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_object.h> 108 #include <vm/vm_page.h> 109 #include <vm/vm_map.h> 110 #include <vm/vm_pageout.h> 111 #include <vm/vm_pager.h> 112 #include <vm/vm_phys.h> 113 #include <vm/swap_pager.h> 114 #include <vm/vm_extern.h> 115 #include <vm/uma.h> 116 117 /* the kernel process "vm_daemon" */ 118 static void vm_daemon(void); 119 static struct proc *vmproc; 120 121 static struct kproc_desc vm_kp = { 122 "vmdaemon", 123 vm_daemon, 124 &vmproc 125 }; 126 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); 127 128 static int vm_swap_enabled = 1; 129 static int vm_swap_idle_enabled = 0; 130 131 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RW, 132 &vm_swap_enabled, 0, 133 "Enable entire process swapout"); 134 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RW, 135 &vm_swap_idle_enabled, 0, 136 "Allow swapout on idle criteria"); 137 138 /* 139 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 140 */ 141 static int swap_idle_threshold1 = 2; 142 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 143 &swap_idle_threshold1, 0, 144 "Guaranteed swapped in time for a process"); 145 146 /* 147 * Swap_idle_threshold2 is the time that a process can be idle before 148 * it will be swapped out, if idle swapping is enabled. 149 */ 150 static int swap_idle_threshold2 = 10; 151 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 152 &swap_idle_threshold2, 0, 153 "Time before a process will be swapped out"); 154 155 static int vm_pageout_req_swapout; /* XXX */ 156 static int vm_daemon_needed; 157 static struct mtx vm_daemon_mtx; 158 /* Allow for use by vm_pageout before vm_daemon is initialized. */ 159 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 160 161 static int swapped_cnt; 162 static int swap_inprogress; /* Pending swap-ins done outside swapper. */ 163 static int last_swapin; 164 165 static void swapclear(struct proc *); 166 static int swapout(struct proc *); 167 static void vm_swapout_map_deactivate_pages(vm_map_t, long); 168 static void vm_swapout_object_deactivate_pages(pmap_t, vm_object_t, long); 169 static void swapout_procs(int action); 170 static void vm_req_vmdaemon(int req); 171 static void vm_thread_swapout(struct thread *td); 172 173 /* 174 * vm_swapout_object_deactivate_pages 175 * 176 * Deactivate enough pages to satisfy the inactive target 177 * requirements. 178 * 179 * The object and map must be locked. 180 */ 181 static void 182 vm_swapout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, 183 long desired) 184 { 185 vm_object_t backing_object, object; 186 vm_page_t p; 187 int act_delta, remove_mode; 188 189 VM_OBJECT_ASSERT_LOCKED(first_object); 190 if ((first_object->flags & OBJ_FICTITIOUS) != 0) 191 return; 192 for (object = first_object;; object = backing_object) { 193 if (pmap_resident_count(pmap) <= desired) 194 goto unlock_return; 195 VM_OBJECT_ASSERT_LOCKED(object); 196 if ((object->flags & OBJ_UNMANAGED) != 0 || 197 REFCOUNT_COUNT(object->paging_in_progress) > 0) 198 goto unlock_return; 199 200 remove_mode = 0; 201 if (object->shadow_count > 1) 202 remove_mode = 1; 203 /* 204 * Scan the object's entire memory queue. 