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 * 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: src/sys/vm/vm_glue.c,v 1.202.2.5 2005/02/23 06:41:44 alc Exp $"); 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 extern int maxslp; 95 96 /* 97 * System initialization 98 * 99 * Note: proc0 from proc.h 100 */ 101 static void vm_init_limits(void *); 102 SYSINIT(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 */ 109 static void scheduler(void *); 110 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY, scheduler, NULL) 111 112 #ifndef NO_SWAPPING 113 static 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 */ 125 int 126 kernacc(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)); 136 137 if ((vm_offset_t)addr + len > kernel_map->max_offset || 138 (vm_offset_t)addr + len < (vm_offset_t)addr) 139 return (FALSE); 140 141 prot = rw; 142 saddr = trunc_page((vm_offset_t)addr); 143 eaddr = round_page((vm_offset_t)addr + len); 144 vm_map_lock_read(kernel_map); 145 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 146 vm_map_unlock_read(kernel_map); 147 return (rv == TRUE); 148 } 149 150 /* 151 * MPSAFE 152 * 153 * WARNING! This code calls vm_map_check_protection() which only checks 154 * the associated vm_map_entry range. It does not determine whether the 155 * contents of the memory is actually readable or writable. vmapbuf(), 156 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 157 * used in conjuction with this call. 158 */ 159 int 160 useracc(addr, len, rw) 161 void *addr; 162 int len, rw; 163 { 164 boolean_t rv; 165 vm_prot_t prot; 166 vm_map_t map; 167 168 KASSERT((rw & ~VM_PROT_ALL) == 0, 169 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 170 prot = rw; 171 map = &curproc->p_vmspace->vm_map; 172 if ((vm_offset_t)addr + len > vm_map_max(map) || 173 (vm_offset_t)addr + len < (vm_offset_t)addr) { 174 return (FALSE); 175 } 176 vm_map_lock_read(map); 177 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 178 round_page((vm_offset_t)addr + len), prot); 179 vm_map_unlock_read(map); 180 return (rv == TRUE); 181 } 182 183 int 184 vslock(void *addr, size_t len) 185 { 186 vm_offset_t end, last, start; 187 vm_size_t npages; 188 int error; 189 190 last = (vm_offset_t)addr + len; 191 start = trunc_page((vm_offset_t)addr); 192 end = round_page(last); 193 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr) 194 return (EINVAL); 195 npages = atop(end - start); 196 if (npages > vm_page_max_wired) 197 return (ENOMEM); 198 PROC_LOCK(curproc); 199 if (ptoa(npages + 200 pmap_wired_count(vm_map_pmap(&curproc->p_vmspace->vm_map))) > 201 lim_cur(curproc, RLIMIT_MEMLOCK)) { 202 PROC_UNLOCK(curproc); 203 return (ENOMEM); 204 } 205 PROC_UNLOCK(curproc); 206 #if 0 207 /* 208 * XXX - not yet 209 * 210 * The limit for transient usage of wired pages should be 211 * larger than for "permanent" wired pages (mlock()). 212 * 213 * Also, the sysctl code, which is the only present user 214 * of vslock(), does a hard loop on EAGAIN. 215 */ 216 if (npages + cnt.v_wire_count > vm_page_max_wired) 217 return (EAGAIN); 218 #endif 219 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 220 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 221 /* 222 * Return EFAULT on error to match copy{in,out}() behaviour 223 * rather than returning ENOMEM like mlock() would. 224 */ 225 return (error == KERN_SUCCESS ? 