vm_glue.c revision 137910
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 137910 2004-11-20 02:29:00Z 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 94#include <sys/user.h> 95 96extern int maxslp; 97 98/* 99 * System initialization 100 * 101 * Note: proc0 from proc.h 102 */ 103static void vm_init_limits(void *); 104SYSINIT(vm_limits, SI_SUB_VM_CONF, SI_ORDER_FIRST, vm_init_limits, &proc0) 105 106/* 107 * THIS MUST BE THE LAST INITIALIZATION ITEM!!! 108 * 109 * Note: run scheduling should be divorced from the vm system. 110 */ 111static void scheduler(void *); 112SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY, scheduler, NULL) 113 114#ifndef NO_SWAPPING 115static void swapout(struct proc *); 116#endif 117 118/* 119 * MPSAFE 120 * 121 * WARNING! This code calls vm_map_check_protection() which only checks 122 * the associated vm_map_entry range. It does not determine whether the 123 * contents of the memory is actually readable or writable. In most cases 124 * just checking the vm_map_entry is sufficient within the kernel's address 125 * space. 126 */ 127int 128kernacc(addr, len, rw) 129 void *addr; 130 int len, rw; 131{ 132 boolean_t rv; 133 vm_offset_t saddr, eaddr; 134 vm_prot_t prot; 135 136 KASSERT((rw & ~VM_PROT_ALL) == 0, 137 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 138 prot = rw; 139 saddr = trunc_page((vm_offset_t)addr); 140 eaddr = round_page((vm_offset_t)addr + len); 141 vm_map_lock_read(kernel_map); 142 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 143 vm_map_unlock_read(kernel_map); 144 return (rv == TRUE); 145} 146 147/* 148 * MPSAFE 149 * 150 * WARNING! This code calls vm_map_check_protection() which only checks 151 * the associated vm_map_entry range. It does not determine whether the 152 * contents of the memory is actually readable or writable. vmapbuf(), 153 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 154 * used in conjuction with this call. 155 */ 156int 157useracc(addr, len, rw) 158 void *addr; 159 int len, rw; 160{ 161 boolean_t rv; 162 vm_prot_t prot; 163 vm_map_t map; 164 165 KASSERT((rw & ~VM_PROT_ALL) == 0, 166 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 167 prot = rw; 168 map = &curproc->p_vmspace->vm_map; 169 if ((vm_offset_t)addr + len > vm_map_max(map) || 170 (vm_offset_t)addr + len < (vm_offset_t)addr) { 171 return (FALSE); 172 } 173 vm_map_lock_read(map); 174 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 175 round_page((vm_offset_t)addr + len), prot); 176 vm_map_unlock_read(map); 177 return (rv == TRUE); 178} 179 180int 181vslock(void *addr, size_t len) 182{ 183 vm_offset_t end, last, start; 184 vm_size_t npages; 185 int error; 186 187 last = (vm_offset_t)addr + len; 188 start = trunc_page((vm_offset_t)addr); 189 end = round_page(last); 190 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr) 191 return (EINVAL); 192 npages = atop(end - start); 193 if (npages > vm_page_max_wired) 194 return (ENOMEM); 195 PROC_LOCK(curproc); 196 if (ptoa(npages + 197 pmap_wired_count(vm_map_pmap(&curproc->p_vmspace->vm_map))) > 198 lim_cur(curproc, RLIMIT_MEMLOCK)) { 199 PROC_UNLOCK(curproc); 200 return (ENOMEM); 201 } 202 PROC_UNLOCK(curproc); 203#if 0 204 /* 205 * XXX - not yet 206 * 207 * The limit for transient usage of wired pages should be 208 * larger than for "permanent" wired pages (mlock()). 209 * 210 * Also, the sysctl code, which is the only present user 211 * of vslock(), does a hard loop on EAGAIN. 