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(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 static void 174 vm_swapout_object_deactivate_page(pmap_t pmap, vm_page_t m, bool unmap) 175 { 176 int act_delta; 177 178 if (vm_page_tryxbusy(m) == 0) 179 return; 180 VM_CNT_INC(v_pdpages); 181 182 /* 183 * The page may acquire a wiring after this check. 184 * The page daemon handles wired pages, so there is 185 * no harm done if a wiring appears while we are 186 * attempting to deactivate the page. 187 */ 188 if (vm_page_wired(m) || !pmap_page_exists_quick(pmap, m)) { 189 vm_page_xunbusy(m); 190 return; 191 } 192 act_delta = pmap_ts_referenced(m); 193 vm_page_lock(m); 194 if ((m->a.flags & PGA_REFERENCED) != 0) { 195 if (act_delta == 0) 196 act_delta = 1; 197 vm_page_aflag_clear(m, PGA_REFERENCED); 198 } 199 if (!vm_page_active(m) && act_delta != 0) { 200 vm_page_activate(m); 201 m->a.act_count += act_delta; 202 } else if (vm_page_active(m)) { 203 /* 204 * The page daemon does not requeue pages 205 * after modifying their activation count. 206 */ 207 if (act_delta == 0) { 208 m->a.act_count -= min(m->a.act_count, ACT_DECLINE); 209 if (unmap && m->a.act_count == 0) { 210 (void)vm_page_try_remove_all(m); 211 vm_page_deactivate(m); 212 } 213 } else { 214 vm_page_activate(m); 215 if (m->a.act_count < ACT_MAX - ACT_ADVANCE) 216 m->a.act_count += ACT_ADVANCE; 217 } 218 } else if (vm_page_inactive(m)) 219 (void)vm_page_try_remove_all(m); 220 vm_page_unlock(m); 221 vm_page_xunbusy(m); 222 } 223 224 /* 225 * vm_swapout_object_deactivate 226 * 227 * Deactivate enough pages to satisfy the inactive target 228 * requirements. 229 * 230 * The object and map must be locked. 231 */ 232 static void 233 vm_swapout_object_deactivate(pmap_t pmap, vm_object_t first_object, 234 long desired) 235 { 236 vm_object_t backing_object, object; 237 vm_page_t m; 238 bool unmap; 239 240 VM_OBJECT_ASSERT_LOCKED(first_object); 241 if ((first_object->flags & OBJ_FICTITIOUS) != 0) 242 return; 243 for (object = first_object;; object = backing_object) { 244 if (pmap_resident_count(pmap) <= desired) 245 goto unlock_return; 246 VM_OBJECT_ASSERT_LOCKED(object); 247 if ((object->flags & OBJ_UNMANAGED) != 0 || 248 REFCOUNT_COUNT(object->paging_in_progress) > 0) 249 goto unlock_return; 250 251 unmap = true; 252 if (object->shadow_count > 1) 253 unmap = false; 254 255 /* 256 * Scan the object's entire memory queue. 257 */ 258 TAILQ_FOREACH(m, &object->memq, listq) { 259 if (pmap_resident_count(pmap) <= desired) 260 goto unlock_return; 261 if (should_yield()) 262 goto unlock_return; 263 vm_swapout_object_deactivate_page(pmap, m, unmap); 264 } 265 if ((backing_object = object->backing_object) == NULL) 266 goto unlock_return; 267 VM_OBJECT_RLOCK(backing_object); 268 if (object != first_object) 269 VM_OBJECT_RUNLOCK(object); 270 } 271 unlock_return: 272 if (object != first_object) 273 VM_OBJECT_RUNLOCK(object); 274 } 275 276 /* 277 * deactivate some number of pages in a map, try to do it fairly, but 278 * that is really hard to do. 279 */ 280 static void 281 vm_swapout_map_deactivate_pages(vm_map_t map, long desired) 282 { 283 vm_map_entry_t tmpe; 284 vm_object_t obj, bigobj; 285 int nothingwired; 286 287 if (!vm_map_trylock_read(map)) 288 return; 289 290 bigobj = NULL; 291 nothingwired = TRUE; 292 293 /* 294 * first, search out the biggest object, and try to free pages from 295 * that. 