vm_glue.c revision 138129
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 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * from: @(#)vm_glue.c 8.6 (Berkeley) 1/5/94 33 * 34 * 35 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 36 * All rights reserved. 37 * 38 * Permission to use, copy, modify and distribute this software and 39 * its documentation is hereby granted, provided that both the copyright 40 * notice and this permission notice appear in all copies of the 41 * software, derivative works or modified versions, and any portions 42 * thereof, and that both notices appear in supporting documentation. 43 * 44 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 45 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 46 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 47 * 48 * Carnegie Mellon requests users of this software to return to 49 * 50 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 51 * School of Computer Science 52 * Carnegie Mellon University 53 * Pittsburgh PA 15213-3890 54 * 55 * any improvements or extensions that they make and grant Carnegie the 56 * rights to redistribute these changes. 57 */ 58 59#include <sys/cdefs.h> 60__FBSDID("$FreeBSD: head/sys/vm/vm_glue.c 138129 2004-11-27 06:51:39Z das $"); 61 62#include "opt_vm.h" 63#include "opt_kstack_pages.h" 64#include "opt_kstack_max_pages.h" 65 66#include <sys/param.h> 67#include <sys/systm.h> 68#include <sys/limits.h> 69#include <sys/lock.h> 70#include <sys/mutex.h> 71#include <sys/proc.h> 72#include <sys/resourcevar.h> 73#include <sys/shm.h> 74#include <sys/vmmeter.h> 75#include <sys/sx.h> 76#include <sys/sysctl.h> 77 78#include <sys/kernel.h> 79#include <sys/ktr.h> 80#include <sys/unistd.h> 81 82#include <vm/vm.h> 83#include <vm/vm_param.h> 84#include <vm/pmap.h> 85#include <vm/vm_map.h> 86#include <vm/vm_page.h> 87#include <vm/vm_pageout.h> 88#include <vm/vm_object.h> 89#include <vm/vm_kern.h> 90#include <vm/vm_extern.h> 91#include <vm/vm_pager.h> 92#include <vm/swap_pager.h> 93 94extern int maxslp; 95 96/* 97 * System initialization 98 * 99 * Note: proc0 from proc.h 100 */ 101static void vm_init_limits(void *); 102SYSINIT(vm_limits, SI_SUB_VM_CONF, SI_ORDER_FIRST, vm_init_limits, &proc0) 103 104/* 105 * THIS MUST BE THE LAST INITIALIZATION ITEM!!! 106 * 107 * Note: run scheduling should be divorced from the vm system. 108 */ 109static void scheduler(void *); 110SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY, scheduler, NULL) 111 112#ifndef NO_SWAPPING 113static void swapout(struct proc *); 114#endif 115 116/* 117 * MPSAFE 118 * 119 * WARNING! This code calls vm_map_check_protection() which only checks 120 * the associated vm_map_entry range. It does not determine whether the 121 * contents of the memory is actually readable or writable. In most cases 122 * just checking the vm_map_entry is sufficient within the kernel's address 123 * space. 124 */ 125int 126kernacc(addr, len, rw) 127 void *addr; 128 int len, rw; 129{ 130 boolean_t rv; 131 vm_offset_t saddr, eaddr; 132 vm_prot_t prot; 133 134 KASSERT((rw & ~VM_PROT_ALL) == 0, 135 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 136 prot = rw; 137 saddr = trunc_page((vm_offset_t)addr); 138 eaddr = round_page((vm_offset_t)addr + len); 139 vm_map_lock_read(kernel_map); 140 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 141 vm_map_unlock_read(kernel_map); 142 return (rv == TRUE); 143} 144 145/* 146 * MPSAFE 147 * 148 * WARNING! This