Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/vm/vm_glue.c
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1 /* 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * The Mach Operating System project at Carnegie-Mellon University. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * from: @(#)vm_glue.c 8.6 (Berkeley) 1/5/94 37 * 38 * 39 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 40 * All rights reserved. 41 * 42 * Permission to use, copy, modify and distribute this software and 43 * its documentation is hereby granted, provided that both the copyright 44 * notice and this permission notice appear in all copies of the 45 * software, derivative works or modified versions, and any portions 46 * thereof, and that both notices appear in supporting documentation. 47 * 48 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 49 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 50 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 51 * 52 * Carnegie Mellon requests users of this software to return to 53 * 54 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 55 * School of Computer Science 56 * Carnegie Mellon University 57 * Pittsburgh PA 15213-3890 58 * 59 * any improvements or extensions that they make and grant Carnegie the 60 * rights to redistribute these changes. 61 * 62 * $FreeBSD: releng/5.1/sys/vm/vm_glue.c 114983 2003-05-13 20:36:02Z jhb $ 63 */ 64 65 #include "opt_vm.h" 66 67 #include <sys/param.h> 68 #include <sys/systm.h> 69 #include <sys/limits.h> 70 #include <sys/lock.h> 71 #include <sys/mutex.h> 72 #include <sys/proc.h> 73 #include <sys/resourcevar.h> 74 #include <sys/shm.h> 75 #include <sys/vmmeter.h> 76 #include <sys/sx.h> 77 #include <sys/sysctl.h> 78 79 #include <sys/kernel.h> 80 #include <sys/ktr.h> 81 #include <sys/unistd.h> 82 83 #include <vm/vm.h> 84 #include <vm/vm_param.h> 85 #include <vm/pmap.h> 86 #include <vm/vm_map.h> 87 #include <vm/vm_page.h> 88 #include <vm/vm_pageout.h> 89 #include <vm/vm_object.h> 90 #include <vm/vm_kern.h> 91 #include <vm/vm_extern.h> 92 #include <vm/vm_pager.h> 93 #include <vm/swap_pager.h> 94 95 #include <sys/user.h> 96 97 extern int maxslp; 98 99 /* 100 * System initialization 101 * 102 * Note: proc0 from proc.h 103 */ 104 static void vm_init_limits(void *); 105 SYSINIT(vm_limits, SI_SUB_VM_CONF, SI_ORDER_FIRST, vm_init_limits, &proc0) 106 107 /* 108 * THIS MUST BE THE LAST INITIALIZATION ITEM!!! 109 * 110 * Note: run scheduling should be divorced from the vm system. 111 */ 112 static void scheduler(void *); 113 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, scheduler, NULL) 114 115 #ifndef NO_SWAPPING 116 static void swapout(struct proc *); 117 static void vm_proc_swapin(struct proc *p); 118 static void vm_proc_swapout(struct proc *p); 119 #endif 120 121 /* 122 * MPSAFE 123 * 124 * WARNING! This code calls vm_map_check_protection() which only checks 125 * the associated vm_map_entry range. It does not determine whether the 126 * contents of the memory is actually readable or writable. In most cases 127 * just checking the vm_map_entry is sufficient within the kernel's address 128 * space. 