296 */ 297 VM_MAP_ENTRY_FOREACH(tmpe, map) { 298 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 299 obj = tmpe->object.vm_object; 300 if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) { 301 if (obj->shadow_count <= 1 && 302 (bigobj == NULL || 303 bigobj->resident_page_count < 304 obj->resident_page_count)) { 305 if (bigobj != NULL) 306 VM_OBJECT_RUNLOCK(bigobj); 307 bigobj = obj; 308 } else 309 VM_OBJECT_RUNLOCK(obj); 310 } 311 } 312 if (tmpe->wired_count > 0) 313 nothingwired = FALSE; 314 } 315 316 if (bigobj != NULL) { 317 vm_swapout_object_deactivate(map->pmap, bigobj, desired); 318 VM_OBJECT_RUNLOCK(bigobj); 319 } 320 /* 321 * Next, hunt around for other pages to deactivate. We actually 322 * do this search sort of wrong -- .text first is not the best idea. 323 */ 324 VM_MAP_ENTRY_FOREACH(tmpe, map) { 325 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 326 break; 327 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 328 obj = tmpe->object.vm_object; 329 if (obj != NULL) { 330 VM_OBJECT_RLOCK(obj); 331 vm_swapout_object_deactivate(map->pmap, obj, 332 desired); 333 VM_OBJECT_RUNLOCK(obj); 334 } 335 } 336 } 337 338 /* 339 * Remove all mappings if a process is swapped out, this will free page 340 * table pages. 341 */ 342 if (desired == 0 && nothingwired) { 343 pmap_remove(vm_map_pmap(map), vm_map_min(map), 344 vm_map_max(map)); 345 } 346 347 vm_map_unlock_read(map); 348 } 349 350 /* 351 * Swap out requests 352 */ 353 #define VM_SWAP_NORMAL 1 354 #define VM_SWAP_IDLE 2 355 356 void 357 vm_swapout_run(void) 358 { 359 360 if (vm_swap_enabled) 361 vm_req_vmdaemon(VM_SWAP_NORMAL); 362 } 363 364 /* 365 * Idle process swapout -- run once per second when pagedaemons are 366 * reclaiming pages. 367 */ 368 void 369 vm_swapout_run_idle(void) 370 { 371 static long lsec; 372 373 if (!vm_swap_idle_enabled || time_second == lsec) 374 return; 375 vm_req_vmdaemon(VM_SWAP_IDLE); 376 lsec = time_second; 377 } 378 379 static void 380 vm_req_vmdaemon(int req) 381 { 382 static int lastrun = 0; 383 384 mtx_lock(&vm_daemon_mtx); 385 vm_pageout_req_swapout |= req; 386 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 387 wakeup(&vm_daemon_needed); 388 lastrun = ticks; 389 } 390 mtx_unlock(&vm_daemon_mtx); 391 } 392 393 static void 394 vm_daemon(void) 395 { 396 struct rlimit rsslim; 397 struct proc *p; 398 struct thread *td; 399 struct vmspace *vm; 400 int breakout, swapout_flags, tryagain, attempts; 401 #ifdef RACCT 402 uint64_t rsize, ravailable; 403 #endif 404 405 while (TRUE) { 406 mtx_lock(&vm_daemon_mtx); 407 msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 408 #ifdef RACCT 409 racct_enable ? hz : 0 410 #else 411 0 412 #endif 413 ); 414 swapout_flags = vm_pageout_req_swapout; 415 vm_pageout_req_swapout = 0; 416 mtx_unlock(&vm_daemon_mtx); 417 if (swapout_flags != 0) { 418 /* 419 * Drain the per-CPU page queue batches as a deadlock 420 * avoidance measure. 