212 */ 213 if (npages + cnt.v_wire_count > vm_page_max_wired) 214 return (EAGAIN); 215#endif 216 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 217 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 218 /* 219 * Return EFAULT on error to match copy{in,out}() behaviour 220 * rather than returning ENOMEM like mlock() would. 221 */ 222 return (error == KERN_SUCCESS ? 0 : EFAULT); 223} 224 225void 226vsunlock(void *addr, size_t len) 227{ 228 229 /* Rely on the parameter sanity checks performed by vslock(). */ 230 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 231 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 232 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 233} 234 235#ifndef KSTACK_MAX_PAGES 236#define KSTACK_MAX_PAGES 32 237#endif 238 239/* 240 * Create the kernel stack (including pcb for i386) for a new thread. 241 * This routine directly affects the fork perf for a process and 242 * create performance for a thread. 243 */ 244void 245vm_thread_new(struct thread *td, int pages) 246{ 247 vm_object_t ksobj; 248 vm_offset_t ks; 249 vm_page_t m, ma[KSTACK_MAX_PAGES]; 250 int i; 251 252 /* Bounds check */ 253 if (pages <= 1) 254 pages = KSTACK_PAGES; 255 else if (pages > KSTACK_MAX_PAGES) 256 pages = KSTACK_MAX_PAGES; 257 /* 258 * Allocate an object for the kstack. 259 */ 260 ksobj = vm_object_allocate(OBJT_DEFAULT, pages); 261 td->td_kstack_obj = ksobj; 262 /* 263 * Get a kernel virtual address for this thread's kstack. 264 */ 265 ks = kmem_alloc_nofault(kernel_map, 266 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 267 if (ks == 0) 268 panic("vm_thread_new: kstack allocation failed"); 269 if (KSTACK_GUARD_PAGES != 0) { 270 pmap_qremove(ks, KSTACK_GUARD_PAGES); 271 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 272 } 273 td->td_kstack = ks; 274 /* 275 * Knowing the number of pages allocated is useful when you 276 * want to deallocate them. 277 */ 278 td->td_kstack_pages = pages; 279 /* 280 * For the length of the stack, link in a real page of ram for each 281 * page of stack. 282 */ 283 VM_OBJECT_LOCK(ksobj); 284 for (i = 0; i < pages; i++) { 285 /* 286 * Get a kernel stack page. 287 */ 288 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 289 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 290 ma[i] = m; 291 m->valid = VM_PAGE_BITS_ALL; 292 } 293 VM_OBJECT_UNLOCK(ksobj); 294 pmap_qenter(ks, ma, pages); 295} 296 297/* 298 * Dispose of a thread's kernel stack. 299 */ 300void 301vm_thread_dispose(struct thread *td) 302{ 303 vm_object_t ksobj; 304 vm_offset_t ks; 305 vm_page_t m; 306 int i, pages; 307 308 pages = td->td_kstack_pages; 309 ksobj = td->td_kstack_obj; 310 ks = td->td_kstack; 311 pmap_qremove(ks, pages); 312 VM_OBJECT_LOCK(ksobj); 313 for (i = 0; i < pages; i++) { 314 m = vm_page_lookup(ksobj, i); 315 if (m == NULL) 316 panic("vm_thread_dispose: kstack already missing?"); 317 vm_page_lock_queues(); 318 vm_page_unwire(m, 0); 319 vm_page_free(m); 320 vm_page_unlock_queues(); 321 } 322 VM_OBJECT_UNLOCK(ksobj); 323 vm_object_deallocate(ksobj); 324 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 325 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 326} 327 328/* 329 * Allow a thread's kernel stack to be paged out. 330 */ 331void 332vm_thread_swapout(struct thread *td) 333{ 334 vm_object_t ksobj; 335 vm_page_t m; 336 int i, pages; 337 338 cpu_thread_swapout(td); 339 pages = td->td_kstack_pages; 340 ksobj = td->td_kstack_obj; 341 pmap_qremove(td->td_kstack, pages); 342 VM_OBJECT_LOCK(ksobj); 343 for (i = 0; i < pages; i++) { 344 m = vm_page_lookup(ksobj, i); 345 if (m == NULL) 346 panic("vm_thread_swapout: kstack already missing?"); 347 vm_page_lock_queues(); 348 vm_page_dirty(m); 349 vm_page_unwire(m, 0); 350 vm_page_unlock_queues(); 351 } 352 