129 */ 130 int 131 kernacc(addr, len, rw) 132 void *addr; 133 int len, rw; 134 { 135 boolean_t rv; 136 vm_offset_t saddr, eaddr; 137 vm_prot_t prot; 138 139 KASSERT((rw & ~VM_PROT_ALL) == 0, 140 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 141 prot = rw; 142 saddr = trunc_page((vm_offset_t)addr); 143 eaddr = round_page((vm_offset_t)addr + len); 144 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 145 return (rv == TRUE); 146 } 147 148 /* 149 * MPSAFE 150 * 151 * WARNING! This code calls vm_map_check_protection() which only checks 152 * the associated vm_map_entry range. It does not determine whether the 153 * contents of the memory is actually readable or writable. vmapbuf(), 154 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 155 * used in conjuction with this call. 156 */ 157 int 158 useracc(addr, len, rw) 159 void *addr; 160 int len, rw; 161 { 162 boolean_t rv; 163 vm_prot_t prot; 164 vm_map_t map; 165 166 KASSERT((rw & ~VM_PROT_ALL) == 0, 167 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 168 prot = rw; 169 map = &curproc->p_vmspace->vm_map; 170 if ((vm_offset_t)addr + len > vm_map_max(map) || 171 (vm_offset_t)addr + len < (vm_offset_t)addr) { 172 return (FALSE); 173 } 174 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 175 round_page((vm_offset_t)addr + len), prot); 176 return (rv == TRUE); 177 } 178 179 /* 180 * MPSAFE 181 */ 182 void 183 vslock(addr, len) 184 void *addr; 185 u_int len; 186 { 187 188 vm_map_wire(&curproc->p_vmspace->vm_map, trunc_page((vm_offset_t)addr), 189 round_page((vm_offset_t)addr + len), FALSE); 190 } 191 192 /* 193 * MPSAFE 194 */ 195 void 196 vsunlock(addr, len) 197 void *addr; 198 u_int len; 199 { 200 201 vm_map_unwire(&curproc->p_vmspace->vm_map, 202 trunc_page((vm_offset_t)addr), 203 round_page((vm_offset_t)addr + len), FALSE); 204 } 205 206 /* 207 * Create the U area for a new process. 208 * This routine directly affects the fork perf for a process. 209 */ 210 void 211 vm_proc_new(struct proc *p) 212 { 213 vm_page_t ma[UAREA_PAGES]; 214 vm_object_t upobj; 215 vm_offset_t up; 216 vm_page_t m; 217 u_int i; 218 219 /* 220 * Allocate object for the upage. 221 */ 222 upobj = vm_object_allocate(OBJT_DEFAULT, UAREA_PAGES); 223 p->p_upages_obj = upobj; 224 225 /* 226 * Get a kernel virtual address for the U area for this process. 227 */ 228 up = kmem_alloc_nofault(kernel_map, UAREA_PAGES * PAGE_SIZE); 229 if (up == 0) 230 panic("vm_proc_new: upage allocation failed"); 231 p->p_uarea = (struct user *)up; 232 233 for (i = 0; i < UAREA_PAGES; i++) { 234 /* 235 * Get a uarea page. 236 */ 237 m = vm_page_grab(upobj, i, 238 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 239 ma[i] = m; 240 241 vm_page_lock_queues(); 242 vm_page_wakeup(m); 243 vm_page_flag_clear(m, PG_ZERO); 244 m->valid = VM_PAGE_BITS_ALL; 245 vm_page_unlock_queues(); 246 } 247 248 /* 249 * Enter the pages into the kernel address space. 250 */ 251 pmap_qenter(up, ma, UAREA_PAGES); 252 } 253 254 /* 255 * Dispose the U area for a process that has exited. 256 * This routine directly impacts the exit perf of a process. 257 * XXX proc_zone is marked UMA_ZONE_NOFREE, so this should never be called. 