205 */ 206 TAILQ_FOREACH(p, &object->memq, listq) { 207 if (pmap_resident_count(pmap) <= desired) 208 goto unlock_return; 209 if (should_yield()) 210 goto unlock_return; 211 212 /* 213 * The page may acquire a wiring after this check. 214 * The page daemon handles wired pages, so there is 215 * no harm done if a wiring appears while we are 216 * attempting to deactivate the page. 217 */ 218 if (vm_page_busied(p) || vm_page_wired(p)) 219 continue; 220 VM_CNT_INC(v_pdpages); 221 if (!pmap_page_exists_quick(pmap, p)) 222 continue; 223 act_delta = pmap_ts_referenced(p); 224 vm_page_lock(p); 225 if ((p->aflags & PGA_REFERENCED) != 0) { 226 if (act_delta == 0) 227 act_delta = 1; 228 vm_page_aflag_clear(p, PGA_REFERENCED); 229 } 230 if (!vm_page_active(p) && act_delta != 0) { 231 vm_page_activate(p); 232 p->act_count += act_delta; 233 } else if (vm_page_active(p)) { 234 /* 235 * The page daemon does not requeue pages 236 * after modifying their activation count. 237 */ 238 if (act_delta == 0) { 239 p->act_count -= min(p->act_count, 240 ACT_DECLINE); 241 if (!remove_mode && p->act_count == 0) { 242 (void)vm_page_try_remove_all(p); 243 vm_page_deactivate(p); 244 } 245 } else { 246 vm_page_activate(p); 247 if (p->act_count < ACT_MAX - 248 ACT_ADVANCE) 249 p->act_count += ACT_ADVANCE; 250 } 251 } else if (vm_page_inactive(p)) 252 (void)vm_page_try_remove_all(p); 253 vm_page_unlock(p); 254 } 255 if ((backing_object = object->backing_object) == NULL) 256 goto unlock_return; 257 VM_OBJECT_RLOCK(backing_object); 258 if (object != first_object) 259 VM_OBJECT_RUNLOCK(object); 260 } 261 unlock_return: 262 if (object != first_object) 263 VM_OBJECT_RUNLOCK(object); 264 } 265 266 /* 267 * deactivate some number of pages in a map, try to do it fairly, but 268 * that is really hard to do. 269 */ 270 static void 271 vm_swapout_map_deactivate_pages(vm_map_t map, long desired) 272 { 273 vm_map_entry_t tmpe; 274 vm_object_t obj, bigobj; 275 int nothingwired; 276 277 if (!vm_map_trylock_read(map)) 278 return; 279 280 bigobj = NULL; 281 nothingwired = TRUE; 282 283 /* 284 * first, search out the biggest object, and try to free pages from 285 * that. 286 */ 287 tmpe = map->header.next; 288 while (tmpe != &map->header) { 289 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 290 obj = tmpe->object.vm_object; 291 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) { 292 if (obj->shadow_count <= 1 && 293 (bigobj == NULL || 294 bigobj->resident_page_count < 295 obj->resident_page_count)) { 296 if (bigobj != NULL) 297 VM_OBJECT_RUNLOCK(bigobj); 298 bigobj = obj; 299 } else 300 VM_OBJECT_RUNLOCK(obj); 301 } 302 } 303 if (tmpe->wired_count > 0) 304 nothingwired = FALSE; 305 tmpe = tmpe->next; 306 } 307 308 if (bigobj != NULL) { 309 vm_swapout_object_deactivate_pages(map->pmap, bigobj, desired); 310 VM_OBJECT_RUNLOCK(bigobj); 311 } 312 /* 313 * Next, hunt around for other pages to deactivate. We actually 314 * do this search sort of wrong -- .text first is not the best idea. 315 */ 316 tmpe = map->header.next; 317 while (tmpe != &map->header) { 318 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 319 break; 320 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 321 obj = tmpe->object.vm_object; 322 if (obj != NULL) { 323 VM_OBJECT_RLOCK(obj); 324 vm_swapout_object_deactivate_pages(map->pmap, 325 obj, desired); 326 VM_OBJECT_RUNLOCK(obj); 327 } 328 } 329 tmpe = tmpe->next; 330 } 331 332 /* 333 * Remove all mappings if a process is swapped out, this will free page 334 * table pages. 