421 */ 422 if ((swapout_flags & VM_SWAP_NORMAL) != 0) 423 vm_page_pqbatch_drain(); 424 swapout_procs(swapout_flags); 425 } 426 427 /* 428 * scan the processes for exceeding their rlimits or if 429 * process is swapped out -- deactivate pages 430 */ 431 tryagain = 0; 432 attempts = 0; 433 again: 434 attempts++; 435 sx_slock(&allproc_lock); 436 FOREACH_PROC_IN_SYSTEM(p) { 437 vm_pindex_t limit, size; 438 439 /* 440 * if this is a system process or if we have already 441 * looked at this process, skip it. 442 */ 443 PROC_LOCK(p); 444 if (p->p_state != PRS_NORMAL || 445 p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { 446 PROC_UNLOCK(p); 447 continue; 448 } 449 /* 450 * if the process is in a non-running type state, 451 * don't touch it. 452 */ 453 breakout = 0; 454 FOREACH_THREAD_IN_PROC(p, td) { 455 thread_lock(td); 456 if (!TD_ON_RUNQ(td) && 457 !TD_IS_RUNNING(td) && 458 !TD_IS_SLEEPING(td) && 459 !TD_IS_SUSPENDED(td)) { 460 thread_unlock(td); 461 breakout = 1; 462 break; 463 } 464 thread_unlock(td); 465 } 466 if (breakout) { 467 PROC_UNLOCK(p); 468 continue; 469 } 470 /* 471 * get a limit 472 */ 473 lim_rlimit_proc(p, RLIMIT_RSS, &rsslim); 474 limit = OFF_TO_IDX( 475 qmin(rsslim.rlim_cur, rsslim.rlim_max)); 476 477 /* 478 * let processes that are swapped out really be 479 * swapped out set the limit to nothing (will force a 480 * swap-out.) 481 */ 482 if ((p->p_flag & P_INMEM) == 0) 483 limit = 0; /* XXX */ 484 vm = vmspace_acquire_ref(p); 485 _PHOLD_LITE(p); 486 PROC_UNLOCK(p); 487 if (vm == NULL) { 488 PRELE(p); 489 continue; 490 } 491 sx_sunlock(&allproc_lock); 492 493 size = vmspace_resident_count(vm); 494 if (size >= limit) { 495 vm_swapout_map_deactivate_pages( 496 &vm->vm_map, limit); 497 size = vmspace_resident_count(vm); 498 } 499 #ifdef RACCT 500 if (racct_enable) { 501 rsize = IDX_TO_OFF(size); 502 PROC_LOCK(p); 503 if (p->p_state == PRS_NORMAL) 504 racct_set(p, RACCT_RSS, rsize); 505 ravailable = racct_get_available(p, RACCT_RSS); 506 PROC_UNLOCK(p); 507 if (rsize > ravailable) { 508 /* 509 * Don't be overly aggressive; this 510 * might be an innocent process, 511 * and the limit could've been exceeded 512 * by some memory hog. Don't try 513 * to deactivate more than 1/4th 514 * of process' resident set size. 515 */ 516 if (attempts <= 8) { 517 if (ravailable < rsize - 518 (rsize / 4)) { 519 ravailable = rsize - 520 (rsize / 4); 521 } 522 } 523 vm_swapout_map_deactivate_pages( 524 &vm->vm_map, 525 OFF_TO_IDX(ravailable)); 526 /* Update RSS usage after paging out. */ 527 size = vmspace_resident_count(vm); 528 rsize = IDX_TO_OFF(size); 529 PROC_LOCK(p); 530 if (p->p_state == PRS_NORMAL) 531 racct_set(p, RACCT_RSS, rsize); 532 PROC_UNLOCK(p); 533 if (rsize > ravailable) 534 tryagain = 1; 535 } 536 } 537 #endif 538 vmspace_free(vm); 539 sx_slock(&allproc_lock); 540 PRELE(p); 541 } 542 sx_sunlock(&allproc_lock); 543 if (tryagain != 0 && attempts <= 10) { 544 maybe_yield(); 545 goto again; 546 } 547 } 548 } 549 550 /* 551 * Allow a thread's kernel stack to be paged out. 552 */ 553 static void 554 vm_thread_swapout(struct thread *td) 555 { 556 vm_object_t ksobj; 557 vm_page_t m; 558 int i, pages; 559 560 cpu_thread_swapout(td); 561 pages = td->td_kstack_pages; 562 ksobj = td->td_kstack_obj; 563 pmap_qremove(td->td_kstack, pages); 564 VM_OBJECT_WLOCK(ksobj); 565 for (i = 0; i < pages; i++) { 566 m = vm_page_lookup(ksobj, i); 567 if (m == NULL) 568 panic("vm_thread_swapout: kstack already missing?"); 569 vm_page_dirty(m); 570 vm_page_unwire(m, PQ_LAUNDRY); 571 } 572 VM_OBJECT_WUNLOCK(ksobj); 573 } 574 575 /* 576 * Bring the kernel stack for a specified thread back in. 577 */ 578 static void 579 vm_thread_swapin(struct thread *td, int oom_alloc) 580 { 581 vm_object_t ksobj; 582 vm_page_t ma[KSTACK_MAX_PAGES]; 583 int a, count, i, j, pages, rv; 584 585 pages = td->td_kstack_pages; 586 ksobj = td->td_kstack_obj; 