0 : EFAULT); 226 } 227 228 void 229 vsunlock(void *addr, size_t len) 230 { 231 232 /* Rely on the parameter sanity checks performed by vslock(). */ 233 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 234 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 235 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 236 } 237 238 #ifndef KSTACK_MAX_PAGES 239 #define KSTACK_MAX_PAGES 32 240 #endif 241 242 /* 243 * Create the kernel stack (including pcb for i386) for a new thread. 244 * This routine directly affects the fork perf for a process and 245 * create performance for a thread. 246 */ 247 void 248 vm_thread_new(struct thread *td, int pages) 249 { 250 vm_object_t ksobj; 251 vm_offset_t ks; 252 vm_page_t m, ma[KSTACK_MAX_PAGES]; 253 int i; 254 255 /* Bounds check */ 256 if (pages <= 1) 257 pages = KSTACK_PAGES; 258 else if (pages > KSTACK_MAX_PAGES) 259 pages = KSTACK_MAX_PAGES; 260 /* 261 * Allocate an object for the kstack. 262 */ 263 ksobj = vm_object_allocate(OBJT_DEFAULT, pages); 264 td->td_kstack_obj = ksobj; 265 /* 266 * Get a kernel virtual address for this thread's kstack. 267 */ 268 ks = kmem_alloc_nofault(kernel_map, 269 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 270 if (ks == 0) 271 panic("vm_thread_new: kstack allocation failed"); 272 if (KSTACK_GUARD_PAGES != 0) { 273 pmap_qremove(ks, KSTACK_GUARD_PAGES); 274 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 275 } 276 td->td_kstack = ks; 277 /* 278 * Knowing the number of pages allocated is useful when you 279 * want to deallocate them. 280 */ 281 td->td_kstack_pages = pages; 282 /* 283 * For the length of the stack, link in a real page of ram for each 284 * page of stack. 285 */ 286 VM_OBJECT_LOCK(ksobj); 287 for (i = 0; i < pages; i++) { 288 /* 289 * Get a kernel stack page. 290 */ 291 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 292 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 293 ma[i] = m; 294 m->valid = VM_PAGE_BITS_ALL; 295 } 296 VM_OBJECT_UNLOCK(ksobj); 297 pmap_qenter(ks, ma, pages); 298 } 299 300 /* 301 * Dispose of a thread's kernel stack. 302 */ 303 void 304 vm_thread_dispose(struct thread *td) 305 { 306 vm_object_t ksobj; 307 vm_offset_t ks; 308 vm_page_t m; 309 int i, pages; 310 311 pages = td->td_kstack_pages; 312 ksobj = td->td_kstack_obj; 313 ks = td->td_kstack; 314 pmap_qremove(ks, pages); 315 VM_OBJECT_LOCK(ksobj); 316 for (i = 0; i < pages; i++) { 317 m = vm_page_lookup(ksobj, i); 318 if (m == NULL) 319 panic("vm_thread_dispose: kstack already missing?"); 320 vm_page_lock_queues(); 321 vm_page_unwire(m, 0); 322 vm_page_free(m); 323 vm_page_unlock_queues(); 324 } 325 VM_OBJECT_UNLOCK(ksobj); 326 vm_object_deallocate(ksobj); 327 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 328 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 329 } 330 331 /* 332 * Allow a thread's kernel stack to be paged out. 333 */ 334 void 335 vm_thread_swapout(struct thread *td) 336 { 337 vm_object_t ksobj; 338 vm_page_t m; 339 int i, pages; 340 341 cpu_thread_swapout(td); 342 pages = td->td_kstack_pages; 343 ksobj = td->td_kstack_obj; 344 pmap_qremove(td->td_kstack, pages); 345 VM_OBJECT_LOCK(ksobj); 346 for (i = 0; i < pages; i++) { 347 m = vm_page_lookup(ksobj, i); 348 if (m == NULL) 349 panic("vm_thread_swapout: kstack already missing?"); 350 vm_page_lock_queues(); 351 vm_page_dirty(m); 352 vm_page_unwire(m, 0); 353 vm_page_unlock_queues(); 354 } 355 VM_OBJECT_UNLOCK(ksobj); 356 } 357 358 /* 359 * Bring the kernel stack for a specified thread back in. 360 */ 361 void 362 vm_thread_swapin(struct thread *td) 363 { 364 vm_object_t ksobj; 365 vm_page_t m, ma[KSTACK_MAX_PAGES]; 366 int i, pages, rv; 367 368 pages = td->td_kstack_pages; 369 ksobj = td->td_kstack_obj; 370 VM_OBJECT_LOCK(ksobj); 371 for (i = 0; i < pages; i++) { 372 m = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 373 if (m->valid != VM_PAGE_BITS_ALL) { 374 rv = vm_pager_get_pages(ksobj, &m, 1, 0); 375 if (rv != VM_PAGER_OK) 376 panic("vm_thread_swapin: cannot get kstack for proc: %d", td->td_proc->p_pid); 377 m = vm_page_lookup(ksobj, i); 378 m->valid = VM_PAGE_BITS_ALL; 379 } 380 ma[i] = m; 381 vm_page_lock_queues(); 382 vm_page_wire(m); 383 vm_page_wakeup(m); 384 vm_page_unlock_queues(); 385 } 386 VM_OBJECT_UNLOCK(ksobj); 387 pmap_qenter(td->td_kstack, ma, pages); 388 cpu_thread_swapin(td); 389 } 390 391 /* 392 * Set up a variable-sized alternate kstack. 393 */ 394 void 395 vm_thread_new_altkstack(struct thread *td, int pages) 396 { 397 398 td->td_altkstack = td->td_kstack; 399 td->td_altkstack_obj = td->td_kstack_obj; 400 td->td_altkstack_pages = td->td_kstack_pages; 401 402 vm_thread_new(td, pages); 403 } 404 405 /* 406 * Restore the original kstack. 407 */ 408 void 409 vm_thread_dispose_altkstack(struct thread *td) 410 { 411 412 vm_thread_dispose(td); 413 414 td->td_kstack = td->td_altkstack; 415 td->td_kstack_obj = td->td_altkstack_obj; 416 td->td_kstack_pages = td->td_altkstack_pages; 417 td->td_altkstack = 0; 418 td->td_altkstack_obj = NULL; 419 td->td_altkstack_pages = 0; 420 } 421 422 /* 423 * Implement fork's actions on an address space. 424 * Here we arrange for the address space to be copied or referenced, 425 * allocate a user struct (pcb and kernel stack), then call the 426 * machine-dependent layer to fill those in and make the new process 427 * ready to run. The new process is set up so that it returns directly 428 * to user mode to avoid stack copying and relocation problems. 429 */ 430 void 431 vm_forkproc(td, p2, td2, flags) 432 struct thread *td; 433 struct proc *p2; 434 struct thread *td2; 435 int flags; 436 { 437 struct proc *p1 = td->td_proc; 438 439 if ((flags & RFPROC) == 0) { 440 /* 441 * Divorce the memory, if it is shared, essentially 442 * this changes shared memory amongst threads, into 443 * COW locally. 444 */ 445 if ((flags & RFMEM) == 0) { 446 if (p1->p_vmspace->vm_refcnt > 1) { 447 vmspace_unshare(p1); 448 } 449 } 450 cpu_fork(td, p2, td2, flags); 451 return; 452 } 453 454 if (flags & RFMEM) { 455 p2->p_vmspace = p1->p_vmspace; 456 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 457 } 458 459 while (vm_page_count_severe()) { 460 VM_WAIT; 461 } 462 463 if ((flags & RFMEM) == 0) { 464 p2->p_vmspace = vmspace_fork(p1->p_vmspace); 465 if (p1->p_vmspace->vm_shm) 466 shmfork(p1, p2); 467 } 468 469 /* 470 * cpu_fork will copy and update the pcb, set up the kernel stack, 471 * and make the child ready to run. 472 */ 473 cpu_fork(td, p2, td2, flags); 474 } 475 476 /* 477 * Called after process has been wait(2)'ed apon and is being reaped. 478 * The idea is to reclaim resources that we could not reclaim while 479 * the process was still executing. 480 */ 481 void 482 vm_waitproc(p) 483 struct proc *p; 484 { 485 486 vmspace_exitfree(p); /* and clean-out the vmspace */ 487 } 488 489 /* 490 * Set default limits for VM system. 491 * Called for proc 0, and then inherited by all others. 492 * 493 * XXX should probably act directly on proc0. 494 */ 495 static void 496 vm_init_limits(udata) 497 void *udata; 498 { 499 struct proc *p = udata; 500 struct plimit *limp; 501 int rss_limit; 502 503 /* 504 * Set up the initial limits on process VM. Set the maximum resident 505 * set size to be half of (reasonably) available memory. Since this 506 * is a soft limit, it comes into effect only when the system is out 507 * of memory - half of main memory helps to favor smaller processes, 508 * and reduces thrashing of the object cache. 