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/sched.h> 94 #include <sys/sdt.h> 95 #include <sys/signalvar.h> 96 #include <sys/smp.h> 97 #include <sys/time.h> 98 #include <sys/vnode.h> 99 #include <sys/vmmeter.h> 100 #include <sys/rwlock.h> 101 #include <sys/sx.h> 102 #include <sys/sysctl.h> 103 104 #include <vm/vm.h> 105 #include <vm/vm_param.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_pageout_req_swapout; /* XXX */ 155 static int vm_daemon_needed; 156 static struct mtx vm_daemon_mtx; 157 /* Allow for use by vm_pageout before vm_daemon is initialized. */ 158 MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); 159 160 static int swapped_cnt; 161 static int swap_inprogress; /* Pending swap-ins done outside swapper. */ 162 static int last_swapin; 163 164 static void swapclear(struct proc *); 165 static int swapout(struct proc *); 166 static void vm_swapout_map_deactivate_pages(vm_map_t, long); 167 static void vm_swapout_object_deactivate_pages(pmap_t, vm_object_t, long); 168 static void swapout_procs(int action); 169 static void vm_req_vmdaemon(int req); 170 static void vm_thread_swapout(struct thread *td); 171 172 /* 173 * vm_swapout_object_deactivate_pages 174 * 175 * Deactivate enough pages to satisfy the inactive target 176 * requirements. 177 * 178 * The object and map must be locked. 179 */ 180 static void 181 vm_swapout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, 182 long desired) 183 { 184 vm_object_t backing_object, object; 185 vm_page_t p; 186 int act_delta, remove_mode; 187 188 VM_OBJECT_ASSERT_LOCKED(first_object); 189 if ((first_object->flags & OBJ_FICTITIOUS) != 0) 190 return; 191 for (object = first_object;; object = backing_object) { 192 if (pmap_resident_count(pmap) <= desired) 193 goto unlock_return; 194 VM_OBJECT_ASSERT_LOCKED(object); 195 if ((object->flags & OBJ_UNMANAGED) != 0 || 196 object->paging_in_progress != 0) 197 goto unlock_return; 198 199 remove_mode = 0; 200 if (object->shadow_count > 1) 201 remove_mode = 1; 202 /* 203 * Scan the object's entire memory queue. 204 */ 205 TAILQ_FOREACH(p, &object->memq, listq) { 206 if (pmap_resident_count(pmap) <= desired) 207 goto unlock_return; 208 if (should_yield()) 209 goto unlock_return; 210 if (vm_page_busied(p)) 211 continue; 212 VM_CNT_INC(v_pdpages); 213 vm_page_lock(p); 214 if (vm_page_wired(p) || 215 !pmap_page_exists_quick(pmap, p)) { 216 vm_page_unlock(p); 217 continue; 218 } 219 act_delta = pmap_ts_referenced(p); 220 if ((p->aflags & PGA_REFERENCED) != 0) { 221 if (act_delta == 0) 222 act_delta = 1; 223 vm_page_aflag_clear(p, PGA_REFERENCED); 224 } 225 if (!vm_page_active(p) && act_delta != 0) { 226 vm_page_activate(p); 227 p->act_count += act_delta; 228 } else if (vm_page_active(p)) { 229 if (act_delta == 0) { 230 p->act_count -= min(p->act_count, 231 ACT_DECLINE); 232 if (!remove_mode && p->act_count == 0) { 233 pmap_remove_all(p); 234 vm_page_deactivate(p); 235 } else 236 vm_page_requeue(p); 237 } else { 238 vm_page_activate(p); 239 if (p->act_count < ACT_MAX - 240 ACT_ADVANCE) 241 p->act_count += ACT_ADVANCE; 242 vm_page_requeue(p); 243 } 244 } else if (vm_page_inactive(p)) 245 pmap_remove_all(p); 246 vm_page_unlock(p); 247 } 248 if ((backing_object = object->backing_object) == NULL) 249 goto unlock_return; 250 VM_OBJECT_RLOCK(backing_object); 251 if (object != first_object) 252 VM_OBJECT_RUNLOCK(object); 253 } 254 unlock_return: 255 if (object != first_object) 256 VM_OBJECT_RUNLOCK(object); 257 } 258 259 /* 260 * deactivate some number of pages in a