code calls vm_map_check_protection() which only checks 149 * the associated vm_map_entry range. It does not determine whether the 150 * contents of the memory is actually readable or writable. vmapbuf(), 151 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 152 * used in conjuction with this call. 153 */ 154int 155useracc(addr, len, rw) 156 void *addr; 157 int len, rw; 158{ 159 boolean_t rv; 160 vm_prot_t prot; 161 vm_map_t map; 162 163 KASSERT((rw & ~VM_PROT_ALL) == 0, 164 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 165 prot = rw; 166 map = &curproc->p_vmspace->vm_map; 167 if ((vm_offset_t)addr + len > vm_map_max(map) || 168 (vm_offset_t)addr + len < (vm_offset_t)addr) { 169 return (FALSE); 170 } 171 vm_map_lock_read(map); 172 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 173 round_page((vm_offset_t)addr + len), prot); 174 vm_map_unlock_read(map); 175 return (rv == TRUE); 176} 177 178int 179vslock(void *addr, size_t len) 180{ 181 vm_offset_t end, last, start; 182 vm_size_t npages; 183 int error; 184 185 last = (vm_offset_t)addr + len; 186 start = trunc_page((vm_offset_t)addr); 187 end = round_page(last); 188 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr) 189 return (EINVAL); 190 npages = atop(end - start); 191 if (npages > vm_page_max_wired) 192 return (ENOMEM); 193 PROC_LOCK(curproc); 194 if (ptoa(npages + 195 pmap_wired_count(vm_map_pmap(&curproc->p_vmspace->vm_map))) > 196 lim_cur(curproc, RLIMIT_MEMLOCK)) { 197 PROC_UNLOCK(curproc); 198 return (ENOMEM); 199 } 200 PROC_UNLOCK(curproc); 201#if 0 202 /* 203 * XXX - not yet 204 * 205 * The limit for transient usage of wired pages should be 206 * larger than for "permanent" wired pages (mlock()). 207 * 208 * Also, the sysctl code, which is the only present user 209 * of vslock(), does a hard loop on EAGAIN. 210 */ 211 if (npages + cnt.v_wire_count > vm_page_max_wired) 212 return (EAGAIN); 213#endif 214 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 215 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 216 /* 217 * Return EFAULT on error to match copy{in,out}() behaviour 218 * rather than returning ENOMEM like mlock() would. 219 */ 220 return (error == KERN_SUCCESS ? 0 : EFAULT); 221} 222 223void 224vsunlock(void *addr, size_t len) 225{ 226 227 /* Rely on the parameter sanity checks performed by vslock(). */ 228 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 229 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 230 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 231} 232 233#ifndef KSTACK_MAX_PAGES 234#define KSTACK_MAX_PAGES 32 235#endif 236 237/* 238 * Create the kernel stack (including pcb for i386) for a new thread. 239 * This routine directly affects the fork perf for a process and 240 * create performance for a thread. 241 */ 242void 243vm_thread_new(struct thread *td, int pages) 244{ 245 vm_object_t ksobj; 246 vm_offset_t ks; 247 vm_page_t m, ma[KSTACK_MAX_PAGES]; 248 int i; 249 250 /* Bounds check */ 251 if (pages <= 1) 252 pages = KSTACK_PAGES; 253 else if (pages > KSTACK_MAX_PAGES) 254 pages = KSTACK_MAX_PAGES; 255 /* 256 * Allocate an object for the kstack. 257 */ 258 ksobj = vm_object_allocate(OBJT_DEFAULT, pages); 259 td->td_kstack_obj = ksobj; 260 /* 261 * Get a kernel virtual address for this thread's kstack. 