = ticks; 648 649 /* Allow other threads to swap p out now. */ 650 wakeup(&p->p_flag); 651 --p->p_lock; 652 } 653 } 654 655 /* 656 * This swapin algorithm attempts to swap-in processes only if there 657 * is enough space for them. Of course, if a process waits for a long 658 * time, it will be swapped in anyway. 659 */ 660 661 static struct proc * 662 swapper_selector(bool wkilled_only) 663 { 664 struct proc *p, *res; 665 struct thread *td; 666 int ppri, pri, slptime, swtime; 667 668 sx_assert(&allproc_lock, SA_SLOCKED); 669 if (swapped_cnt == 0) 670 return (NULL); 671 res = NULL; 672 ppri = INT_MIN; 673 FOREACH_PROC_IN_SYSTEM(p) { 674 PROC_LOCK(p); 675 if (p->p_state == PRS_NEW || (p->p_flag & (P_SWAPPINGOUT | 676 P_SWAPPINGIN | P_INMEM)) != 0) { 677 PROC_UNLOCK(p); 678 continue; 679 } 680 if (p->p_state == PRS_NORMAL && (p->p_flag & P_WKILLED) != 0) { 681 /* 682 * A swapped-out process might have mapped a 683 * large portion of the system's pages as 684 * anonymous memory. There is no other way to 685 * release the memory other than to kill the 686 * process, for which we need to swap it in. 687 */ 688 return (p); 689 } 690 if (wkilled_only) { 691 PROC_UNLOCK(p); 692 continue; 693 } 694 swtime = (ticks - p->p_swtick) / hz; 695 FOREACH_THREAD_IN_PROC(p, td) { 696 /* 697 * An otherwise runnable thread of a process 698 * swapped out has only the TDI_SWAPPED bit set. 699 */ 700 thread_lock(td); 701 if (td->td_inhibitors == TDI_SWAPPED) { 702 slptime = (ticks - td->td_slptick) / hz; 703 pri = swtime + slptime; 704 if ((td->td_flags & TDF_SWAPINREQ) == 0) 705 pri -= p->p_nice * 8; 706 /* 707 * if this thread is higher priority 708 * and there is enough space, then select 709 * this process instead of the previous 710 * selection. 711 */ 712 if (pri > ppri) { 713 res = p; 714 ppri = pri; 715 } 716 } 717 thread_unlock(td); 718 } 719 PROC_UNLOCK(p); 720 } 721 722 if (res != NULL) 723 PROC_LOCK(res); 724 return (res); 725 } 726 727 #define SWAPIN_INTERVAL (MAXSLP * hz / 2) 728 729 /* 730 * Limit swapper to swap in one non-WKILLED process in MAXSLP/2 731 * interval, assuming that there is: 732 * - at least one domain that is not suffering from a shortage of free memory; 733 * - no parallel swap-ins; 734 * - no other swap-ins in the current SWAPIN_INTERVAL. 735 */ 736 static bool 737 swapper_wkilled_only(void) 738 { 739 740 return (vm_page_count_min_set(&all_domains) || swap_inprogress > 0 || 741 (u_int)(ticks - last_swapin) < SWAPIN_INTERVAL); 742 } 743 744 void 745 swapper(void) 746 { 747 struct proc *p; 748 749 for (;;) { 750 sx_slock(&allproc_lock); 751 p = swapper_selector(swapper_wkilled_only()); 752 sx_sunlock(&allproc_lock); 753 754 if (p == NULL) { 755 tsleep(&proc0, PVM, "swapin", SWAPIN_INTERVAL); 756 } else { 757 PROC_LOCK_ASSERT(p, MA_OWNED); 758 759 /* 760 * Another process may be bringing or may have 761 * already brought this process in while we 762 * traverse all threads. Or, this process may 763 * have exited or even being swapped out 764 * again. 765 */ 766 if (p->p_state == PRS_NORMAL && (p->p_flag & (P_INMEM | 767 P_SWAPPINGOUT | P_SWAPPINGIN)) == 0) { 768 faultin(p); 769 } 770 PROC_UNLOCK(p); 771 } 772 } 773 } 774 775 /* 776 * First, if any processes have been sleeping or stopped for at least 777 * "swap_idle_threshold1" seconds, they are swapped out. If, however, 778 * no such processes exist, then the longest-sleeping or stopped 779 * process is swapped out. Finally, and only as a last resort, if 780 * there are no sleeping or stopped processes, the longest-resident 781 * process is swapped out. 782 */ 783 static void 784 swapout_procs(int action) 785 { 786 struct proc *p; 787 struct thread *td; 788 int slptime; 789 bool didswap, doswap; 790 791 MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0); 792 793 didswap = false; 794 sx_slock(&allproc_lock); 795 FOREACH_PROC_IN_SYSTEM(p) { 796 /* 797 * Filter out not yet fully constructed processes. Do 798 * not swap out held processes. Avoid processes which 799 * are system, exiting, execing, traced, already swapped 800 * out or are in the process of being swapped in or out. 801 */ 802 PROC_LOCK(p); 803 if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag & 804 (P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE | 805 P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) != 806 P_INMEM) { 807 PROC_UNLOCK(p); 808 continue; 809 } 810 811 /* 812 * Further consideration of this process for swap out 813 * requires iterating over its threads. We release 814 * allproc_lock here so that process creation and 815 * destruction are not blocked while we iterate. 