509 */ 510 limp = p->p_limit; 511 limp->pl_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 512 limp->pl_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 513 limp->pl_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 514 limp->pl_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 515 /* limit the limit to no less than 2MB */ 516 rss_limit = max(cnt.v_free_count, 512); 517 limp->pl_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 518 limp->pl_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 519 } 520 521 void 522 faultin(p) 523 struct proc *p; 524 { 525 #ifdef NO_SWAPPING 526 527 PROC_LOCK_ASSERT(p, MA_OWNED); 528 if ((p->p_sflag & PS_INMEM) == 0) 529 panic("faultin: proc swapped out with NO_SWAPPING!"); 530 #else /* !NO_SWAPPING */ 531 struct thread *td; 532 533 GIANT_REQUIRED; 534 PROC_LOCK_ASSERT(p, MA_OWNED); 535 /* 536 * If another process is swapping in this process, 537 * just wait until it finishes. 538 */ 539 if (p->p_sflag & PS_SWAPPINGIN) 540 msleep(&p->p_sflag, &p->p_mtx, PVM, "faultin", 0); 541 else if ((p->p_sflag & PS_INMEM) == 0) { 542 /* 543 * Don't let another thread swap process p out while we are 544 * busy swapping it in. 545 */ 546 ++p->p_lock; 547 mtx_lock_spin(&sched_lock); 548 p->p_sflag |= PS_SWAPPINGIN; 549 mtx_unlock_spin(&sched_lock); 550 PROC_UNLOCK(p); 551 552 FOREACH_THREAD_IN_PROC(p, td) 553 vm_thread_swapin(td); 554 555 PROC_LOCK(p); 556 mtx_lock_spin(&sched_lock); 557 p->p_sflag &= ~PS_SWAPPINGIN; 558 p->p_sflag |= PS_INMEM; 559 FOREACH_THREAD_IN_PROC(p, td) { 560 TD_CLR_SWAPPED(td); 561 if (TD_CAN_RUN(td)) 562 setrunnable(td); 563 } 564 mtx_unlock_spin(&sched_lock); 565 566 wakeup(&p->p_sflag); 567 568 /* Allow other threads to swap p out now. */ 569 --p->p_lock; 570 } 571 #endif /* NO_SWAPPING */ 572 } 573 574 /* 575 * This swapin algorithm attempts to swap-in processes only if there 576 * is enough space for them. Of course, if a process waits for a long 577 * time, it will be swapped in anyway. 578 * 579 * XXXKSE - process with the thread with highest priority counts.. 580 * 581 * Giant is still held at this point, to be released in tsleep. 582 */ 583 /* ARGSUSED*/ 584 static void 585 scheduler(dummy) 586 void *dummy; 587 { 588 struct proc *p; 589 struct thread *td; 590 int pri; 591 struct proc *pp; 592 int ppri; 593 594 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 595 /* GIANT_REQUIRED */ 596 597 loop: 598 if (vm_page_count_min()) { 599 VM_WAIT; 600 goto loop; 601 } 602 603 pp = NULL; 604 ppri = INT_MIN; 605 sx_slock(&allproc_lock); 606 FOREACH_PROC_IN_SYSTEM(p) { 607 struct ksegrp *kg; 608 if (p->p_sflag & (PS_INMEM | PS_SWAPPINGOUT | PS_SWAPPINGIN)) { 609 continue; 610 } 611 mtx_lock_spin(&sched_lock); 612 FOREACH_THREAD_IN_PROC(p, td) { 613 /* 614 * An otherwise runnable thread of a process 615 * swapped out has only the TDI_SWAPPED bit set. 616 * 617 */ 618 if (td->td_inhibitors == TDI_SWAPPED) { 619 kg = td->td_ksegrp; 620 pri = p->p_swtime + kg->kg_slptime; 621 if ((p->p_sflag & PS_SWAPINREQ) == 0) { 622 pri -= p->p_nice * 8; 623 } 624 625 /* 626 * if this ksegrp is higher priority 627 * and there is enough space, then select 628 * this process instead of the previous 629 * selection. 630 */ 631 if (pri > ppri) { 632 pp = p; 633 ppri = pri; 634 } 635 } 636 } 637 mtx_unlock_spin(&sched_lock); 638 } 639 sx_sunlock(&allproc_lock); 640 641 /* 642 * Nothing to do, back to sleep. 