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