816 * 817 * To later reacquire allproc_lock and resume 818 * iteration over the allproc list, we will first have 819 * to release the lock on the process. We place a 820 * hold on the process so that it remains in the 821 * allproc list while it is unlocked. 822 */ 823 _PHOLD_LITE(p); 824 sx_sunlock(&allproc_lock); 825 826 /* 827 * Do not swapout a realtime process. 828 * Guarantee swap_idle_threshold1 time in memory. 829 * If the system is under memory stress, or if we are 830 * swapping idle processes >= swap_idle_threshold2, 831 * then swap the process out. 832 */ 833 doswap = true; 834 FOREACH_THREAD_IN_PROC(p, td) { 835 thread_lock(td); 836 slptime = (ticks - td->td_slptick) / hz; 837 if (PRI_IS_REALTIME(td->td_pri_class) || 838 slptime < swap_idle_threshold1 || 839 !thread_safetoswapout(td) || 840 ((action & VM_SWAP_NORMAL) == 0 && 841 slptime < swap_idle_threshold2)) 842 doswap = false; 843 thread_unlock(td); 844 if (!doswap) 845 break; 846 } 847 if (doswap && swapout(p) == 0) 848 didswap = true; 849 850 PROC_UNLOCK(p); 851 if (didswap) { 852 sx_xlock(&allproc_lock); 853 swapped_cnt++; 854 sx_downgrade(&allproc_lock); 855 } else 856 sx_slock(&allproc_lock); 857 PRELE(p); 858 } 859 sx_sunlock(&allproc_lock); 860 861 /* 862 * If we swapped something out, and another process needed memory, 863 * then wakeup the sched process. 864 */ 865 if (didswap) 866 wakeup(&proc0); 867 } 868 869 static void 870 swapclear(struct proc *p) 871 { 872 struct thread *td; 873 874 PROC_LOCK_ASSERT(p, MA_OWNED); 875 876 FOREACH_THREAD_IN_PROC(p, td) { 877 thread_lock(td); 878 td->td_flags |= TDF_INMEM; 879 td->td_flags &= ~TDF_SWAPINREQ; 880 TD_CLR_SWAPPED(td); 881 if (TD_CAN_RUN(td)) { 882 if (setrunnable(td, 0)) { 883 #ifdef INVARIANTS 884 /* 885 * XXX: We just cleared TDI_SWAPPED 886 * above and set TDF_INMEM, so this 887 * should never happen. 888 */ 889 panic("not waking up swapper"); 890 #endif 891 } 892 } else 893 thread_unlock(td); 894 } 895 p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT); 896 p->p_flag |= P_INMEM; 897 } 898 899 static int 900 swapout(struct proc *p) 901 { 902 struct thread *td; 903 904 PROC_LOCK_ASSERT(p, MA_OWNED); 905 906 /* 907 * The states of this process and its threads may have changed 908 * by now. Assuming that there is only one pageout daemon thread, 909 * this process should still be in memory. 910 */ 911 KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) == 912 P_INMEM, ("swapout: lost a swapout race?")); 913 914 /* 915 * Remember the resident count. 916 */ 917 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 918 919 /* 920 * Check and mark all threads before we proceed. 921 */ 922 p->p_flag &= ~P_INMEM; 923 p->p_flag |= P_SWAPPINGOUT; 924 FOREACH_THREAD_IN_PROC(p, td) { 925 thread_lock(td); 926 if (!thread_safetoswapout(td)) { 927 thread_unlock(td); 928 swapclear(p); 929 return (EBUSY); 930 } 931 td->td_flags &= ~TDF_INMEM; 932 TD_SET_SWAPPED(td); 933 thread_unlock(td); 934 } 935 td = FIRST_THREAD_IN_PROC(p); 936 ++td->td_ru.ru_nswap; 937 PROC_UNLOCK(p); 938 939 /* 940 * This list is stable because all threads are now prevented from 941 * running. The list is only modified in the context of a running 942 * thread in this process. 943 */ 944 FOREACH_THREAD_IN_PROC(p, td) 945 vm_thread_swapout(td); 946 947 PROC_LOCK(p); 948 p->p_flag &= ~P_SWAPPINGOUT; 949 p->p_swtick = ticks; 950 return (0); 951 }
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