262 */ 263 ks = kmem_alloc_nofault(kernel_map, 264 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 265 if (ks == 0) 266 panic("vm_thread_new: kstack allocation failed"); 267 if (KSTACK_GUARD_PAGES != 0) { 268 pmap_qremove(ks, KSTACK_GUARD_PAGES); 269 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 270 } 271 td->td_kstack = ks; 272 /* 273 * Knowing the number of pages allocated is useful when you 274 * want to deallocate them. 275 */ 276 td->td_kstack_pages = pages; 277 /* 278 * For the length of the stack, link in a real page of ram for each 279 * page of stack. 280 */ 281 VM_OBJECT_LOCK(ksobj); 282 for (i = 0; i < pages; i++) { 283 /* 284 * Get a kernel stack page. 285 */ 286 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 287 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 288 ma[i] = m; 289 m->valid = VM_PAGE_BITS_ALL; 290 } 291 VM_OBJECT_UNLOCK(ksobj); 292 pmap_qenter(ks, ma, pages); 293} 294 295/* 296 * Dispose of a thread's kernel stack. 297 */ 298void 299vm_thread_dispose(struct thread *td) 300{ 301 vm_object_t ksobj; 302 vm_offset_t ks; 303 vm_page_t m; 304 int i, pages; 305 306 pages = td->td_kstack_pages; 307 ksobj = td->td_kstack_obj; 308 ks = td->td_kstack; 309 pmap_qremove(ks, pages); 310 VM_OBJECT_LOCK(ksobj); 311 for (i = 0; i < pages; i++) { 312 m = vm_page_lookup(ksobj, i); 313 if (m == NULL) 314 panic("vm_thread_dispose: kstack already missing?"); 315 vm_page_lock_queues(); 316 vm_page_unwire(m, 0); 317 vm_page_free(m); 318 vm_page_unlock_queues(); 319 } 320 VM_OBJECT_UNLOCK(ksobj); 321 vm_object_deallocate(ksobj); 322 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 323 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 324} 325 326/* 327 * Allow a thread's kernel stack to be paged out. 328 */ 329void 330vm_thread_swapout(struct thread *td) 331{ 332 vm_object_t ksobj; 333 vm_page_t m; 334 int i, pages; 335 336 cpu_thread_swapout(td); 337 pages = td->td_kstack_pages; 338 ksobj = td->td_kstack_obj; 339 pmap_qremove(td->td_kstack, pages); 340 VM_OBJECT_LOCK(ksobj); 341 for (i = 0; i < pages; i++) { 342 m = vm_page_lookup(ksobj, i); 343 if (m == NULL) 344 panic("vm_thread_swapout: kstack already missing?"); 345 vm_page_lock_queues(); 346 vm_page_dirty(m); 347 vm_page_unwire(m, 0); 348 vm_page_unlock_queues(); 349 } 350 VM_OBJECT_UNLOCK(ksobj); 351} 352 353/* 354 * Bring the kernel stack for a specified thread back in. 355 */ 356void 357vm_thread_swapin(struct thread *td) 358{ 359 vm_object_t ksobj; 360 vm_page_t m, ma[KSTACK_MAX_PAGES]; 361 int i, pages, rv; 362 363 pages = td->td_kstack_pages; 364 ksobj = td->td_kstack_obj; 365 VM_OBJECT_LOCK(ksobj); 366 for (i = 0; i < pages; i++) { 367 m = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 368 if (m->valid != VM_PAGE_BITS_ALL) { 369 rv = vm_pager_get_pages(ksobj, &m, 1, 0); 370 if (rv != VM_PAGER_OK) 371 panic("vm_thread_swapin: cannot get kstack for proc: %d", td->td_proc->p_pid); 372 m = vm_page_lookup(ksobj, i); 373 m->valid = VM_PAGE_BITS_ALL; 374 } 375 ma[i] = m; 376 vm_page_lock_queues(); 377 vm_page_wire(m); 378 vm_page_wakeup(m); 379 vm_page_unlock_queues(); 380 } 381 VM_OBJECT_UNLOCK(ksobj); 382 pmap_qenter(td->td_kstack, ma, pages); 383 cpu_thread_swapin(td); 384} 385 386/* 387 * Set up a variable-sized alternate kstack. 388 */ 389void 390vm_thread_new_altkstack(struct thread *td, int pages) 391{ 392 393 td->td_altkstack = td->td_kstack; 394 td->td_altkstack_obj = td->td_kstack_obj; 395 td->td_altkstack_pages = td->td_kstack_pages; 396 397 vm_thread_new(td, pages); 398} 399 400/* 401 * Restore the original kstack. 