VM_OBJECT_UNLOCK(ksobj); 353} 354 355/* 356 * Bring the kernel stack for a specified thread back in. 357 */ 358void 359vm_thread_swapin(struct thread *td) 360{ 361 vm_object_t ksobj; 362 vm_page_t m, ma[KSTACK_MAX_PAGES]; 363 int i, pages, rv; 364 365 pages = td->td_kstack_pages; 366 ksobj = td->td_kstack_obj; 367 VM_OBJECT_LOCK(ksobj); 368 for (i = 0; i < pages; i++) { 369 m = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 370 if (m->valid != VM_PAGE_BITS_ALL) { 371 rv = vm_pager_get_pages(ksobj, &m, 1, 0); 372 if (rv != VM_PAGER_OK) 373 panic("vm_thread_swapin: cannot get kstack for proc: %d", td->td_proc->p_pid); 374 m = vm_page_lookup(ksobj, i); 375 m->valid = VM_PAGE_BITS_ALL; 376 } 377 ma[i] = m; 378 vm_page_lock_queues(); 379 vm_page_wire(m); 380 vm_page_wakeup(m); 381 vm_page_unlock_queues(); 382 } 383 VM_OBJECT_UNLOCK(ksobj); 384 pmap_qenter(td->td_kstack, ma, pages); 385 cpu_thread_swapin(td); 386} 387 388/* 389 * Set up a variable-sized alternate kstack. 390 */ 391void 392vm_thread_new_altkstack(struct thread *td, int pages) 393{ 394 395 td->td_altkstack = td->td_kstack; 396 td->td_altkstack_obj = td->td_kstack_obj; 397 td->td_altkstack_pages = td->td_kstack_pages; 398 399 vm_thread_new(td, pages); 400} 401 402/* 403 * Restore the original kstack. 404 */ 405void 406vm_thread_dispose_altkstack(struct thread *td) 407{ 408 409 vm_thread_dispose(td); 410 411 td->td_kstack = td->td_altkstack; 412 td->td_kstack_obj = td->td_altkstack_obj; 413 td->td_kstack_pages = td->td_altkstack_pages; 414 td->td_altkstack = 0; 415 td->td_altkstack_obj = NULL; 416 td->td_altkstack_pages = 0; 417} 418 419/* 420 * Implement fork's actions on an address space. 421 * Here we arrange for the address space to be copied or referenced, 422 * allocate a user struct (pcb and kernel stack), then call the 423 * machine-dependent layer to fill those in and make the new process 424 * ready to run. The new process is set up so that it returns directly 425 * to user mode to avoid stack copying and relocation problems. 426 */ 427void 428vm_forkproc(td, p2, td2, flags) 429 struct thread *td; 430 struct proc *p2; 431 struct thread *td2; 432 int flags; 433{ 434 struct proc *p1 = td->td_proc; 435 436 if ((flags & RFPROC) == 0) { 437 /* 438 * Divorce the memory, if it is shared, essentially 439 * this changes shared memory amongst threads, into 440 * COW locally. 441 */ 442 if ((flags & RFMEM) == 0) { 443 if (p1->p_vmspace->vm_refcnt > 1) { 444 vmspace_unshare(p1); 445 } 446 } 447 cpu_fork(td, p2, td2, flags); 448 return; 449 } 450 451 if (flags & RFMEM) { 452 p2->p_vmspace = p1->p_vmspace; 453 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 454 } 455 456 while (vm_page_count_severe()) { 457 VM_WAIT; 458 } 459 460 if ((flags & RFMEM) == 0) { 461 p2->p_vmspace = vmspace_fork(p1->p_vmspace); 462 if (p1->p_vmspace->vm_shm) 463 shmfork(p1, p2); 464 } 465 466 /* 467 * cpu_fork will copy and update the pcb, set up the kernel stack, 468 * and make the child ready to run. 469 */ 470 cpu_fork(td, p2, td2, flags); 471} 472 473/* 474 * Called after process has been wait(2)'ed apon and is being reaped. 475 * The idea is to reclaim resources that we could not reclaim while 476 * the process was still executing. 477 */ 478void 479vm_waitproc(p) 480 struct proc *p; 481{ 482 483 vmspace_exitfree(p); /* and clean-out the vmspace */ 484} 485 486/* 487 * Set default limits for VM system. 488 * Called for proc 0, and then inherited by all others. 489 * 490 * XXX should probably act directly on proc0. 