258 */ 259 void 260 vm_proc_dispose(struct proc *p) 261 { 262 vm_object_t upobj; 263 vm_offset_t up; 264 vm_page_t m; 265 266 upobj = p->p_upages_obj; 267 VM_OBJECT_LOCK(upobj); 268 if (upobj->resident_page_count != UAREA_PAGES) 269 panic("vm_proc_dispose: incorrect number of pages in upobj"); 270 vm_page_lock_queues(); 271 while ((m = TAILQ_FIRST(&upobj->memq)) != NULL) { 272 vm_page_busy(m); 273 vm_page_unwire(m, 0); 274 vm_page_free(m); 275 } 276 vm_page_unlock_queues(); 277 VM_OBJECT_UNLOCK(upobj); 278 up = (vm_offset_t)p->p_uarea; 279 pmap_qremove(up, UAREA_PAGES); 280 kmem_free(kernel_map, up, UAREA_PAGES * PAGE_SIZE); 281 vm_object_deallocate(upobj); 282 } 283 284 #ifndef NO_SWAPPING 285 /* 286 * Allow the U area for a process to be prejudicially paged out. 287 */ 288 static void 289 vm_proc_swapout(struct proc *p) 290 { 291 vm_object_t upobj; 292 vm_offset_t up; 293 vm_page_t m; 294 295 upobj = p->p_upages_obj; 296 VM_OBJECT_LOCK(upobj); 297 if (upobj->resident_page_count != UAREA_PAGES) 298 panic("vm_proc_dispose: incorrect number of pages in upobj"); 299 vm_page_lock_queues(); 300 TAILQ_FOREACH(m, &upobj->memq, listq) { 301 vm_page_dirty(m); 302 vm_page_unwire(m, 0); 303 } 304 vm_page_unlock_queues(); 305 VM_OBJECT_UNLOCK(upobj); 306 up = (vm_offset_t)p->p_uarea; 307 pmap_qremove(up, UAREA_PAGES); 308 } 309 310 /* 311 * Bring the U area for a specified process back in. 312 */ 313 static void 314 vm_proc_swapin(struct proc *p) 315 { 316 vm_page_t ma[UAREA_PAGES]; 317 vm_object_t upobj; 318 vm_offset_t up; 319 vm_page_t m; 320 int rv; 321 int i; 322 323 upobj = p->p_upages_obj; 324 for (i = 0; i < UAREA_PAGES; i++) { 325 m = vm_page_grab(upobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 326 if (m->valid != VM_PAGE_BITS_ALL) { 327 rv = vm_pager_get_pages(upobj, &m, 1, 0); 328 if (rv != VM_PAGER_OK) 329 panic("vm_proc_swapin: cannot get upage"); 330 } 331 ma[i] = m; 332 } 333 VM_OBJECT_LOCK(upobj); 334 if (upobj->resident_page_count != UAREA_PAGES) 335 panic("vm_proc_swapin: lost pages from upobj"); 336 vm_page_lock_queues(); 337 TAILQ_FOREACH(m, &upobj->memq, listq) { 338 m->valid = VM_PAGE_BITS_ALL; 339 vm_page_wire(m); 340 vm_page_wakeup(m); 341 } 342 vm_page_unlock_queues(); 343 VM_OBJECT_UNLOCK(upobj); 344 up = (vm_offset_t)p->p_uarea; 345 pmap_qenter(up, ma, UAREA_PAGES); 346 } 347 348 /* 349 * Swap in the UAREAs of all processes swapped out to the given device. 350 * The pages in the UAREA are marked dirty and their swap metadata is freed. 351 */ 352 void 353 vm_proc_swapin_all(int devidx) 354 { 355 struct proc *p; 356 vm_object_t object; 357 vm_page_t m; 358 359 retry: 360 sx_slock(&allproc_lock); 361 FOREACH_PROC_IN_SYSTEM(p) { 362 PROC_LOCK(p); 363 object = p->p_upages_obj; 364 if (object != NULL) { 365 VM_OBJECT_LOCK(object); 366 if (swap_pager_isswapped(object, devidx)) { 367 VM_OBJECT_UNLOCK(object); 368 sx_sunlock(&allproc_lock); 369 faultin(p); 370 PROC_UNLOCK(p); 371 VM_OBJECT_LOCK(object); 372 vm_page_lock_queues(); 373 TAILQ_FOREACH(m, &object->memq, listq) 374 vm_page_dirty(m); 375 vm_page_unlock_queues(); 376 swap_pager_freespace(object, 0, 377 object->un_pager.swp.swp_bcount); 378 VM_OBJECT_UNLOCK(object); 379 goto retry; 380 } 381 VM_OBJECT_UNLOCK(object); 382 } 383 PROC_UNLOCK(p); 384 } 385 sx_sunlock(&allproc_lock); 386 } 387 #endif 388 389 /* 390 * Implement fork's actions on an address space. 391 * Here we arrange for the address space to be copied or referenced, 392 * allocate a user struct (pcb and kernel stack), then call the 393 * machine-dependent layer to fill those in and make the new process 394 * ready to run. The new process is set up so that it returns directly 395 * to user mode to avoid stack copying and relocation problems. 