587 VM_OBJECT_WLOCK(ksobj); 588 (void)vm_page_grab_pages(ksobj, 0, oom_alloc | VM_ALLOC_WIRED, ma, 589 pages); 590 for (i = 0; i < pages;) { 591 vm_page_assert_xbusied(ma[i]); 592 if (vm_page_all_valid(ma[i])) { 593 vm_page_xunbusy(ma[i]); 594 i++; 595 continue; 596 } 597 vm_object_pip_add(ksobj, 1); 598 for (j = i + 1; j < pages; j++) 599 if (vm_page_all_valid(ma[j])) 600 break; 601 rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a); 602 KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i])); 603 count = min(a + 1, j - i); 604 rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL); 605 KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d", 606 __func__, td->td_proc->p_pid)); 607 vm_object_pip_wakeup(ksobj); 608 for (j = i; j < i + count; j++) 609 vm_page_xunbusy(ma[j]); 610 i += count; 611 } 612 VM_OBJECT_WUNLOCK(ksobj); 613 pmap_qenter(td->td_kstack, ma, pages); 614 cpu_thread_swapin(td); 615 } 616 617 void 618 faultin(struct proc *p) 619 { 620 struct thread *td; 621 int oom_alloc; 622 623 PROC_LOCK_ASSERT(p, MA_OWNED); 624 625 /* 626 * If another process is swapping in this process, 627 * just wait until it finishes. 628 */ 629 if (p->p_flag & P_SWAPPINGIN) { 630 while (p->p_flag & P_SWAPPINGIN) 631 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 632 return; 633 } 634 635 if ((p->p_flag & P_INMEM) == 0) { 636 oom_alloc = (p->p_flag & P_WKILLED) != 0 ? VM_ALLOC_SYSTEM : 637 VM_ALLOC_NORMAL; 638 639 /* 640 * Don't let another thread swap process p out while we are 641 * busy swapping it in. 642 */ 643 ++p->p_lock; 644 p->p_flag |= P_SWAPPINGIN; 645 PROC_UNLOCK(p); 646 sx_xlock(&allproc_lock); 647 MPASS(swapped_cnt > 0); 648 swapped_cnt--; 649 if (curthread != &thread0) 650 swap_inprogress++; 651 sx_xunlock(&allproc_lock); 652 653 /* 654 * We hold no lock here because the list of threads 655 * can not change while all threads in the process are 656 * swapped out. 657 */ 658 FOREACH_THREAD_IN_PROC(p, td) 659 vm_thread_swapin(td, oom_alloc); 660 661 if (curthread != &thread0) { 662 sx_xlock(&allproc_lock); 663 MPASS(swap_inprogress > 0); 664 swap_inprogress--; 665 last_swapin = ticks; 666 sx_xunlock(&allproc_lock); 667 } 668 PROC_LOCK(p); 669 swapclear(p); 670 p->p_swtick = ticks; 671 672 /* Allow other threads to swap p out now. */ 673 wakeup(&p->p_flag); 674 --p->p_lock; 675 } 676 } 677 678 /* 679 * This swapin algorithm attempts to swap-in processes only if there 680 * is enough space for them. Of course, if a process waits for a long 681 * time, it will be swapped in anyway. 682 */ 683 684 static struct proc * 685 swapper_selector(bool wkilled_only) 686 { 687 struct proc *p, *res; 688 struct thread *td; 689 int ppri, pri, slptime, swtime; 690 691 sx_assert(&allproc_lock, SA_SLOCKED); 692 if (swapped_cnt == 0) 693 return (NULL); 694 res = NULL; 695 ppri = INT_MIN; 696 FOREACH_PROC_IN_SYSTEM(p) { 697 PROC_LOCK(p); 698 if (p->p_state == PRS_NEW || (p->p_flag & (P_SWAPPINGOUT | 699 P_SWAPPINGIN | P_INMEM)) != 0) { 700 PROC_UNLOCK(p); 701 continue; 702 } 703 if (p->p_state == PRS_NORMAL && (p->p_flag & P_WKILLED) != 0) { 704 /* 705 * A swapped-out process might have mapped a 706 * large portion of the system's pages as 707 * anonymous memory. There is no other way to 708 * release the memory other than to kill the 709 * process, for which we need to swap it in. 710 */ 711 return (p); 712 } 713 if (wkilled_only) { 714 PROC_UNLOCK(p); 