335 */ 336 if (desired == 0 && nothingwired) { 337 pmap_remove(vm_map_pmap(map), vm_map_min(map), 338 vm_map_max(map)); 339 } 340 341 vm_map_unlock_read(map); 342 } 343 344 /* 345 * Swap out requests 346 */ 347 #define VM_SWAP_NORMAL 1 348 #define VM_SWAP_IDLE 2 349 350 void 351 vm_swapout_run(void) 352 { 353 354 if (vm_swap_enabled) 355 vm_req_vmdaemon(VM_SWAP_NORMAL); 356 } 357 358 /* 359 * Idle process swapout -- run once per second when pagedaemons are 360 * reclaiming pages. 361 */ 362 void 363 vm_swapout_run_idle(void) 364 { 365 static long lsec; 366 367 if (!vm_swap_idle_enabled || time_second == lsec) 368 return; 369 vm_req_vmdaemon(VM_SWAP_IDLE); 370 lsec = time_second; 371 } 372 373 static void 374 vm_req_vmdaemon(int req) 375 { 376 static int lastrun = 0; 377 378 mtx_lock(&vm_daemon_mtx); 379 vm_pageout_req_swapout |= req; 380 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 381 wakeup(&vm_daemon_needed); 382 lastrun = ticks; 383 } 384 mtx_unlock(&vm_daemon_mtx); 385 } 386 387 static void 388 vm_daemon(void) 389 { 390 struct rlimit rsslim; 391 struct proc *p; 392 struct thread *td; 393 struct vmspace *vm; 394 int breakout, swapout_flags, tryagain, attempts; 395 #ifdef RACCT 396 uint64_t rsize, ravailable; 397 #endif 398 399 while (TRUE) { 400 mtx_lock(&vm_daemon_mtx); 401 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 402 #ifdef RACCT 403 racct_enable ? hz : 0 404 #else 405 0 406 #endif 407 ); 408 swapout_flags = vm_pageout_req_swapout; 409 vm_pageout_req_swapout = 0; 410 mtx_unlock(&vm_daemon_mtx); 411 if (swapout_flags != 0) { 412 /* 413 * Drain the per-CPU page queue batches as a deadlock 414 * avoidance measure. 415 */ 416 if ((swapout_flags & VM_SWAP_NORMAL) != 0) 417 vm_page_pqbatch_drain(); 418 swapout_procs(swapout_flags); 419 } 420 421 /* 422 * scan the processes for exceeding their rlimits or if 423 * process is swapped out -- deactivate pages 424 */ 425 tryagain = 0; 426 attempts = 0; 427 again: 428 attempts++; 429 sx_slock(&allproc_lock); 430 FOREACH_PROC_IN_SYSTEM(p) { 431 vm_pindex_t limit, size; 432 433 /* 434 * if this is a system process or if we have already 435 * looked at this process, skip it. 436 */ 437 PROC_LOCK(p); 438 if (p->p_state != PRS_NORMAL || 439 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 440 PROC_UNLOCK(p); 441 continue; 442 } 443 /* 444 * if the process is in a non-running type state, 445 * don't touch it. 446 */ 447 breakout = 0; 448 FOREACH_THREAD_IN_PROC(p, td) { 449 thread_lock(td); 450 if (!TD_ON_RUNQ(td) && 451 !TD_IS_RUNNING(td) && 452 !TD_IS_SLEEPING(td) && 453 !TD_IS_SUSPENDED(td)) { 454 thread_unlock(td); 455 breakout = 1; 456 break; 457 } 458 thread_unlock(td); 459 } 460 if (breakout) { 461 PROC_UNLOCK(p); 462 continue; 463 } 464 /* 465 * get a limit 466 */ 467 lim_rlimit_proc(p, RLIMIT_RSS, &rsslim); 468 limit = OFF_TO_IDX( 469 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 470 471 /* 472 * let processes that are