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