491 */ 492static void 493vm_init_limits(udata) 494 void *udata; 495{ 496 struct proc *p = udata; 497 struct plimit *limp; 498 int rss_limit; 499 500 /* 501 * Set up the initial limits on process VM. Set the maximum resident 502 * set size to be half of (reasonably) available memory. Since this 503 * is a soft limit, it comes into effect only when the system is out 504 * of memory - half of main memory helps to favor smaller processes, 505 * and reduces thrashing of the object cache. 506 */ 507 limp = p->p_limit; 508 limp->pl_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 509 limp->pl_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 510 limp->pl_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 511 limp->pl_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 512 /* limit the limit to no less than 2MB */ 513 rss_limit = max(cnt.v_free_count, 512); 514 limp->pl_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 515 limp->pl_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 516} 517 518void 519faultin(p) 520 struct proc *p; 521{ 522#ifdef NO_SWAPPING 523 524 PROC_LOCK_ASSERT(p, MA_OWNED); 525 if ((p->p_sflag & PS_INMEM) == 0) 526 panic("faultin: proc swapped out with NO_SWAPPING!"); 527#else /* !NO_SWAPPING */ 528 struct thread *td; 529 530 GIANT_REQUIRED; 531 PROC_LOCK_ASSERT(p, MA_OWNED); 532 /* 533 * If another process is swapping in this process, 534 * just wait until it finishes. 535 */ 536 if (p->p_sflag & PS_SWAPPINGIN) 537 msleep(&p->p_sflag, &p->p_mtx, PVM, "faultin", 0); 538 else if ((p->p_sflag & PS_INMEM) == 0) { 539 /* 540 * Don't let another thread swap process p out while we are 541 * busy swapping it in. 542 */ 543 ++p->p_lock; 544 mtx_lock_spin(&sched_lock); 545 p->p_sflag |= PS_SWAPPINGIN; 546 mtx_unlock_spin(&sched_lock); 547 PROC_UNLOCK(p); 548 549 FOREACH_THREAD_IN_PROC(p, td) 550 vm_thread_swapin(td); 551 552 PROC_LOCK(p); 553 mtx_lock_spin(&sched_lock); 554 p->p_sflag &= ~PS_SWAPPINGIN; 555 p->p_sflag |= PS_INMEM; 556 FOREACH_THREAD_IN_PROC(p, td) { 557 TD_CLR_SWAPPED(td); 558 if (TD_CAN_RUN(td)) 559 setrunnable(td); 560 } 561 mtx_unlock_spin(&sched_lock); 562 563 wakeup(&p->p_sflag); 564 565 /* Allow other threads to swap p out now. */ 566 --p->p_lock; 567 } 568#endif /* NO_SWAPPING */ 569} 570 571/* 572 * This swapin algorithm attempts to swap-in processes only if there 573 * is enough space for them. Of course, if a process waits for a long 574 * time, it will be swapped in anyway. 575 * 576 * XXXKSE - process with the thread with highest priority counts.. 577 * 578 * Giant is still held at this point, to be released in tsleep. 579 */ 580/* ARGSUSED*/ 581static void 582scheduler(dummy) 583 void *dummy; 584{ 585 struct proc *p; 586 struct thread *td; 587 int pri; 588 struct proc *pp; 589 int ppri; 590 591 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 592 /* GIANT_REQUIRED */ 593 594loop: 595 if (vm_page_count_min()) { 596 VM_WAIT; 597 goto loop; 598 } 599 600 pp = NULL; 601 ppri = INT_MIN; 602 sx_slock(&allproc_lock); 603 FOREACH_PROC_IN_SYSTEM(p) { 604 struct ksegrp *kg; 605 if (p->p_sflag & (PS_INMEM | PS_SWAPPINGOUT | PS_SWAPPINGIN)) { 606 continue; 607 } 608 mtx_lock_spin(&sched_lock); 609 FOREACH_THREAD_IN_PROC(p, td) { 610 /* 611 * An otherwise runnable thread of a process 612 * swapped out has only the TDI_SWAPPED bit set. 613 * 614 */ 615 if (td->td_inhibitors == TDI_SWAPPED) { 616 kg = td->td_ksegrp; 617 pri = p->p_swtime + kg->kg_slptime; 618 if ((p->p_sflag & PS_SWAPINREQ) == 0) { 619 pri -= p->p_nice * 8; 620 } 621 622 /* 623 * if this ksegrp is higher priority 624 * and there is enough space, then select 625 * this process instead of the previous 626 * selection. 