swapped out really be 473 * swapped out set the limit to nothing (will force a 474 * swap-out.) 475 */ 476 if ((p->p_flag & P_INMEM) == 0) 477 limit = 0; /* XXX */ 478 vm = vmspace_acquire_ref(p); 479 _PHOLD_LITE(p); 480 PROC_UNLOCK(p); 481 if (vm == NULL) { 482 PRELE(p); 483 continue; 484 } 485 sx_sunlock(&allproc_lock); 486 487 size = vmspace_resident_count(vm); 488 if (size >= limit) { 489 vm_swapout_map_deactivate_pages( 490 &vm->vm_map, limit); 491 size = vmspace_resident_count(vm); 492 } 493 #ifdef RACCT 494 if (racct_enable) { 495 rsize = IDX_TO_OFF(size); 496 PROC_LOCK(p); 497 if (p->p_state == PRS_NORMAL) 498 racct_set(p, RACCT_RSS, rsize); 499 ravailable = racct_get_available(p, RACCT_RSS); 500 PROC_UNLOCK(p); 501 if (rsize > ravailable) { 502 /* 503 * Don't be overly aggressive; this 504 * might be an innocent process, 505 * and the limit could've been exceeded 506 * by some memory hog. Don't try 507 * to deactivate more than 1/4th 508 * of process' resident set size. 509 */ 510 if (attempts <= 8) { 511 if (ravailable < rsize - 512 (rsize / 4)) { 513 ravailable = rsize - 514 (rsize / 4); 515 } 516 } 517 vm_swapout_map_deactivate_pages( 518 &vm->vm_map, 519 OFF_TO_IDX(ravailable)); 520 /* Update RSS usage after paging out. */ 521 size = vmspace_resident_count(vm); 522 rsize = IDX_TO_OFF(size); 523 PROC_LOCK(p); 524 if (p->p_state == PRS_NORMAL) 525 racct_set(p, RACCT_RSS, rsize); 526 PROC_UNLOCK(p); 527 if (rsize > ravailable) 528 tryagain = 1; 529 } 530 } 531 #endif 532 vmspace_free(vm); 533 sx_slock(&allproc_lock); 534 PRELE(p); 535 } 536 sx_sunlock(&allproc_lock); 537 if (tryagain != 0 && attempts <= 10) { 538 maybe_yield(); 539 goto again; 540 } 541 } 542 } 543 544 /* 545 * Allow a thread's kernel stack to be paged out. 546 */ 547 static void 548 vm_thread_swapout(struct thread *td) 549 { 550 vm_object_t ksobj; 551 vm_page_t m; 552 int i, pages; 553 554 cpu_thread_swapout(td); 555 pages = td->td_kstack_pages; 556 ksobj = td->td_kstack_obj; 557 pmap_qremove(td->td_kstack, pages); 558 VM_OBJECT_WLOCK(ksobj); 559 for (i = 0; i < pages; i++) { 560 m = vm_page_lookup(ksobj, i); 561 if (m == NULL) 562 panic("vm_thread_swapout: kstack already missing?"); 563 vm_page_dirty(m); 564 vm_page_unwire(m, PQ_LAUNDRY); 565 } 566 VM_OBJECT_WUNLOCK(ksobj); 567 } 568 569 /* 570 * Bring the kernel stack for a specified thread back in. 571 */ 572 static void 573 vm_thread_swapin(struct thread *td, int oom_alloc) 574 { 575 vm_object_t ksobj; 576 vm_page_t ma[KSTACK_MAX_PAGES]; 577 int a, count, i, j, pages, rv; 578 579 pages = td->td_kstack_pages; 580 ksobj = td->td_kstack_obj; 581 VM_OBJECT_WLOCK(ksobj); 582 (void)vm_page_grab_pages(ksobj, 0, oom_alloc | VM_ALLOC_WIRED, ma, 583 pages); 584 for (i = 0; i < pages;) { 585 vm_page_assert_xbusied(ma[i]); 586 if (ma[i]->valid == VM_PAGE_BITS_ALL) { 587 vm_page_xunbusy(ma[i]); 588 i++; 589 continue; 590 } 591 vm_object_pip_add(ksobj, 1); 592 for (j = i + 1; j < pages; j++) 593 if (ma[j]->valid == VM_PAGE_BITS_ALL) 594 break; 595 rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a); 596 KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i])); 597 count = min(a + 1, j - i); 598 rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL); 