402 */ 403void 404vm_thread_dispose_altkstack(struct thread *td) 405{ 406 407 vm_thread_dispose(td); 408 409 td->td_kstack = td->td_altkstack; 410 td->td_kstack_obj = td->td_altkstack_obj; 411 td->td_kstack_pages = td->td_altkstack_pages; 412 td->td_altkstack = 0; 413 td->td_altkstack_obj = NULL; 414 td->td_altkstack_pages = 0; 415} 416 417/* 418 * Implement fork's actions on an address space. 419 * Here we arrange for the address space to be copied or referenced, 420 * allocate a user struct (pcb and kernel stack), then call the 421 * machine-dependent layer to fill those in and make the new process 422 * ready to run. The new process is set up so that it returns directly 423 * to user mode to avoid stack copying and relocation problems. 424 */ 425void 426vm_forkproc(td, p2, td2, flags) 427 struct thread *td; 428 struct proc *p2; 429 struct thread *td2; 430 int flags; 431{ 432 struct proc *p1 = td->td_proc; 433 434 if ((flags & RFPROC) == 0) { 435 /* 436 * Divorce the memory, if it is shared, essentially 437 * this changes shared memory amongst threads, into 438 * COW locally. 439 */ 440 if ((flags & RFMEM) == 0) { 441 if (p1->p_vmspace->vm_refcnt > 1) { 442 vmspace_unshare(p1); 443 } 444 } 445 cpu_fork(td, p2, td2, flags); 446 return; 447 } 448 449 if (flags & RFMEM) { 450 p2->p_vmspace = p1->p_vmspace; 451 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 452 } 453 454 while (vm_page_count_severe()) { 455 VM_WAIT; 456 } 457 458 if ((flags & RFMEM) == 0) { 459 p2->p_vmspace = vmspace_fork(p1->p_vmspace); 460 if (p1->p_vmspace->vm_shm) 461 shmfork(p1, p2); 462 } 463 464 /* 465 * cpu_fork will copy and update the pcb, set up the kernel stack, 466 * and make the child ready to run. 467 */ 468 cpu_fork(td, p2, td2, flags); 469} 470 471/* 472 * Called after process has been wait(2)'ed apon and is being reaped. 473 * The idea is to reclaim resources that we could not reclaim while 474 * the process was still executing. 475 */ 476void 477vm_waitproc(p) 478 struct proc *p; 479{ 480 481 vmspace_exitfree(p); /* and clean-out the vmspace */ 482} 483 484/* 485 * Set default limits for VM system. 486 * Called for proc 0, and then inherited by all others. 487 * 488 * XXX should probably act directly on proc0. 489 */ 490static void 491vm_init_limits(udata) 492 void *udata; 493{ 494 struct proc *p = udata; 495 struct plimit *limp; 496 int rss_limit; 497 498 /* 499 * Set up the initial limits on process VM. Set the maximum resident 500 * set size to be half of (reasonably) available memory. Since this 501 * is a soft limit, it comes into effect only when the system is out 502 * of memory - half of main memory helps to favor smaller processes, 503 * and reduces thrashing of the object cache. 504 */ 505 limp = p->p_limit; 506 limp->pl_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 507 limp->pl_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 508 limp->pl_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 509 limp->pl_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 510 /* limit the limit to no less than 2MB */ 511 rss_limit = max(cnt.v_free_count, 512); 512 limp->pl_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 513 limp->pl_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 514} 515 516void 517faultin(p) 518 struct proc *p; 519{ 520#ifdef NO_SWAPPING 521 522 PROC_LOCK_ASSERT(p, MA_OWNED); 523 if ((p->p_sflag & PS_INMEM) == 0) 524 panic("faultin: proc swapped out with NO_SWAPPING!"); 525#else /* !NO_SWAPPING */ 526 struct thread *td; 527 528 GIANT_REQUIRED; 529 PROC_LOCK_ASSERT(p, MA_OWNED); 530 /* 531 * If another process is swapping in this process, 532 * just wait until it finishes. 