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