map, try to do it fairly, but 261 * that is really hard to do. 262 */ 263 static void 264 vm_swapout_map_deactivate_pages(vm_map_t map, long desired) 265 { 266 vm_map_entry_t tmpe; 267 vm_object_t obj, bigobj; 268 int nothingwired; 269 270 if (!vm_map_trylock_read(map)) 271 return; 272 273 bigobj = NULL; 274 nothingwired = TRUE; 275 276 /* 277 * first, search out the biggest object, and try to free pages from 278 * that. 279 */ 280 tmpe = map->header.next; 281 while (tmpe != &map->header) { 282 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 283 obj = tmpe->object.vm_object; 284 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) { 285 if (obj->shadow_count <= 1 && 286 (bigobj == NULL || 287 bigobj->resident_page_count < 288 obj->resident_page_count)) { 289 if (bigobj != NULL) 290 VM_OBJECT_RUNLOCK(bigobj); 291 bigobj = obj; 292 } else 293 VM_OBJECT_RUNLOCK(obj); 294 } 295 } 296 if (tmpe->wired_count > 0) 297 nothingwired = FALSE; 298 tmpe = tmpe->next; 299 } 300 301 if (bigobj != NULL) { 302 vm_swapout_object_deactivate_pages(map->pmap, bigobj, desired); 303 VM_OBJECT_RUNLOCK(bigobj); 304 } 305 /* 306 * Next, hunt around for other pages to deactivate. We actually 307 * do this search sort of wrong -- .text first is not the best idea. 308 */ 309 tmpe = map->header.next; 310 while (tmpe != &map->header) { 311 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 312 break; 313 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 314 obj = tmpe->object.vm_object; 315 if (obj != NULL) { 316 VM_OBJECT_RLOCK(obj); 317 vm_swapout_object_deactivate_pages(map->pmap, 318 obj, desired); 319 VM_OBJECT_RUNLOCK(obj); 320 } 321 } 322 tmpe = tmpe->next; 323 } 324 325 /* 326 * Remove all mappings if a process is swapped out, this will free page 327 * table pages. 328 */ 329 if (desired == 0 && nothingwired) { 330 pmap_remove(vm_map_pmap(map), vm_map_min(map), 331 vm_map_max(map)); 332 } 333 334 vm_map_unlock_read(map); 335 } 336 337 /* 338 * Swap out requests 339 */ 340 #define VM_SWAP_NORMAL 1 341 #define VM_SWAP_IDLE 2 342 343 void 344 vm_swapout_run(void) 345 { 346 347 if (vm_swap_enabled) 348 vm_req_vmdaemon(VM_SWAP_NORMAL); 349 } 350 351 /* 352 * Idle process swapout -- run once per second when pagedaemons are 353 * reclaiming pages. 354 */ 355 void 356 vm_swapout_run_idle(void) 357 { 358 static long lsec; 359 360 if (!vm_swap_idle_enabled || time_second == lsec) 361 return; 362 vm_req_vmdaemon(VM_SWAP_IDLE); 363 lsec = time_second; 364 } 365 366 static void 367 vm_req_vmdaemon(int req) 368 { 369 static int lastrun = 0; 370 371 mtx_lock(&vm_daemon_mtx); 372 vm_pageout_req_swapout |= req; 373 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 374 wakeup(&vm_daemon_needed); 375 lastrun = ticks; 376 } 377 mtx_unlock(&vm_daemon_mtx); 378 } 379 380 static void 381 vm_daemon(void) 382 { 383 struct rlimit rsslim; 384 struct proc *p; 385 struct thread *td; 386 struct vmspace *vm; 387 int breakout, swapout_flags, tryagain, attempts; 388 #ifdef RACCT 389 uint64_t rsize, ravailable; 390 #endif 391 392 while (TRUE) { 393 mtx_lock(&vm_daemon_mtx); 394 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 395 #ifdef RACCT 396 racct_enable ? hz : 0 397 #else 398 0 399 #endif 400 ); 401 swapout_flags = vm_pageout_req_swapout; 402 vm_pageout_req_swapout = 0; 403 mtx_unlock(&vm_daemon_mtx); 404 if (swapout_flags != 0) { 405 /* 406 * Drain the per-CPU page queue batches as a deadlock 407 * avoidance measure. 