533 */ 534 if (p->p_sflag & PS_SWAPPINGIN) 535 msleep(&p->p_sflag, &p->p_mtx, PVM, "faultin", 0); 536 else if ((p->p_sflag & PS_INMEM) == 0) { 537 /* 538 * Don't let another thread swap process p out while we are 539 * busy swapping it in. 540 */ 541 ++p->p_lock; 542 mtx_lock_spin(&sched_lock); 543 p->p_sflag |= PS_SWAPPINGIN; 544 mtx_unlock_spin(&sched_lock); 545 PROC_UNLOCK(p); 546 547 FOREACH_THREAD_IN_PROC(p, td) 548 vm_thread_swapin(td); 549 550 PROC_LOCK(p); 551 mtx_lock_spin(&sched_lock); 552 p->p_sflag &= ~PS_SWAPPINGIN; 553 p->p_sflag |= PS_INMEM; 554 FOREACH_THREAD_IN_PROC(p, td) { 555 TD_CLR_SWAPPED(td); 556 if (TD_CAN_RUN(td)) 557 setrunnable(td); 558 } 559 mtx_unlock_spin(&sched_lock); 560 561 wakeup(&p->p_sflag); 562 563 /* Allow other threads to swap p out now. */ 564 --p->p_lock; 565 } 566#endif /* NO_SWAPPING */ 567} 568 569/* 570 * This swapin algorithm attempts to swap-in processes only if there 571 * is enough space for them. Of course, if a process waits for a long 572 * time, it will be swapped in anyway. 573 * 574 * XXXKSE - process with the thread with highest priority counts.. 575 * 576 * Giant is still held at this point, to be released in tsleep. 577 */ 578/* ARGSUSED*/ 579static void 580scheduler(dummy) 581 void *dummy; 582{ 583 struct proc *p; 584 struct thread *td; 585 int pri; 586 struct proc *pp; 587 int ppri; 588 589 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 590 /* GIANT_REQUIRED */ 591 592loop: 593 if (vm_page_count_min()) { 594 VM_WAIT; 595 goto loop; 596 } 597 598 pp = NULL; 599 ppri = INT_MIN; 600 sx_slock(&allproc_lock); 601 FOREACH_PROC_IN_SYSTEM(p) { 602 struct ksegrp *kg; 603 if (p->p_sflag & (PS_INMEM | PS_SWAPPINGOUT | PS_SWAPPINGIN)) { 604 continue; 605 } 606 mtx_lock_spin(&sched_lock); 607 FOREACH_THREAD_IN_PROC(p, td) { 608 /* 609 * An otherwise runnable thread of a process 610 * swapped out has only the TDI_SWAPPED bit set. 611 * 612 */ 613 if (td->td_inhibitors == TDI_SWAPPED) { 614 kg = td->td_ksegrp; 615 pri = p->p_swtime + kg->kg_slptime; 616 if ((p->p_sflag & PS_SWAPINREQ) == 0) { 617 pri -= p->p_nice * 8; 618 } 619 620 /* 621 * if this ksegrp is higher priority 622 * and there is enough space, then select 623 * this process instead of the previous 624 * selection. 625 */ 626 if (pri > ppri) { 627 pp = p; 628 ppri = pri; 629 } 630 } 631 } 632 mtx_unlock_spin(&sched_lock); 633 } 634 sx_sunlock(&allproc_lock); 635 636 /* 637 * Nothing to do, back to sleep. 638 */ 639 if ((p = pp) == NULL) { 640 tsleep(&proc0, PVM, "sched", maxslp * hz / 2); 641 goto loop; 642 } 643 PROC_LOCK(p); 644 645 /* 646 * Another process may be bringing or may have already 647 * brought this process in while we traverse all threads. 648 * Or, this process may even be being swapped out again. 649 */ 650 if (p->p_sflag & (PS_INMEM | PS_SWAPPINGOUT | PS_SWAPPINGIN)) { 651 PROC_UNLOCK(p); 652 goto loop; 653 } 654 655 mtx_lock_spin(&sched_lock); 656 p->p_sflag &= ~PS_SWAPINREQ; 657 mtx_unlock_spin(&sched_lock); 658 659 /* 660 * We would like to bring someone in. (only if there is space). 