715 continue; 716 } 717 swtime = (ticks - p->p_swtick) / hz; 718 FOREACH_THREAD_IN_PROC(p, td) { 719 /* 720 * An otherwise runnable thread of a process 721 * swapped out has only the TDI_SWAPPED bit set. 722 */ 723 thread_lock(td); 724 if (td->td_inhibitors == TDI_SWAPPED) { 725 slptime = (ticks - td->td_slptick) / hz; 726 pri = swtime + slptime; 727 if ((td->td_flags & TDF_SWAPINREQ) == 0) 728 pri -= p->p_nice * 8; 729 /* 730 * if this thread is higher priority 731 * and there is enough space, then select 732 * this process instead of the previous 733 * selection. 734 */ 735 if (pri > ppri) { 736 res = p; 737 ppri = pri; 738 } 739 } 740 thread_unlock(td); 741 } 742 PROC_UNLOCK(p); 743 } 744 745 if (res != NULL) 746 PROC_LOCK(res); 747 return (res); 748 } 749 750 #define SWAPIN_INTERVAL (MAXSLP * hz / 2) 751 752 /* 753 * Limit swapper to swap in one non-WKILLED process in MAXSLP/2 754 * interval, assuming that there is: 755 * - at least one domain that is not suffering from a shortage of free memory; 756 * - no parallel swap-ins; 757 * - no other swap-ins in the current SWAPIN_INTERVAL. 758 */ 759 static bool 760 swapper_wkilled_only(void) 761 { 762 763 return (vm_page_count_min_set(&all_domains) || swap_inprogress > 0 || 764 (u_int)(ticks - last_swapin) < SWAPIN_INTERVAL); 765 } 766 767 void 768 swapper(void) 769 { 770 struct proc *p; 771 772 for (;;) { 773 sx_slock(&allproc_lock); 774 p = swapper_selector(swapper_wkilled_only()); 775 sx_sunlock(&allproc_lock); 776 777 if (p == NULL) { 778 tsleep(&proc0, PVM, "swapin", SWAPIN_INTERVAL); 779 } else { 780 PROC_LOCK_ASSERT(p, MA_OWNED); 781 782 /* 783 * Another process may be bringing or may have 784 * already brought this process in while we 785 * traverse all threads. Or, this process may 786 * have exited or even being swapped out 787 * again. 788 */ 789 if (p->p_state == PRS_NORMAL && (p->p_flag & (P_INMEM | 790 P_SWAPPINGOUT | P_SWAPPINGIN)) == 0) { 791 faultin(p); 792 } 793 PROC_UNLOCK(p); 794 } 795 } 796 } 797 798 /* 799 * First, if any processes have been sleeping or stopped for at least 800 * "swap_idle_threshold1" seconds, they are swapped out. If, however, 801 * no such processes exist, then the longest-sleeping or stopped 802 * process is swapped out. Finally, and only as a last resort, if 803 * there are no sleeping or stopped processes, the longest-resident 804 * process is swapped out. 805 */ 806 static void 807 swapout_procs(int action) 808 { 809 struct proc *p; 810 struct thread *td; 811 int slptime; 812 bool didswap, doswap; 813 814 MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0); 815 816 didswap = false; 817 sx_slock(&allproc_lock); 818 FOREACH_PROC_IN_SYSTEM(p) { 819 /* 820 * Filter out not yet fully constructed processes. Do 821 * not swap out held processes. Avoid processes which 822 * are system, exiting, execing, traced, already swapped 823 * out or are in the process of being swapped in or out. 824 */ 825 PROC_LOCK(p); 826 if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag & 827 (P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE | 828 P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) != 829 P_INMEM) { 830 PROC_UNLOCK(p); 831 continue; 832 } 833 834 /* 835 * Further consideration of this process for swap out 836 * requires iterating over its threads. We release 837 * allproc_lock here so that process creation and 838 * destruction are not blocked while we iterate. 