408 */ 409 if ((swapout_flags & VM_SWAP_NORMAL) != 0) 410 vm_page_drain_pqbatch(); 411 swapout_procs(swapout_flags); 412 } 413 414 /* 415 * scan the processes for exceeding their rlimits or if 416 * process is swapped out -- deactivate pages 417 */ 418 tryagain = 0; 419 attempts = 0; 420 again: 421 attempts++; 422 sx_slock(&allproc_lock); 423 FOREACH_PROC_IN_SYSTEM(p) { 424 vm_pindex_t limit, size; 425 426 /* 427 * if this is a system process or if we have already 428 * looked at this process, skip it. 429 */ 430 PROC_LOCK(p); 431 if (p->p_state != PRS_NORMAL || 432 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 433 PROC_UNLOCK(p); 434 continue; 435 } 436 /* 437 * if the process is in a non-running type state, 438 * don't touch it. 439 */ 440 breakout = 0; 441 FOREACH_THREAD_IN_PROC(p, td) { 442 thread_lock(td); 443 if (!TD_ON_RUNQ(td) && 444 !TD_IS_RUNNING(td) && 445 !TD_IS_SLEEPING(td) && 446 !TD_IS_SUSPENDED(td)) { 447 thread_unlock(td); 448 breakout = 1; 449 break; 450 } 451 thread_unlock(td); 452 } 453 if (breakout) { 454 PROC_UNLOCK(p); 455 continue; 456 } 457 /* 458 * get a limit 459 */ 460 lim_rlimit_proc(p, RLIMIT_RSS, &rsslim); 461 limit = OFF_TO_IDX( 462 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 463 464 /* 465 * let processes that are swapped out really be 466 * swapped out set the limit to nothing (will force a 467 * swap-out.) 468 */ 469 if ((p->p_flag & P_INMEM) == 0) 470 limit = 0; /* XXX */ 471 vm = vmspace_acquire_ref(p); 472 _PHOLD_LITE(p); 473 PROC_UNLOCK(p); 474 if (vm == NULL) { 475 PRELE(p); 476 continue; 477 } 478 sx_sunlock(&allproc_lock); 479 480 size = vmspace_resident_count(vm); 481 if (size >= limit) { 482 vm_swapout_map_deactivate_pages( 483 &vm->vm_map, limit); 484 size = vmspace_resident_count(vm); 485 } 486 #ifdef RACCT 487 if (racct_enable) { 488 rsize = IDX_TO_OFF(size); 489 PROC_LOCK(p); 490 if (p->p_state == PRS_NORMAL) 491 racct_set(p, RACCT_RSS, rsize); 492 ravailable = racct_get_available(p, RACCT_RSS); 493 PROC_UNLOCK(p); 494 if (rsize > ravailable) { 495 /* 496 * Don't be overly aggressive; this 497 * might be an innocent process, 498 * and the limit could've been exceeded 499 * by some memory hog. Don't try 500 * to deactivate more than 1/4th 501 * of process' resident set size. 502 */ 503 if (attempts <= 8) { 504 if (ravailable < rsize - 505 (rsize / 4)) { 506 ravailable = rsize - 507 (rsize / 4); 508 } 509 } 510 vm_swapout_map_deactivate_pages( 511 &vm->vm_map, 512 OFF_TO_IDX(ravailable)); 513 /* Update RSS usage after paging out. */ 514 size = vmspace_resident_count(vm); 515 rsize = IDX_TO_OFF(size); 516 PROC_LOCK(p); 517 if (p->p_state == PRS_NORMAL) 518 racct_set(p, RACCT_RSS, rsize); 519 PROC_UNLOCK(p); 520 if (rsize > ravailable) 521 tryagain = 1; 522 } 523 } 524 #endif 525 vmspace_free(vm); 526 sx_slock(&allproc_lock); 527 PRELE(p); 528 } 529 sx_sunlock(&allproc_lock); 530 if (tryagain != 0 && attempts <= 10) { 531 maybe_yield(); 532 goto again; 533 } 534 } 535 } 536 537 /* 538 * Allow a thread's kernel stack to be paged out. 539 */ 540 static void 541 vm_thread_swapout(struct thread *td) 542 { 543 vm_object_t ksobj; 544 vm_page_t m; 545 int i, pages; 546 547 cpu_thread_swapout(td); 548 pages = td->td_kstack_pages; 549 ksobj = td->td_kstack_obj; 550 pmap_qremove(td->td_kstack, pages); 551 VM_OBJECT_WLOCK(ksobj); 552 for (i = 0; i < pages; i++) { 553 m = vm_page_lookup(ksobj, i); 554 if (m == NULL) 555 panic("vm_thread_swapout: kstack already missing?"); 556 vm_page_dirty(m); 557 vm_page_lock(m); 558 vm_page_unwire(m, PQ_LAUNDRY); 559 vm_page_unlock(m); 560 } 561 