627 */ 628 if (pri > ppri) { 629 pp = p; 630 ppri = pri; 631 } 632 } 633 } 634 mtx_unlock_spin(&sched_lock); 635 } 636 sx_sunlock(&allproc_lock); 637 638 /* 639 * Nothing to do, back to sleep. 640 */ 641 if ((p = pp) == NULL) { 642 tsleep(&proc0, PVM, "sched", maxslp * hz / 2); 643 goto loop; 644 } 645 PROC_LOCK(p); 646 647 /* 648 * Another process may be bringing or may have already 649 * brought this process in while we traverse all threads. 650 * Or, this process may even be being swapped out again. 651 */ 652 if (p->p_sflag & (PS_INMEM | PS_SWAPPINGOUT | PS_SWAPPINGIN)) { 653 PROC_UNLOCK(p); 654 goto loop; 655 } 656 657 mtx_lock_spin(&sched_lock); 658 p->p_sflag &= ~PS_SWAPINREQ; 659 mtx_unlock_spin(&sched_lock); 660 661 /* 662 * We would like to bring someone in. (only if there is space). 663 * [What checks the space? ] 664 */ 665 faultin(p); 666 PROC_UNLOCK(p); 667 mtx_lock_spin(&sched_lock); 668 p->p_swtime = 0; 669 mtx_unlock_spin(&sched_lock); 670 goto loop; 671} 672 673#ifndef NO_SWAPPING 674 675/* 676 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 677 */ 678static int swap_idle_threshold1 = 2; 679SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 680 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 681 682/* 683 * Swap_idle_threshold2 is the time that a process can be idle before 684 * it will be swapped out, if idle swapping is enabled. 685 */ 686static int swap_idle_threshold2 = 10; 687SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 688 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 689 690/* 691 * Swapout is driven by the pageout daemon. Very simple, we find eligible 692 * procs and unwire their u-areas. We try to always "swap" at least one 693 * process in case we need the room for a swapin. 694 * If any procs have been sleeping/stopped for at least maxslp seconds, 695 * they are swapped. Else, we swap the longest-sleeping or stopped process, 696 * if any, otherwise the longest-resident process. 697 */ 698void 699swapout_procs(action) 700int action; 701{ 702 struct proc *p; 703 struct thread *td; 704 struct ksegrp *kg; 705 int didswap = 0; 706 707 GIANT_REQUIRED; 708 709retry: 710 sx_slock(&allproc_lock); 711 FOREACH_PROC_IN_SYSTEM(p) { 712 struct vmspace *vm; 713 int minslptime = 100000; 714 715 /* 716 * Watch out for a process in 717 * creation. It may have no 718 * address space or lock yet. 719 */ 720 mtx_lock_spin(&sched_lock); 721 if (p->p_state == PRS_NEW) { 722 mtx_unlock_spin(&sched_lock); 723 continue; 724 } 725 mtx_unlock_spin(&sched_lock); 726 727 /* 728 * An aio daemon switches its 729 * address space while running. 730 * Perform a quick check whether 731 * a process has P_SYSTEM. 732 */ 733 if ((p->p_flag & P_SYSTEM) != 0) 734 continue; 735 736 /* 737 * Do not swapout a process that 738 * is waiting for VM data 739 * structures as there is a possible 740 * deadlock. Test this first as 741 * this may block. 742 * 743 * Lock the map until swapout 744 * finishes, or a thread of this 745 * process may attempt to alter 746 * the map. 747 */ 748 PROC_LOCK(p); 749 vm = p->p_vmspace; 750 KASSERT(vm != NULL, 751 ("swapout_procs: a process has no address space")); 752 atomic_add_int(&vm->vm_refcnt, 1); 753 PROC_UNLOCK(p); 754 if (!vm_map_trylock(&vm->vm_map)) 755 goto nextproc1; 756 757 PROC_LOCK(p); 758 if (p->p_lock != 0 || 759 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 760 ) != 0) { 761 goto nextproc2; 762 } 763 /* 764 * only aiod changes vmspace, however it will be 765 * skipped because of the if statement above checking 766 * for P_SYSTEM 767 */ 768 if ((p->p_sflag & (PS_INMEM|PS_SWAPPINGOUT|PS_SWAPPINGIN)) != PS_INMEM) 769 goto nextproc2; 770 771 switch (p->p_state) { 772 default: 773 /* Don't swap out processes in any sort 774 * of 'special' state. */ 775 break; 776 777 case PRS_NORMAL: 778 mtx_lock_spin(&sched_lock); 779 /* 780 * do not swapout a realtime process 781 * Check all the thread groups.. 