396 */ 397 void 398 vm_forkproc(td, p2, td2, flags) 399 struct thread *td; 400 struct proc *p2; 401 struct thread *td2; 402 int flags; 403 { 404 struct proc *p1 = td->td_proc; 405 struct user *up; 406 407 GIANT_REQUIRED; 408 409 if ((flags & RFPROC) == 0) { 410 /* 411 * Divorce the memory, if it is shared, essentially 412 * this changes shared memory amongst threads, into 413 * COW locally. 414 */ 415 if ((flags & RFMEM) == 0) { 416 if (p1->p_vmspace->vm_refcnt > 1) { 417 vmspace_unshare(p1); 418 } 419 } 420 cpu_fork(td, p2, td2, flags); 421 return; 422 } 423 424 if (flags & RFMEM) { 425 p2->p_vmspace = p1->p_vmspace; 426 p1->p_vmspace->vm_refcnt++; 427 } 428 429 while (vm_page_count_severe()) { 430 VM_WAIT; 431 } 432 433 if ((flags & RFMEM) == 0) { 434 p2->p_vmspace = vmspace_fork(p1->p_vmspace); 435 436 pmap_pinit2(vmspace_pmap(p2->p_vmspace)); 437 438 if (p1->p_vmspace->vm_shm) 439 shmfork(p1, p2); 440 } 441 442 /* XXXKSE this is unsatisfactory but should be adequate */ 443 up = p2->p_uarea; 444 MPASS(p2->p_sigacts != NULL); 445 446 /* 447 * p_stats currently points at fields in the user struct 448 * but not at &u, instead at p_addr. Copy parts of 449 * p_stats; zero the rest of p_stats (statistics). 450 */ 451 p2->p_stats = &up->u_stats; 452 bzero(&up->u_stats.pstat_startzero, 453 (unsigned) ((caddr_t) &up->u_stats.pstat_endzero - 454 (caddr_t) &up->u_stats.pstat_startzero)); 455 bcopy(&p1->p_stats->pstat_startcopy, &up->u_stats.pstat_startcopy, 456 ((caddr_t) &up->u_stats.pstat_endcopy - 457 (caddr_t) &up->u_stats.pstat_startcopy)); 458 459 /* 460 * cpu_fork will copy and update the pcb, set up the kernel stack, 461 * and make the child ready to run. 462 */ 463 cpu_fork(td, p2, td2, flags); 464 } 465 466 /* 467 * Called after process has been wait(2)'ed apon and is being reaped. 468 * The idea is to reclaim resources that we could not reclaim while 469 * the process was still executing. 470 */ 471 void 472 vm_waitproc(p) 473 struct proc *p; 474 { 475 476 GIANT_REQUIRED; 477 cpu_wait(p); 478 vmspace_exitfree(p); /* and clean-out the vmspace */ 479 } 480 481 /* 482 * Set default limits for VM system. 483 * Called for proc 0, and then inherited by all others. 484 * 485 * XXX should probably act directly on proc0. 486 */ 487 static void 488 vm_init_limits(udata) 489 void *udata; 490 { 491 struct proc *p = udata; 492 int rss_limit; 493 494 /* 495 * Set up the initial limits on process VM. Set the maximum resident 496 * set size to be half of (reasonably) available memory. Since this 497 * is a soft limit, it comes into effect only when the system is out 498 * of memory - half of main memory helps to favor smaller processes, 499 * and reduces thrashing of the object cache. 500 */ 501 p->p_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 502 p->p_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 503 p->p_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 504 p->p_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 505 /* limit the limit to no less than 2MB */ 506 rss_limit = max(cnt.v_free_count, 512); 507 p->p_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 508 p->p_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 509 } 510 511 void 512 faultin(p) 513 struct proc *p; 514 { 515 #ifdef NO_SWAPPING 516 517 PROC_LOCK_ASSERT(p, MA_OWNED); 518 if ((p->p_sflag & PS_INMEM) == 0) 519 panic("faultin: proc swapped out with NO_SWAPPING!"); 520 #else /* !NO_SWAPPING */ 521 struct thread *td; 522 523 GIANT_REQUIRED; 524 PROC_LOCK_ASSERT(p, MA_OWNED); 525 /* 526 * If another process is swapping in this process, 527 * just wait until it finishes. 