VM_OBJECT_WUNLOCK(ksobj); 562 } 563 564 /* 565 * Bring the kernel stack for a specified thread back in. 566 */ 567 static void 568 vm_thread_swapin(struct thread *td, int oom_alloc) 569 { 570 vm_object_t ksobj; 571 vm_page_t ma[KSTACK_MAX_PAGES]; 572 int a, count, i, j, pages, rv; 573 574 pages = td->td_kstack_pages; 575 ksobj = td->td_kstack_obj; 576 VM_OBJECT_WLOCK(ksobj); 577 (void)vm_page_grab_pages(ksobj, 0, oom_alloc | VM_ALLOC_WIRED, ma, 578 pages); 579 for (i = 0; i < pages;) { 580 vm_page_assert_xbusied(ma[i]); 581 if (ma[i]->valid == VM_PAGE_BITS_ALL) { 582 vm_page_xunbusy(ma[i]); 583 i++; 584 continue; 585 } 586 vm_object_pip_add(ksobj, 1); 587 for (j = i + 1; j < pages; j++) 588 if (ma[j]->valid == VM_PAGE_BITS_ALL) 589 break; 590 rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a); 591 KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i])); 592 count = min(a + 1, j - i); 593 rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL); 594 KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d", 595 __func__, td->td_proc->p_pid)); 596 vm_object_pip_wakeup(ksobj); 597 for (j = i; j < i + count; j++) 598 vm_page_xunbusy(ma[j]); 599 i += count; 600 } 601 VM_OBJECT_WUNLOCK(ksobj); 602 pmap_qenter(td->td_kstack, ma, pages); 603 cpu_thread_swapin(td); 604 } 605 606 void 607 faultin(struct proc *p) 608 { 609 struct thread *td; 610 int oom_alloc; 611 612 PROC_LOCK_ASSERT(p, MA_OWNED); 613 614 /* 615 * If another process is swapping in this process, 616 * just wait until it finishes. 617 */ 618 if (p->p_flag & P_SWAPPINGIN) { 619 while (p->p_flag & P_SWAPPINGIN) 620 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 621 return; 622 } 623 624 if ((p->p_flag & P_INMEM) == 0) { 625 oom_alloc = (p->p_flag & P_WKILLED) != 0 ? VM_ALLOC_SYSTEM : 626 VM_ALLOC_NORMAL; 627 628 /* 629 * Don't let another thread swap process p out while we are 630 * busy swapping it in. 631 */ 632 ++p->p_lock; 633 p->p_flag |= P_SWAPPINGIN; 634 PROC_UNLOCK(p); 635 sx_xlock(&allproc_lock); 636 MPASS(swapped_cnt > 0); 637 swapped_cnt--; 638 if (curthread != &thread0) 639 swap_inprogress++; 640 sx_xunlock(&allproc_lock); 641 642 /* 643 * We hold no lock here because the list of threads 644 * can not change while all threads in the process are 645 * swapped out. 646 */ 647 FOREACH_THREAD_IN_PROC(p, td) 648 vm_thread_swapin(td, oom_alloc); 649 650 if (curthread != &thread0) { 651 sx_xlock(&allproc_lock); 652 MPASS(swap_inprogress > 0); 653 swap_inprogress--; 654 last_swapin = ticks; 655 sx_xunlock(&allproc_lock); 656 } 657 PROC_LOCK(p); 658 swapclear(p); 659 p->p_swtick = ticks; 660 661 /* Allow other threads to swap p out now. */ 662 wakeup(&p->p_flag); 663 --p->p_lock; 664 } 665 } 666 667 /* 668 * This swapin algorithm attempts to swap-in processes only if there 669 * is enough space for them. Of course, if a process waits for a long 670 * time, it will be swapped in anyway. 671 */ 672 673 static struct proc * 674 swapper_selector(bool wkilled_only) 675 { 676 struct proc *p, *res; 677 struct thread *td; 678 int ppri, pri, slptime, swtime; 679 680 sx_assert(&allproc_lock, SA_SLOCKED); 681 if (swapped_cnt == 0) 682 return (NULL); 683 res = NULL; 684 ppri = INT_MIN; 685 FOREACH_PROC_IN_SYSTEM(p) { 686 PROC_LOCK(p); 687 if (p->p_state == PRS_NEW || (p->p_flag & (P_SWAPPINGOUT | 688 P_SWAPPINGIN | P_INMEM)) != 0) { 689 PROC_UNLOCK(p); 690 continue; 691 } 692 if (p->p_state == PRS_NORMAL && (p->p_flag & P_WKILLED) != 0) { 693 /* 694 * A swapped-out process might have mapped a 695 * large portion