782 */ 783 FOREACH_KSEGRP_IN_PROC(p, kg) { 784 if (PRI_IS_REALTIME(kg->kg_pri_class)) 785 goto nextproc; 786 787 /* 788 * Guarantee swap_idle_threshold1 789 * time in memory. 790 */ 791 if (kg->kg_slptime < swap_idle_threshold1) 792 goto nextproc; 793 794 /* 795 * Do not swapout a process if it is 796 * waiting on a critical event of some 797 * kind or there is a thread whose 798 * pageable memory may be accessed. 799 * 800 * This could be refined to support 801 * swapping out a thread. 802 */ 803 FOREACH_THREAD_IN_GROUP(kg, td) { 804 if ((td->td_priority) < PSOCK || 805 !thread_safetoswapout(td)) 806 goto nextproc; 807 } 808 /* 809 * If the system is under memory stress, 810 * or if we are swapping 811 * idle processes >= swap_idle_threshold2, 812 * then swap the process out. 813 */ 814 if (((action & VM_SWAP_NORMAL) == 0) && 815 (((action & VM_SWAP_IDLE) == 0) || 816 (kg->kg_slptime < swap_idle_threshold2))) 817 goto nextproc; 818 819 if (minslptime > kg->kg_slptime) 820 minslptime = kg->kg_slptime; 821 } 822 823 /* 824 * If the pageout daemon didn't free enough pages, 825 * or if this process is idle and the system is 826 * configured to swap proactively, swap it out. 827 */ 828 if ((action & VM_SWAP_NORMAL) || 829 ((action & VM_SWAP_IDLE) && 830 (minslptime > swap_idle_threshold2))) { 831 swapout(p); 832 didswap++; 833 mtx_unlock_spin(&sched_lock); 834 PROC_UNLOCK(p); 835 vm_map_unlock(&vm->vm_map); 836 vmspace_free(vm); 837 sx_sunlock(&allproc_lock); 838 goto retry; 839 } 840nextproc: 841 mtx_unlock_spin(&sched_lock); 842 } 843nextproc2: 844 PROC_UNLOCK(p); 845 vm_map_unlock(&vm->vm_map); 846nextproc1: 847 vmspace_free(vm); 848 continue; 849 } 850 sx_sunlock(&allproc_lock); 851 /* 852 * If we swapped something out, and another process needed memory, 853 * then wakeup the sched process. 854 */ 855 if (didswap) 856 wakeup(&proc0); 857} 858 859static void 860swapout(p) 861 struct proc *p; 862{ 863 struct thread *td; 864 865 PROC_LOCK_ASSERT(p, MA_OWNED); 866 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 867#if defined(SWAP_DEBUG) 868 printf("swapping out %d\n", p->p_pid); 869#endif 870 871 /* 872 * The states of this process and its threads may have changed 873 * by now. Assuming that there is only one pageout daemon thread, 874 * this process should still be in memory. 875 */ 876 KASSERT((p->p_sflag & (PS_INMEM|PS_SWAPPINGOUT|PS_SWAPPINGIN)) == PS_INMEM, 877 ("swapout: lost a swapout race?")); 878 879#if defined(INVARIANTS) 880 /* 881 * Make sure that all threads are safe to be swapped out. 882 * 883 * Alternatively, we could swap out only safe threads. 884 */ 885 FOREACH_THREAD_IN_PROC(p, td) { 886 KASSERT(thread_safetoswapout(td), 887 ("swapout: there is a thread not safe for swapout")); 888 } 889#endif /* INVARIANTS */ 890 891 ++p->p_stats->p_ru.ru_nswap; 892 /* 893 * remember the process resident count 894 */ 895 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 896 897 p->p_sflag &= ~PS_INMEM; 898 p->p_sflag |= PS_SWAPPINGOUT; 899 PROC_UNLOCK(p); 900 FOREACH_THREAD_IN_PROC(p, td) 901 TD_SET_SWAPPED(td); 902 mtx_unlock_spin(&sched_lock); 903 904 FOREACH_THREAD_IN_PROC(p, td) 905 vm_thread_swapout(td); 906 907 PROC_LOCK(p); 908 mtx_lock_spin(&sched_lock); 909 p->p_sflag &= ~PS_SWAPPINGOUT; 910 p->p_swtime = 0; 911} 912#endif /* !NO_SWAPPING */ 913