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: releng/8.0/sys/vm/vm_glue.c 196977 2009-09-08 15:31:23Z kib $"); 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/sched.h> 74 #include <sys/sf_buf.h> 75 #include <sys/shm.h> 76 #include <sys/vmmeter.h> 77 #include <sys/sx.h> 78 #include <sys/sysctl.h> 79 80 #include <sys/eventhandler.h> 81 #include <sys/kernel.h> 82 #include <sys/ktr.h> 83 #include <sys/unistd.h> 84 85 #include <vm/vm.h> 86 #include <vm/vm_param.h> 87 #include <vm/pmap.h> 88 #include <vm/vm_map.h> 89 #include <vm/vm_page.h> 90 #include <vm/vm_pageout.h> 91 #include <vm/vm_object.h> 92 #include <vm/vm_kern.h> 93 #include <vm/vm_extern.h> 94 #include <vm/vm_pager.h> 95 #include <vm/swap_pager.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_ANY, scheduler, NULL); 114 115 #ifndef NO_SWAPPING 116 static int swapout(struct proc *); 117 static void swapclear(struct proc *); 118 #endif 119 120 /* 121 * MPSAFE 122 * 123 * WARNING! This code calls vm_map_check_protection() which only checks 124 * the associated vm_map_entry range. It does not determine whether the 125 * contents of the memory is actually readable or writable. In most cases 126 * just checking the vm_map_entry is sufficient within the kernel's address 127 * space. 128 */ 129 int 130 kernacc(addr, len, rw) 131 void *addr; 132 int len, rw; 133 { 134 boolean_t rv; 135 vm_offset_t saddr, eaddr; 136 vm_prot_t prot; 137 138 KASSERT((rw & ~VM_PROT_ALL) == 0, 139 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 140 141 if ((vm_offset_t)addr + len > kernel_map->max_offset || 142 (vm_offset_t)addr + len < (vm_offset_t)addr) 143 return (FALSE); 144 145 prot = rw; 146 saddr = trunc_page((vm_offset_t)addr); 147 eaddr = round_page((vm_offset_t)addr + len); 148 vm_map_lock_read(kernel_map); 149 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 150 vm_map_unlock_read(kernel_map); 151 return (rv == TRUE); 152 } 153 154 /* 155 * MPSAFE 156 * 157 * WARNING! This code calls vm_map_check_protection() which only checks 158 * the associated vm_map_entry range. It does not determine whether the 159 * contents of the memory is actually readable or writable. vmapbuf(), 160 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 161 * used in conjuction with this call. 162 */ 163 int 164 useracc(addr, len, rw) 165 void *addr; 166 int len, rw; 167 { 168 boolean_t rv; 169 vm_prot_t prot; 170 vm_map_t map; 171 172 KASSERT((rw & ~VM_PROT_ALL) == 0, 173 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 174 prot = rw; 175 map = &curproc->p_vmspace->vm_map; 176 if ((vm_offset_t)addr + len > vm_map_max(map) || 177 (vm_offset_t)addr + len < (vm_offset_t)addr) { 178 return (FALSE); 179 } 180 vm_map_lock_read(map); 181 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 182 round_page((vm_offset_t)addr + len), prot); 183 vm_map_unlock_read(map); 184 return (rv == TRUE); 185 } 186 187 int 188 vslock(void *addr, size_t len) 189 { 190 vm_offset_t end, last, start; 191 vm_size_t npages; 192 int error; 193 194 last = (vm_offset_t)addr + len; 195 start = trunc_page((vm_offset_t)addr); 196 end = round_page(last); 197 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr) 198 return (EINVAL); 199 npages = atop(end - start); 200 if (npages > vm_page_max_wired) 201 return (ENOMEM); 202 PROC_LOCK(curproc); 203 if (ptoa(npages + 204 pmap_wired_count(vm_map_pmap(&curproc->p_vmspace->vm_map))) > 205 lim_cur(curproc, RLIMIT_MEMLOCK)) { 206 PROC_UNLOCK(curproc); 207 return (ENOMEM); 208 } 209 PROC_UNLOCK(curproc); 210 #if 0 211 /* 212 * XXX - not yet 213 * 214 * The limit for transient usage of wired pages should be 215 * larger than for "permanent" wired pages (mlock()). 216 * 217 * Also, the sysctl code, which is the only present user 218 * of vslock(), does a hard loop on EAGAIN. 219 */ 220 if (npages + cnt.v_wire_count > vm_page_max_wired) 221 return (EAGAIN); 222 #endif 223 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 224 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 225 /* 226 * Return EFAULT on error to match copy{in,out}() behaviour 227 * rather than returning ENOMEM like mlock() would. 228 */ 229 return (error == KERN_SUCCESS ? 0 : EFAULT); 230 } 231 232 void 233 vsunlock(void *addr, size_t len) 234 { 235 236 /* Rely on the parameter sanity checks performed by vslock(). */ 237 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 238 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 239 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 240 } 241 242 /* 243 * Pin the page contained within the given object at the given offset. If the 244 * page is not resident, allocate and load it using the given object's pager. 