528 */ 529 if (p->p_sflag & PS_SWAPPINGIN) 530 msleep(&p->p_sflag, &p->p_mtx, PVM, "faultin", 0); 531 else if ((p->p_sflag & PS_INMEM) == 0) { 532 /* 533 * Don't let another thread swap process p out while we are 534 * busy swapping it in. 535 */ 536 ++p->p_lock; 537 mtx_lock_spin(&sched_lock); 538 p->p_sflag |= PS_SWAPPINGIN; 539 mtx_unlock_spin(&sched_lock); 540 PROC_UNLOCK(p); 541 542 vm_proc_swapin(p); 543 FOREACH_THREAD_IN_PROC(p, td) 544 pmap_swapin_thread(td); 545 546 PROC_LOCK(p); 547 mtx_lock_spin(&sched_lock); 548 p->p_sflag &= ~PS_SWAPPINGIN; 549 p->p_sflag |= PS_INMEM; 550 FOREACH_THREAD_IN_PROC(p, td) { 551 TD_CLR_SWAPPED(td); 552 if (TD_CAN_RUN(td)) 553 setrunnable(td); 554 } 555 mtx_unlock_spin(&sched_lock); 556 557 wakeup(&p->p_sflag); 558 559 /* Allow other threads to swap p out now. */ 560 --p->p_lock; 561 } 562 #endif /* NO_SWAPPING */ 563 } 564 565 /* 566 * This swapin algorithm attempts to swap-in processes only if there 567 * is enough space for them. Of course, if a process waits for a long 568 * time, it will be swapped in anyway. 569 * 570 * XXXKSE - process with the thread with highest priority counts.. 571 * 572 * Giant is still held at this point, to be released in tsleep. 573 */ 574 /* ARGSUSED*/ 575 static void 576 scheduler(dummy) 577 void *dummy; 578 { 579 struct proc *p; 580 struct thread *td; 581 int pri; 582 struct proc *pp; 583 int ppri; 584 585 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 586 /* GIANT_REQUIRED */ 587 588 loop: 589 if (vm_page_count_min()) { 590 VM_WAIT; 591 goto loop; 592 } 593 594 pp = NULL; 595 ppri = INT_MIN; 596 sx_slock(&allproc_lock); 597 FOREACH_PROC_IN_SYSTEM(p) { 598 struct ksegrp *kg; 599 if (p->p_sflag & (PS_INMEM | PS_SWAPPINGOUT | PS_SWAPPINGIN)) { 600 continue; 601 } 602 mtx_lock_spin(&sched_lock); 603 FOREACH_THREAD_IN_PROC(p, td) { 604 /* 605 * An otherwise runnable thread of a process 606 * swapped out has only the TDI_SWAPPED bit set. 607 * 608 */ 609 if (td->td_inhibitors == TDI_SWAPPED) { 610 kg = td->td_ksegrp; 611 pri = p->p_swtime + kg->kg_slptime; 612 if ((p->p_sflag & PS_SWAPINREQ) == 0) { 613 pri -= kg->kg_nice * 8; 614 } 615 616 /* 617 * if this ksegrp is higher priority 618 * and there is enough space, then select 619 * this process instead of the previous 620 * selection. 621 */ 622 if (pri > ppri) { 623 pp = p; 624 ppri = pri; 625 } 626 } 627 } 628 mtx_unlock_spin(&sched_lock); 629 } 630 sx_sunlock(&allproc_lock); 631 632 /* 633 * Nothing to do, back to sleep. 634 */ 635 if ((p = pp) == NULL) { 636 tsleep(&proc0, PVM, "sched", maxslp * hz / 2); 637 goto loop; 638 } 639 PROC_LOCK(p); 640 641 /* 642 * Another process may be bringing or may have already 643 * brought this process in while we traverse all threads. 644 * Or, this process may even be being swapped out again. 645 */ 646 if (p->p_sflag & (PS_INMEM | PS_SWAPPINGOUT | PS_SWAPPINGIN)) { 647 PROC_UNLOCK(p); 648 goto loop; 649 } 650 651 mtx_lock_spin(&sched_lock); 652 p->p_sflag &= ~PS_SWAPINREQ; 653 mtx_unlock_spin(&sched_lock); 654 655 /* 656 * We would like to bring someone in. (only if there is space). 