661 * [What checks the space? ] 662 */ 663 faultin(p); 664 PROC_UNLOCK(p); 665 mtx_lock_spin(&sched_lock); 666 p->p_swtime = 0; 667 mtx_unlock_spin(&sched_lock); 668 goto loop; 669} 670 671#ifndef NO_SWAPPING 672 673/* 674 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 675 */ 676static int swap_idle_threshold1 = 2; 677SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 678 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 679 680/* 681 * Swap_idle_threshold2 is the time that a process can be idle before 682 * it will be swapped out, if idle swapping is enabled. 683 */ 684static int swap_idle_threshold2 = 10; 685SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 686 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 687 688/* 689 * Swapout is driven by the pageout daemon. Very simple, we find eligible 690 * procs and unwire their u-areas. We try to always "swap" at least one 691 * process in case we need the room for a swapin. 692 * If any procs have been sleeping/stopped for at least maxslp seconds, 693 * they are swapped. Else, we swap the longest-sleeping or stopped process, 694 * if any, otherwise the longest-resident process. 695 */ 696void 697swapout_procs(action) 698int action; 699{ 700 struct proc *p; 701 struct thread *td; 702 struct ksegrp *kg; 703 int didswap = 0; 704 705 GIANT_REQUIRED; 706 707retry: 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 atomic_add_int(&vm->vm_refcnt, 1); 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 pageout daemon didn't free enough pages, 823 * or if this process is idle and the system is 824 * configured to swap proactively, swap it out. 825 */ 826 if ((action & VM_SWAP_NORMAL) || 827 ((action & VM_SWAP_IDLE) && 828 (minslptime > swap_idle_threshold2))) { 829 swapout(p); 830 didswap++; 831 mtx_unlock_spin(&sched_lock); 832 PROC_UNLOCK(p); 833 vm_map_unlock(&vm->vm_map); 834 vmspace_free(vm); 835 sx_sunlock(&allproc_lock); 836 goto retry; 837 } 838nextproc: 839 mtx_unlock_spin(&sched_lock); 840 } 841nextproc2: 842 PROC_UNLOCK(p); 843 vm_map_unlock(&vm->vm_map); 844nextproc1: 845 vmspace_free(vm); 846 continue; 847 } 848 sx_sunlock(&allproc_lock); 849 /* 850 * If we swapped something out, and another process needed memory, 851 * then wakeup the sched process. 852 */ 853 if (didswap) 854 wakeup(&proc0); 855} 856 857static void 858swapout(p) 859 struct proc *p; 860{ 861 struct thread *td; 862 863 PROC_LOCK_ASSERT(p, MA_OWNED); 864 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 865#if defined(SWAP_DEBUG) 866 printf("swapping out %d\n", p->p_pid); 867#endif 868 869 /* 870 * The states of this process and its threads may have changed 871 * by now. Assuming that there is only one pageout daemon thread, 872 * this process should still be in memory. 873 */ 874 KASSERT((p->p_sflag & (PS_INMEM|PS_SWAPPINGOUT|PS_SWAPPINGIN)) == PS_INMEM, 875 ("swapout: lost a swapout race?")); 876 877#if defined(INVARIANTS) 878 /* 879 * Make sure that all threads are safe to be swapped out. 880 * 881 * Alternatively, we could swap out only safe threads. 882 */ 883 FOREACH_THREAD_IN_PROC(p, td) { 884 KASSERT(thread_safetoswapout(td), 885 ("swapout: there is a thread not safe for swapout")); 886 } 887#endif /* INVARIANTS */ 888 889 ++p->p_stats->p_ru.ru_nswap; 890 /* 891 * remember the process resident count 892 */ 893 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 894 895 p->p_sflag &= ~PS_INMEM; 896 p->p_sflag |= PS_SWAPPINGOUT; 897 PROC_UNLOCK(p); 898 FOREACH_THREAD_IN_PROC(p, td) 899 TD_SET_SWAPPED(td); 900 mtx_unlock_spin(&sched_lock); 901 902 FOREACH_THREAD_IN_PROC(p, td) 903 vm_thread_swapout(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 */ 911