599 KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d", 600 __func__, td->td_proc->p_pid)); 601 vm_object_pip_wakeup(ksobj); 602 for (j = i; j < i + count; j++) 603 vm_page_xunbusy(ma[j]); 604 i += count; 605 } 606 VM_OBJECT_WUNLOCK(ksobj); 607 pmap_qenter(td->td_kstack, ma, pages); 608 cpu_thread_swapin(td); 609 } 610 611 void 612 faultin(struct proc *p) 613 { 614 struct thread *td; 615 int oom_alloc; 616 617 PROC_LOCK_ASSERT(p, MA_OWNED); 618 619 /* 620 * If another process is swapping in this process, 621 * just wait until it finishes. 622 */ 623 if (p->p_flag & P_SWAPPINGIN) { 624 while (p->p_flag & P_SWAPPINGIN) 625 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 626 return; 627 } 628 629 if ((p->p_flag & P_INMEM) == 0) { 630 oom_alloc = (p->p_flag & P_WKILLED) != 0 ? VM_ALLOC_SYSTEM : 631 VM_ALLOC_NORMAL; 632 633 /* 634 * Don't let another thread swap process p out while we are 635 * busy swapping it in. 636 */ 637 ++p->p_lock; 638 p->p_flag |= P_SWAPPINGIN; 639 PROC_UNLOCK(p); 640 sx_xlock(&allproc_lock); 641 MPASS(swapped_cnt > 0); 642 swapped_cnt--; 643 if (curthread != &thread0) 644 swap_inprogress++; 645 sx_xunlock(&allproc_lock); 646 647 /* 648 * We hold no lock here because the list of threads 649 * can not change while all threads in the process are 650 * swapped out. 651 */ 652 FOREACH_THREAD_IN_PROC(p, td) 653 vm_thread_swapin(td, oom_alloc); 654 655 if (curthread != &thread0) { 656 sx_xlock(&allproc_lock); 657 MPASS(swap_inprogress > 0); 658 swap_inprogress--; 659 last_swapin = ticks; 660 sx_xunlock(&allproc_lock); 661 } 662 PROC_LOCK(p); 663 swapclear(p); 664 p->p_swtick = ticks; 665 666 /* Allow other threads to swap p out now. */ 667 wakeup(&p->p_flag); 668 --p->p_lock; 669 } 670 } 671 672 /* 673 * This swapin algorithm attempts to swap-in processes only if there 674 * is enough space for them. Of course, if a process waits for a long 675 * time, it will be swapped in anyway. 676 */ 677 678 static struct proc * 679 swapper_selector(bool wkilled_only) 680 { 681 struct proc *p, *res; 682 struct thread *td; 683 int ppri, pri, slptime, swtime; 684 685 sx_assert(&allproc_lock, SA_SLOCKED); 686 if (swapped_cnt == 0) 687 return (NULL); 688 res = NULL; 689 ppri = INT_MIN; 690 FOREACH_PROC_IN_SYSTEM(p) { 691 PROC_LOCK(p); 692 if (p->p_state == PRS_NEW || (p->p_flag & (P_SWAPPINGOUT | 693 P_SWAPPINGIN | P_INMEM)) != 0) { 694 PROC_UNLOCK(p); 695 continue; 696 } 697 if (p->p_state == PRS_NORMAL && (p->p_flag & P_WKILLED) != 0) { 698 /* 699 * A swapped-out process might have mapped a 700 * large portion of the system's pages as 701 * anonymous memory. There is no other way to 702 * release the memory other than to kill the 703 * process, for which we need to swap it in. 704 */ 705 return (p); 706 } 707 if (wkilled_only) { 708 PROC_UNLOCK(p); 709 continue; 710 } 711 swtime = (ticks - p->p_swtick) / hz; 712 FOREACH_THREAD_IN_PROC(p, td) { 713 /* 714 * An otherwise runnable thread of a process 715 * swapped out has only the TDI_SWAPPED bit set. 716 */ 717 thread_lock(td); 718 if (td->td_inhibitors == TDI_SWAPPED) { 719 slptime = (ticks - td->td_slptick) / hz; 720 pri = swtime + slptime; 721 if ((td->td_flags & TDF_SWAPINREQ) == 0) 722 pri -= p->p_nice * 8; 723 /* 724 * if this thread is higher priority 725 * and there is enough space, then select 726 * this process instead of the previous 727 * selection. 