643 */ 644 if ((p = pp) == NULL) { 645 tsleep(&proc0, PVM, "sched", maxslp * hz / 2); 646 goto loop; 647 } 648 PROC_LOCK(p); 649 650 /* 651 * Another process may be bringing or may have already 652 * brought this process in while we traverse all threads. 653 * Or, this process may even be being swapped out again. 654 */ 655 if (p->p_sflag & (PS_INMEM | PS_SWAPPINGOUT | PS_SWAPPINGIN)) { 656 PROC_UNLOCK(p); 657 goto loop; 658 } 659 660 mtx_lock_spin(&sched_lock); 661 p->p_sflag &= ~PS_SWAPINREQ; 662 mtx_unlock_spin(&sched_lock); 663 664 /* 665 * We would like to bring someone in. (only if there is space). 666 * [What checks the space? ] 667 */ 668 faultin(p); 669 PROC_UNLOCK(p); 670 mtx_lock_spin(&sched_lock); 671 p->p_swtime = 0; 672 mtx_unlock_spin(&sched_lock); 673 goto loop; 674 } 675 676 #ifndef NO_SWAPPING 677 678 /* 679 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 680 */ 681 static int swap_idle_threshold1 = 2; 682 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 683 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 684 685 /* 686 * Swap_idle_threshold2 is the time that a process can be idle before 687 * it will be swapped out, if idle swapping is enabled. 688 */ 689 static int swap_idle_threshold2 = 10; 690 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 691 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 692 693 /* 694 * Swapout is driven by the pageout daemon. Very simple, we find eligible 695 * procs and unwire their u-areas. We try to always "swap" at least one 696 * process in case we need the room for a swapin. 697 * If any procs have been sleeping/stopped for at least maxslp seconds, 698 * they are swapped. Else, we swap the longest-sleeping or stopped process, 699 * if any, otherwise the longest-resident process. 700 */ 701 void 702 swapout_procs(action) 703 int action; 704 { 705 struct proc *p; 706 struct thread *td; 707 struct ksegrp *kg; 708 int didswap = 0; 709 710 GIANT_REQUIRED; 711 712 retry: 713 sx_slock(&allproc_lock); 714 FOREACH_PROC_IN_SYSTEM(p) { 715 struct vmspace *vm; 716 int minslptime = 100000; 717 718 /* 719 * Watch out for a process in 720 * creation. It may have no 721 * address space or lock yet. 722 */ 723 mtx_lock_spin(&sched_lock); 724 if (p->p_state == PRS_NEW) { 725 mtx_unlock_spin(&sched_lock); 726 continue; 727 } 728 mtx_unlock_spin(&sched_lock); 729 730 /* 731 * An aio daemon switches its 732 * address space while running. 733 * Perform a quick check whether 734 * a process has P_SYSTEM. 735 */ 736 if ((p->p_flag & P_SYSTEM) != 0) 737 continue; 738 739 /* 740 * Do not swapout a process that 741 * is waiting for VM data 742 * structures as there is a possible 743 * deadlock. Test this first as 744 * this may block. 745 * 746 * Lock the map until swapout 747 * finishes, or a thread of this 748 * process may attempt to alter 749 * the map. 750 */ 751 PROC_LOCK(p); 752 vm = p->p_vmspace; 753 KASSERT(vm != NULL, 754 ("swapout_procs: a process has no address space")); 755 atomic_add_int(&vm->vm_refcnt, 1); 756 PROC_UNLOCK(p); 757 if (!vm_map_trylock(&vm->vm_map)) 758 goto nextproc1; 759 760 PROC_LOCK(p); 761 if (p->p_lock != 0 || 762 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 763 ) != 0) { 764 goto nextproc2; 765 } 766 /* 767 * only aiod changes vmspace, however it will be 768 * skipped because of the if statement above checking 769 * for P_SYSTEM 770 */ 771 if ((p->p_sflag & (PS_INMEM|PS_SWAPPINGOUT|PS_SWAPPINGIN)) != PS_INMEM) 772 goto nextproc2; 773 774 switch (p->p_state) { 775 default: 776 /* Don't swap out processes in any sort 777 * of 'special' state. */ 778 break; 779 780 case PRS_NORMAL: 781 mtx_lock_spin(&sched_lock); 782 /* 783 * do not swapout a realtime process 784 * Check all the thread groups.. 