657 * [What checks the space? ] 658 */ 659 faultin(p); 660 PROC_UNLOCK(p); 661 mtx_lock_spin(&sched_lock); 662 p->p_swtime = 0; 663 mtx_unlock_spin(&sched_lock); 664 goto loop; 665 } 666 667 #ifndef NO_SWAPPING 668 669 /* 670 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 671 */ 672 static int swap_idle_threshold1 = 2; 673 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 674 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 675 676 /* 677 * Swap_idle_threshold2 is the time that a process can be idle before 678 * it will be swapped out, if idle swapping is enabled. 679 */ 680 static int swap_idle_threshold2 = 10; 681 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 682 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 683 684 /* 685 * Swapout is driven by the pageout daemon. Very simple, we find eligible 686 * procs and unwire their u-areas. We try to always "swap" at least one 687 * process in case we need the room for a swapin. 688 * If any procs have been sleeping/stopped for at least maxslp seconds, 689 * they are swapped. Else, we swap the longest-sleeping or stopped process, 690 * if any, otherwise the longest-resident process. 691 */ 692 void 693 swapout_procs(action) 694 int action; 695 { 696 struct proc *p; 697 struct thread *td; 698 struct ksegrp *kg; 699 struct proc *outp, *outp2; 700 int outpri, outpri2; 701 int didswap = 0; 702 703 GIANT_REQUIRED; 704 705 outp = outp2 = NULL; 706 outpri = outpri2 = INT_MIN; 707 retry: 708 sx_slock(&allproc_lock); 709 FOREACH_PROC_IN_SYSTEM(p) { 710 struct vmspace *vm; 711 int minslptime = 100000; 712 713 /* 714 * Watch out for a process in 715 * creation. It may have no 716 * address space or lock yet. 717 */ 718 mtx_lock_spin(&sched_lock); 719 if (p->p_state == PRS_NEW) { 720 mtx_unlock_spin(&sched_lock); 721 continue; 722 } 723 mtx_unlock_spin(&sched_lock); 724 725 /* 726 * An aio daemon switches its 727 * address space while running. 728 * Perform a quick check whether 729 * a process has P_SYSTEM. 730 */ 731 if ((p->p_flag & P_SYSTEM) != 0) 732 continue; 733 734 /* 735 * Do not swapout a process that 736 * is waiting for VM data 737 * structures as there is a possible 738 * deadlock. Test this first as 739 * this may block. 740 * 741 * Lock the map until swapout 742 * finishes, or a thread of this 743 * process may attempt to alter 744 * the map. 745 */ 746 PROC_LOCK(p); 747 vm = p->p_vmspace; 748 KASSERT(vm != NULL, 749 ("swapout_procs: a process has no address space")); 750 ++vm->vm_refcnt; 751 PROC_UNLOCK(p); 752 if (!vm_map_trylock(&vm->vm_map)) 753 goto nextproc1; 754 755 PROC_LOCK(p); 756 if (p->p_lock != 0 || 757 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 758 ) != 0) { 759 goto nextproc2; 760 } 761 /* 762 * only aiod changes vmspace, however it will be 763 * skipped because of the if statement above checking 764 * for P_SYSTEM 765 */ 766 if ((p->p_sflag & (PS_INMEM|PS_SWAPPINGOUT|PS_SWAPPINGIN)) != PS_INMEM) 767 goto nextproc2; 768 769 switch (p->p_state) { 770 default: 771 /* Don't swap out processes in any sort 772 * of 'special' state. */ 773 break; 774 775 case PRS_NORMAL: 776 mtx_lock_spin(&sched_lock); 777 /* 778 * do not swapout a realtime process 779 * Check all the thread groups.. 