728 */ 729 if (pri > ppri) { 730 res = p; 731 ppri = pri; 732 } 733 } 734 thread_unlock(td); 735 } 736 PROC_UNLOCK(p); 737 } 738 739 if (res != NULL) 740 PROC_LOCK(res); 741 return (res); 742 } 743 744 #define SWAPIN_INTERVAL (MAXSLP * hz / 2) 745 746 /* 747 * Limit swapper to swap in one non-WKILLED process in MAXSLP/2 748 * interval, assuming that there is: 749 * - at least one domain that is not suffering from a shortage of free memory; 750 * - no parallel swap-ins; 751 * - no other swap-ins in the current SWAPIN_INTERVAL. 752 */ 753 static bool 754 swapper_wkilled_only(void) 755 { 756 757 return (vm_page_count_min_set(&all_domains) || swap_inprogress > 0 || 758 (u_int)(ticks - last_swapin) < SWAPIN_INTERVAL); 759 } 760 761 void 762 swapper(void) 763 { 764 struct proc *p; 765 766 for (;;) { 767 sx_slock(&allproc_lock); 768 p = swapper_selector(swapper_wkilled_only()); 769 sx_sunlock(&allproc_lock); 770 771 if (p == NULL) { 772 tsleep(&proc0, PVM, "swapin", SWAPIN_INTERVAL); 773 } else { 774 PROC_LOCK_ASSERT(p, MA_OWNED); 775 776 /* 777 * Another process may be bringing or may have 778 * already brought this process in while we 779 * traverse all threads. Or, this process may 780 * have exited or even being swapped out 781 * again. 782 */ 783 if (p->p_state == PRS_NORMAL && (p->p_flag & (P_INMEM | 784 P_SWAPPINGOUT | P_SWAPPINGIN)) == 0) { 785 faultin(p); 786 } 787 PROC_UNLOCK(p); 788 } 789 } 790 } 791 792 /* 793 * First, if any processes have been sleeping or stopped for at least 794 * "swap_idle_threshold1" seconds, they are swapped out. If, however, 795 * no such processes exist, then the longest-sleeping or stopped 796 * process is swapped out. Finally, and only as a last resort, if 797 * there are no sleeping or stopped processes, the longest-resident 798 * process is swapped out. 799 */ 800 static void 801 swapout_procs(int action) 802 { 803 struct proc *p; 804 struct thread *td; 805 int slptime; 806 bool didswap, doswap; 807 808 MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0); 809 810 didswap = false; 811 sx_slock(&allproc_lock); 812 FOREACH_PROC_IN_SYSTEM(p) { 813 /* 814 * Filter out not yet fully constructed processes. Do 815 * not swap out held processes. Avoid processes which 816 * are system, exiting, execing, traced, already swapped 817 * out or are in the process of being swapped in or out. 818 */ 819 PROC_LOCK(p); 820 if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag & 821 (P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE | 822 P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) != 823 P_INMEM) { 824 PROC_UNLOCK(p); 825 continue; 826 } 827 828 /* 829 * Further consideration of this process for swap out 830 * requires iterating over its threads. We release 831 * allproc_lock here so that process creation and 832 * destruction are not blocked while we iterate. 833 * 834 * To later reacquire allproc_lock and resume 835 * iteration over the allproc list, we will first have 836 * to release the lock on the process. We place a 837 * hold on the process so that it remains in the 838 * allproc list while it is unlocked. 