of the system's pages as 696 * anonymous memory. There is no other way to 697 * release the memory other than to kill the 698 * process, for which we need to swap it in. 699 */ 700 return (p); 701 } 702 if (wkilled_only) { 703 PROC_UNLOCK(p); 704 continue; 705 } 706 swtime = (ticks - p->p_swtick) / hz; 707 FOREACH_THREAD_IN_PROC(p, td) { 708 /* 709 * An otherwise runnable thread of a process 710 * swapped out has only the TDI_SWAPPED bit set. 711 */ 712 thread_lock(td); 713 if (td->td_inhibitors == TDI_SWAPPED) { 714 slptime = (ticks - td->td_slptick) / hz; 715 pri = swtime + slptime; 716 if ((td->td_flags & TDF_SWAPINREQ) == 0) 717 pri -= p->p_nice * 8; 718 /* 719 * if this thread is higher priority 720 * and there is enough space, then select 721 * this process instead of the previous 722 * selection. 723 */ 724 if (pri > ppri) { 725 res = p; 726 ppri = pri; 727 } 728 } 729 thread_unlock(td); 730 } 731 PROC_UNLOCK(p); 732 } 733 734 if (res != NULL) 735 PROC_LOCK(res); 736 return (res); 737 } 738 739 #define SWAPIN_INTERVAL (MAXSLP * hz / 2) 740 741 /* 742 * Limit swapper to swap in one non-WKILLED process in MAXSLP/2 743 * interval, assuming that there is: 744 * - at least one domain that is not suffering from a shortage of free memory; 745 * - no parallel swap-ins; 746 * - no other swap-ins in the current SWAPIN_INTERVAL. 747 */ 748 static bool 749 swapper_wkilled_only(void) 750 { 751 752 return (vm_page_count_min_set(&all_domains) || swap_inprogress > 0 || 753 (u_int)(ticks - last_swapin) < SWAPIN_INTERVAL); 754 } 755 756 void 757 swapper(void) 758 { 759 struct proc *p; 760 761 for (;;) { 762 sx_slock(&allproc_lock); 763 p = swapper_selector(swapper_wkilled_only()); 764 sx_sunlock(&allproc_lock); 765 766 if (p == NULL) { 767 tsleep(&proc0, PVM, "swapin", SWAPIN_INTERVAL); 768 } else { 769 PROC_LOCK_ASSERT(p, MA_OWNED); 770 771 /* 772 * Another process may be bringing or may have 773 * already brought this process in while we 774 * traverse all threads. Or, this process may 775 * have exited or even being swapped out 776 * again. 777 */ 778 if (p->p_state == PRS_NORMAL && (p->p_flag & (P_INMEM | 779 P_SWAPPINGOUT | P_SWAPPINGIN)) == 0) { 780 faultin(p); 781 } 782 PROC_UNLOCK(p); 783 } 784 } 785 } 786 787 /* 788 * First, if any processes have been sleeping or stopped for at least 789 * "swap_idle_threshold1" seconds, they are swapped out. If, however, 790 * no such processes exist, then the longest-sleeping or stopped 791 * process is swapped out. Finally, and only as a last resort, if 792 * there are no sleeping or stopped processes, the longest-resident 793 * process is swapped out. 794 */ 795 static void 796 swapout_procs(int action) 797 { 798 struct proc *p; 799 struct thread *td; 800 int slptime; 801 bool didswap, doswap; 802 803 MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0); 804 805 didswap = false; 806 sx_slock(&allproc_lock); 807 FOREACH_PROC_IN_SYSTEM(p) { 808 /* 809 * Filter out not yet fully constructed processes. Do 810 * not swap out held processes. Avoid processes which 811 * are system, exiting, execing, traced, already swapped 812 * out or are in the process of being swapped in or out. 813 */ 814 PROC_LOCK(p); 815 if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag & 816 (P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE | 817 P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) != 818 P_INMEM) { 819 PROC_UNLOCK(p); 820 continue; 821 } 822 823 /* 824 * Further consideration of this process for swap out 825 * requires iterating over its threads. We release 826 * allproc_lock here so that process creation and 827 * destruction are not blocked while we iterate. 