780 */ 781 FOREACH_KSEGRP_IN_PROC(p, kg) { 782 if (PRI_IS_REALTIME(kg->kg_pri_class)) 783 goto nextproc; 784 785 /* 786 * Guarantee swap_idle_threshold1 787 * time in memory. 788 */ 789 if (kg->kg_slptime < swap_idle_threshold1) 790 goto nextproc; 791 792 /* 793 * Do not swapout a process if it is 794 * waiting on a critical event of some 795 * kind or there is a thread whose 796 * pageable memory may be accessed. 797 * 798 * This could be refined to support 799 * swapping out a thread. 800 */ 801 FOREACH_THREAD_IN_GROUP(kg, td) { 802 if ((td->td_priority) < PSOCK || 803 !thread_safetoswapout(td)) 804 goto nextproc; 805 } 806 /* 807 * If the system is under memory stress, 808 * or if we are swapping 809 * idle processes >= swap_idle_threshold2, 810 * then swap the process out. 811 */ 812 if (((action & VM_SWAP_NORMAL) == 0) && 813 (((action & VM_SWAP_IDLE) == 0) || 814 (kg->kg_slptime < swap_idle_threshold2))) 815 goto nextproc; 816 817 if (minslptime > kg->kg_slptime) 818 minslptime = kg->kg_slptime; 819 } 820 821 /* 822 * If the process has been asleep for awhile and had 823 * most of its pages taken away already, swap it out. 824 */ 825 if ((action & VM_SWAP_NORMAL) || 826 ((action & VM_SWAP_IDLE) && 827 (minslptime > swap_idle_threshold2))) { 828 swapout(p); 829 didswap++; 830 mtx_unlock_spin(&sched_lock); 831 PROC_UNLOCK(p); 832 vm_map_unlock(&vm->vm_map); 833 vmspace_free(vm); 834 sx_sunlock(&allproc_lock); 835 goto retry; 836 } 837 nextproc: 838 mtx_unlock_spin(&sched_lock); 839 } 840 nextproc2: 841 PROC_UNLOCK(p); 842 vm_map_unlock(&vm->vm_map); 843 nextproc1: 844 vmspace_free(vm); 845 continue; 846 } 847 sx_sunlock(&allproc_lock); 848 /* 849 * If we swapped something out, and another process needed memory, 850 * then wakeup the sched process. 851 */ 852 if (didswap) 853 wakeup(&proc0); 854 } 855 856 static void 857 swapout(p) 858 struct proc *p; 859 { 860 struct thread *td; 861 862 PROC_LOCK_ASSERT(p, MA_OWNED); 863 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 864 #if defined(SWAP_DEBUG) 865 printf("swapping out %d\n", p->p_pid); 866 #endif 867 868 /* 869 * The states of this process and its threads may have changed 870 * by now. Assuming that there is only one pageout daemon thread, 871 * this process should still be in memory. 872 */ 873 KASSERT((p->p_sflag & (PS_INMEM|PS_SWAPPINGOUT|PS_SWAPPINGIN)) == PS_INMEM, 874 ("swapout: lost a swapout race?")); 875 876 #if defined(INVARIANTS) 877 /* 878 * Make sure that all threads are safe to be swapped out. 879 * 880 * Alternatively, we could swap out only safe threads. 881 */ 882 FOREACH_THREAD_IN_PROC(p, td) { 883 KASSERT(thread_safetoswapout(td), 884 ("swapout: there is a thread not safe for swapout")); 885 } 886 #endif /* INVARIANTS */ 887 888 ++p->p_stats->p_ru.ru_nswap; 889 /* 890 * remember the process resident count 891 */ 892 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 893 894 p->p_sflag &= ~PS_INMEM; 895 p->p_sflag |= PS_SWAPPINGOUT; 896 PROC_UNLOCK(p); 897 FOREACH_THREAD_IN_PROC(p, td) 898 TD_SET_SWAPPED(td); 899 mtx_unlock_spin(&sched_lock); 900 901 vm_proc_swapout(p); 902 FOREACH_THREAD_IN_PROC(p, td) 903 pmap_swapout_thread(td); 904 905 PROC_LOCK(p); 906 mtx_lock_spin(&sched_lock); 907 p->p_sflag &= ~PS_SWAPPINGOUT; 908 p->p_swtime = 0; 909 } 910 #endif /* !NO_SWAPPING */
Cache object: b9ff0253c479f038275ada4e6274869b
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