839 */ 840 _PHOLD_LITE(p); 841 sx_sunlock(&allproc_lock); 842 843 /* 844 * Do not swapout a realtime process. 845 * Guarantee swap_idle_threshold1 time in memory. 846 * If the system is under memory stress, or if we are 847 * swapping idle processes >= swap_idle_threshold2, 848 * then swap the process out. 849 */ 850 doswap = true; 851 FOREACH_THREAD_IN_PROC(p, td) { 852 thread_lock(td); 853 slptime = (ticks - td->td_slptick) / hz; 854 if (PRI_IS_REALTIME(td->td_pri_class) || 855 slptime < swap_idle_threshold1 || 856 !thread_safetoswapout(td) || 857 ((action & VM_SWAP_NORMAL) == 0 && 858 slptime < swap_idle_threshold2)) 859 doswap = false; 860 thread_unlock(td); 861 if (!doswap) 862 break; 863 } 864 if (doswap && swapout(p) == 0) 865 didswap = true; 866 867 PROC_UNLOCK(p); 868 if (didswap) { 869 sx_xlock(&allproc_lock); 870 swapped_cnt++; 871 sx_downgrade(&allproc_lock); 872 } else 873 sx_slock(&allproc_lock); 874 PRELE(p); 875 } 876 sx_sunlock(&allproc_lock); 877 878 /* 879 * If we swapped something out, and another process needed memory, 880 * then wakeup the sched process. 881 */ 882 if (didswap) 883 wakeup(&proc0); 884 } 885 886 static void 887 swapclear(struct proc *p) 888 { 889 struct thread *td; 890 891 PROC_LOCK_ASSERT(p, MA_OWNED); 892 893 FOREACH_THREAD_IN_PROC(p, td) { 894 thread_lock(td); 895 td->td_flags |= TDF_INMEM; 896 td->td_flags &= ~TDF_SWAPINREQ; 897 TD_CLR_SWAPPED(td); 898 if (TD_CAN_RUN(td)) 899 if (setrunnable(td)) { 900 #ifdef INVARIANTS 901 /* 902 * XXX: We just cleared TDI_SWAPPED 903 * above and set TDF_INMEM, so this 904 * should never happen. 905 */ 906 panic("not waking up swapper"); 907 #endif 908 } 909 thread_unlock(td); 910 } 911 p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT); 912 p->p_flag |= P_INMEM; 913 } 914 915 static int 916 swapout(struct proc *p) 917 { 918 struct thread *td; 919 920 PROC_LOCK_ASSERT(p, MA_OWNED); 921 922 /* 923 * The states of this process and its threads may have changed 924 * by now. Assuming that there is only one pageout daemon thread, 925 * this process should still be in memory. 926 */ 927 KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) == 928 P_INMEM, ("swapout: lost a swapout race?")); 929 930 /* 931 * Remember the resident count. 932 */ 933 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 934 935 /* 936 * Check and mark all threads before we proceed. 937 */ 938 p->p_flag &= ~P_INMEM; 939 p->p_flag |= P_SWAPPINGOUT; 940 FOREACH_THREAD_IN_PROC(p, td) { 941 thread_lock(td); 942 if (!thread_safetoswapout(td)) { 943 thread_unlock(td); 944 swapclear(p); 945 return (EBUSY); 946 } 947 td->td_flags &= ~TDF_INMEM; 948 TD_SET_SWAPPED(td); 949 thread_unlock(td); 950 } 951 td = FIRST_THREAD_IN_PROC(p); 952 ++td->td_ru.ru_nswap; 953 PROC_UNLOCK(p); 954 955 /* 956 * This list is stable because all threads are now prevented from 957 * running. The list is only modified in the context of a running 958 * thread in this process. 959 */ 960 FOREACH_THREAD_IN_PROC(p, td) 961 vm_thread_swapout(td); 962 963 PROC_LOCK(p); 964 p->p_flag &= ~P_SWAPPINGOUT; 965 p->p_swtick = ticks; 966 return (0); 967 } 968