828 * 829 * To later reacquire allproc_lock and resume 830 * iteration over the allproc list, we will first have 831 * to release the lock on the process. We place a 832 * hold on the process so that it remains in the 833 * allproc list while it is unlocked. 834 */ 835 _PHOLD_LITE(p); 836 sx_sunlock(&allproc_lock); 837 838 /* 839 * Do not swapout a realtime process. 840 * Guarantee swap_idle_threshold1 time in memory. 841 * If the system is under memory stress, or if we are 842 * swapping idle processes >= swap_idle_threshold2, 843 * then swap the process out. 844 */ 845 doswap = true; 846 FOREACH_THREAD_IN_PROC(p, td) { 847 thread_lock(td); 848 slptime = (ticks - td->td_slptick) / hz; 849 if (PRI_IS_REALTIME(td->td_pri_class) || 850 slptime < swap_idle_threshold1 || 851 !thread_safetoswapout(td) || 852 ((action & VM_SWAP_NORMAL) == 0 && 853 slptime < swap_idle_threshold2)) 854 doswap = false; 855 thread_unlock(td); 856 if (!doswap) 857 break; 858 } 859 if (doswap && swapout(p) == 0) 860 didswap = true; 861 862 PROC_UNLOCK(p); 863 if (didswap) { 864 sx_xlock(&allproc_lock); 865 swapped_cnt++; 866 sx_downgrade(&allproc_lock); 867 } else 868 sx_slock(&allproc_lock); 869 PRELE(p); 870 } 871 sx_sunlock(&allproc_lock); 872 873 /* 874 * If we swapped something out, and another process needed memory, 875 * then wakeup the sched process. 876 */ 877 if (didswap) 878 wakeup(&proc0); 879 } 880 881 static void 882 swapclear(struct proc *p) 883 { 884 struct thread *td; 885 886 PROC_LOCK_ASSERT(p, MA_OWNED); 887 888 FOREACH_THREAD_IN_PROC(p, td) { 889 thread_lock(td); 890 td->td_flags |= TDF_INMEM; 891 td->td_flags &= ~TDF_SWAPINREQ; 892 TD_CLR_SWAPPED(td); 893 if (TD_CAN_RUN(td)) 894 if (setrunnable(td)) { 895 #ifdef INVARIANTS 896 /* 897 * XXX: We just cleared TDI_SWAPPED 898 * above and set TDF_INMEM, so this 899 * should never happen. 900 */ 901 panic("not waking up swapper"); 902 #endif 903 } 904 thread_unlock(td); 905 } 906 p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT); 907 p->p_flag |= P_INMEM; 908 } 909 910 static int 911 swapout(struct proc *p) 912 { 913 struct thread *td; 914 915 PROC_LOCK_ASSERT(p, MA_OWNED); 916 917 /* 918 * The states of this process and its threads may have changed 919 * by now. Assuming that there is only one pageout daemon thread, 920 * this process should still be in memory. 921 */ 922 KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) == 923 P_INMEM, ("swapout: lost a swapout race?")); 924 925 /* 926 * Remember the resident count. 927 */ 928 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 929 930 /* 931 * Check and mark all threads before we proceed. 932 */ 933 p->p_flag &= ~P_INMEM; 934 p->p_flag |= P_SWAPPINGOUT; 935 FOREACH_THREAD_IN_PROC(p, td) { 936 thread_lock(td); 937 if (!thread_safetoswapout(td)) { 938 thread_unlock(td); 939 swapclear(p); 940 return (EBUSY); 941 } 942 td->td_flags &= ~TDF_INMEM; 943 TD_SET_SWAPPED(td); 944 thread_unlock(td); 945 } 946 td = FIRST_THREAD_IN_PROC(p); 947 ++td->td_ru.ru_nswap; 948 PROC_UNLOCK(p); 949 950 /* 951 * This list is stable because all threads are now prevented from 952 * running. The list is only modified in the context of a running 953 * thread in this process. 954 */ 955 FOREACH_THREAD_IN_PROC(p, td) 956 vm_thread_swapout(td); 957 958 PROC_LOCK(p); 959 p->p_flag &= ~P_SWAPPINGOUT; 960 p->p_swtick = ticks; 961 return (0); 962 } 963