839 * 840 * To later reacquire allproc_lock and resume 841 * iteration over the allproc list, we will first have 842 * to release the lock on the process. We place a 843 * hold on the process so that it remains in the 844 * allproc list while it is unlocked. 845 */ 846 _PHOLD_LITE(p); 847 sx_sunlock(&allproc_lock); 848 849 /* 850 * Do not swapout a realtime process. 851 * Guarantee swap_idle_threshold1 time in memory. 852 * If the system is under memory stress, or if we are 853 * swapping idle processes >= swap_idle_threshold2, 854 * then swap the process out. 855 */ 856 doswap = true; 857 FOREACH_THREAD_IN_PROC(p, td) { 858 thread_lock(td); 859 slptime = (ticks - td->td_slptick) / hz; 860 if (PRI_IS_REALTIME(td->td_pri_class) || 861 slptime < swap_idle_threshold1 || 862 !thread_safetoswapout(td) || 863 ((action & VM_SWAP_NORMAL) == 0 && 864 slptime < swap_idle_threshold2)) 865 doswap = false; 866 thread_unlock(td); 867 if (!doswap) 868 break; 869 } 870 if (doswap && swapout(p) == 0) 871 didswap = true; 872 873 PROC_UNLOCK(p); 874 if (didswap) { 875 sx_xlock(&allproc_lock); 876 swapped_cnt++; 877 sx_downgrade(&allproc_lock); 878 } else 879 sx_slock(&allproc_lock); 880 PRELE(p); 881 } 882 sx_sunlock(&allproc_lock); 883 884 /* 885 * If we swapped something out, and another process needed memory, 886 * then wakeup the sched process. 887 */ 888 if (didswap) 889 wakeup(&proc0); 890 } 891 892 static void 893 swapclear(struct proc *p) 894 { 895 struct thread *td; 896 897 PROC_LOCK_ASSERT(p, MA_OWNED); 898 899 FOREACH_THREAD_IN_PROC(p, td) { 900 thread_lock(td); 901 td->td_flags |= TDF_INMEM; 902 td->td_flags &= ~TDF_SWAPINREQ; 903 TD_CLR_SWAPPED(td); 904 if (TD_CAN_RUN(td)) 905 if (setrunnable(td)) { 906 #ifdef INVARIANTS 907 /* 908 * XXX: We just cleared TDI_SWAPPED 909 * above and set TDF_INMEM, so this 910 * should never happen. 911 */ 912 panic("not waking up swapper"); 913 #endif 914 } 915 thread_unlock(td); 916 } 917 p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT); 918 p->p_flag |= P_INMEM; 919 } 920 921 static int 922 swapout(struct proc *p) 923 { 924 struct thread *td; 925 926 PROC_LOCK_ASSERT(p, MA_OWNED); 927 928 /* 929 * The states of this process and its threads may have changed 930 * by now. Assuming that there is only one pageout daemon thread, 931 * this process should still be in memory. 932 */ 933 KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) == 934 P_INMEM, ("swapout: lost a swapout race?")); 935 936 /* 937 * Remember the resident count. 938 */ 939 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 940 941 /* 942 * Check and mark all threads before we proceed. 943 */ 944 p->p_flag &= ~P_INMEM; 945 p->p_flag |= P_SWAPPINGOUT; 946 FOREACH_THREAD_IN_PROC(p, td) { 947 thread_lock(td); 948 if (!thread_safetoswapout(td)) { 949 thread_unlock(td); 950 swapclear(p); 951 return (EBUSY); 952 } 953 td->td_flags &= ~TDF_INMEM; 954 TD_SET_SWAPPED(td); 955 thread_unlock(td); 956 } 957 td = FIRST_THREAD_IN_PROC(p); 958 ++td->td_ru.ru_nswap; 959 PROC_UNLOCK(p); 960 961 /* 962 * This list is stable because all threads are now prevented from 963 * running. The list is only modified in the context of a running 964 * thread in this process. 965 */ 966 FOREACH_THREAD_IN_PROC(p, td) 967 vm_thread_swapout(td); 968 969 PROC_LOCK(p); 970 p->p_flag &= ~P_SWAPPINGOUT; 971 p->p_swtick = ticks; 972 return (0); 973 } 974