785 */ 786 FOREACH_KSEGRP_IN_PROC(p, kg) { 787 if (PRI_IS_REALTIME(kg->kg_pri_class)) 788 goto nextproc; 789 790 /* 791 * Guarantee swap_idle_threshold1 792 * time in memory. 793 */ 794 if (kg->kg_slptime < swap_idle_threshold1) 795 goto nextproc; 796 797 /* 798 * Do not swapout a process if it is 799 * waiting on a critical event of some 800 * kind or there is a thread whose 801 * pageable memory may be accessed. 802 * 803 * This could be refined to support 804 * swapping out a thread. 805 */ 806 FOREACH_THREAD_IN_GROUP(kg, td) { 807 if ((td->td_priority) < PSOCK || 808 !thread_safetoswapout(td)) 809 goto nextproc; 810 } 811 /* 812 * If the system is under memory stress, 813 * or if we are swapping 814 * idle processes >= swap_idle_threshold2, 815 * then swap the process out. 816 */ 817 if (((action & VM_SWAP_NORMAL) == 0) && 818 (((action & VM_SWAP_IDLE) == 0) || 819 (kg->kg_slptime < swap_idle_threshold2))) 820 goto nextproc; 821 822 if (minslptime > kg->kg_slptime) 823 minslptime = kg->kg_slptime; 824 } 825 826 /* 827 * If the pageout daemon didn't free enough pages, 828 * or if this process is idle and the system is 829 * configured to swap proactively, swap it out. 830 */ 831 if ((action & VM_SWAP_NORMAL) || 832 ((action & VM_SWAP_IDLE) && 833 (minslptime > swap_idle_threshold2))) { 834 swapout(p); 835 didswap++; 836 mtx_unlock_spin(&sched_lock); 837 PROC_UNLOCK(p); 838 vm_map_unlock(&vm->vm_map); 839 vmspace_free(vm); 840 sx_sunlock(&allproc_lock); 841 goto retry; 842 } 843 nextproc: 844 mtx_unlock_spin(&sched_lock); 845 } 846 nextproc2: 847 PROC_UNLOCK(p); 848 vm_map_unlock(&vm->vm_map); 849 nextproc1: 850 vmspace_free(vm); 851 continue; 852 } 853 sx_sunlock(&allproc_lock); 854 /* 855 * If we swapped something out, and another process needed memory, 856 * then wakeup the sched process. 857 */ 858 if (didswap) 859 wakeup(&proc0); 860 } 861 862 static void 863 swapout(p) 864 struct proc *p; 865 { 866 struct thread *td; 867 868 PROC_LOCK_ASSERT(p, MA_OWNED); 869 mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); 870 #if defined(SWAP_DEBUG) 871 printf("swapping out %d\n", p->p_pid); 872 #endif 873 874 /* 875 * The states of this process and its threads may have changed 876 * by now. Assuming that there is only one pageout daemon thread, 877 * this process should still be in memory. 878 */ 879 KASSERT((p->p_sflag & (PS_INMEM|PS_SWAPPINGOUT|PS_SWAPPINGIN)) == PS_INMEM, 880 ("swapout: lost a swapout race?")); 881 882 #if defined(INVARIANTS) 883 /* 884 * Make sure that all threads are safe to be swapped out. 885 * 886 * Alternatively, we could swap out only safe threads. 887 */ 888 FOREACH_THREAD_IN_PROC(p, td) { 889 KASSERT(thread_safetoswapout(td), 890 ("swapout: there is a thread not safe for swapout")); 891 } 892 #endif /* INVARIANTS */ 893 894 ++p->p_stats->p_ru.ru_nswap; 895 /* 896 * remember the process resident count 897 */ 898 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 899 900 p->p_sflag &= ~PS_INMEM; 901 p->p_sflag |= PS_SWAPPINGOUT; 902 PROC_UNLOCK(p); 903 FOREACH_THREAD_IN_PROC(p, td) 904 TD_SET_SWAPPED(td); 905 mtx_unlock_spin(&sched_lock); 906 907 FOREACH_THREAD_IN_PROC(p, td) 908 vm_thread_swapout(td); 909 910 PROC_LOCK(p); 911 mtx_lock_spin(&sched_lock); 912 p->p_sflag &= ~PS_SWAPPINGOUT; 913 p->p_swtime = 0; 914 } 915 #endif /* !NO_SWAPPING */
Cache object: 2b1c5ba281c905f444bd8b49588bf1ca
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