245 * Return the pinned page if successful; otherwise, return NULL. 246 */ 247 static vm_page_t 248 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset) 249 { 250 vm_page_t m, ma[1]; 251 vm_pindex_t pindex; 252 int rv; 253 254 VM_OBJECT_LOCK(object); 255 pindex = OFF_TO_IDX(offset); 256 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 257 if (m->valid != VM_PAGE_BITS_ALL) { 258 ma[0] = m; 259 rv = vm_pager_get_pages(object, ma, 1, 0); 260 m = vm_page_lookup(object, pindex); 261 if (m == NULL) 262 goto out; 263 if (rv != VM_PAGER_OK) { 264 vm_page_lock_queues(); 265 vm_page_free(m); 266 vm_page_unlock_queues(); 267 m = NULL; 268 goto out; 269 } 270 } 271 vm_page_lock_queues(); 272 vm_page_hold(m); 273 vm_page_unlock_queues(); 274 vm_page_wakeup(m); 275 out: 276 VM_OBJECT_UNLOCK(object); 277 return (m); 278 } 279 280 /* 281 * Return a CPU private mapping to the page at the given offset within the 282 * given object. The page is pinned before it is mapped. 283 */ 284 struct sf_buf * 285 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset) 286 { 287 vm_page_t m; 288 289 m = vm_imgact_hold_page(object, offset); 290 if (m == NULL) 291 return (NULL); 292 sched_pin(); 293 return (sf_buf_alloc(m, SFB_CPUPRIVATE)); 294 } 295 296 /* 297 * Destroy the given CPU private mapping and unpin the page that it mapped. 298 */ 299 void 300 vm_imgact_unmap_page(struct sf_buf *sf) 301 { 302 vm_page_t m; 303 304 m = sf_buf_page(sf); 305 sf_buf_free(sf); 306 sched_unpin(); 307 vm_page_lock_queues(); 308 vm_page_unhold(m); 309 vm_page_unlock_queues(); 310 } 311 312 struct kstack_cache_entry { 313 vm_object_t ksobj; 314 struct kstack_cache_entry *next_ks_entry; 315 }; 316 317 static struct kstack_cache_entry *kstack_cache; 318 static int kstack_cache_size = 128; 319 static int kstacks; 320 static struct mtx kstack_cache_mtx; 321 SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0, 322 ""); 323 SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0, 324 ""); 325 326 #ifndef KSTACK_MAX_PAGES 327 #define KSTACK_MAX_PAGES 32 328 #endif 329 330 /* 331 * Create the kernel stack (including pcb for i386) for a new thread. 332 * This routine directly affects the fork perf for a process and 333 * create performance for a thread. 334 */ 335 int 336 vm_thread_new(struct thread *td, int pages) 337 { 338 vm_object_t ksobj; 339 vm_offset_t ks; 340 vm_page_t m, ma[KSTACK_MAX_PAGES]; 341 struct kstack_cache_entry *ks_ce; 342 int i; 343 344 /* Bounds check */ 345 if (pages <= 1) 346 pages = KSTACK_PAGES; 347 else if (pages > KSTACK_MAX_PAGES) 348 pages = KSTACK_MAX_PAGES; 349 350 if (pages == KSTACK_PAGES) { 351 mtx_lock(&kstack_cache_mtx); 352 if (kstack_cache != NULL) { 353 ks_ce = kstack_cache; 354 kstack_cache = ks_ce->next_ks_entry; 355 mtx_unlock(&kstack_cache_mtx); 356 357 td->td_kstack_obj = ks_ce->ksobj; 358 td->td_kstack = (vm_offset_t)ks_ce; 359 td->td_kstack_pages = KSTACK_PAGES; 360 return (1); 361 } 362 mtx_unlock(&kstack_cache_mtx); 363 } 364 365 /* 366 * Allocate an object for the kstack. 367 */ 368 ksobj = vm_object_allocate(OBJT_DEFAULT, pages); 369 370 /* 371 * Get a kernel virtual address for this thread's kstack. 372 */ 373 ks = kmem_alloc_nofault(kernel_map, 374 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 375 if (ks == 0) { 376 printf("vm_thread_new: kstack allocation failed\n"); 377 vm_object_deallocate(ksobj); 378 return (0); 379 } 380 381 atomic_add_int(&kstacks, 1); 382 if (KSTACK_GUARD_PAGES != 0) { 383 pmap_qremove(ks, KSTACK_GUARD_PAGES); 384 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 385 } 386 td->td_kstack_obj = ksobj; 387 td->td_kstack = ks; 388 /* 389 * Knowing the number of pages allocated is useful when you 390 * want to deallocate them. 391 */ 392 td->td_kstack_pages = pages; 393 /* 394 * For the length of the stack, link in a real page of ram for each 395 * page of stack. 396 */ 397 VM_OBJECT_LOCK(ksobj); 398 for (i = 0; i < pages; i++) { 399 /* 400 * Get a kernel stack page. 401 */ 402 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 403 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 404 ma[i] = m; 405 m->valid = VM_PAGE_BITS_ALL; 406 } 407 VM_OBJECT_UNLOCK(ksobj); 408 pmap_qenter(ks, ma, pages); 409 return (1); 410 } 411 412 static void 413 vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages) 414 { 415 vm_page_t m; 416 int i; 417 418 atomic_add_int(&kstacks, -1); 419 pmap_qremove(ks, pages); 420 VM_OBJECT_LOCK(ksobj); 421 for (i = 0; i < pages; i++) { 422 m = vm_page_lookup(ksobj, i); 423 if (m == NULL) 424 panic("vm_thread_dispose: kstack already missing?"); 425 vm_page_lock_queues(); 426 vm_page_unwire(m, 0); 427 vm_page_free(m); 428 vm_page_unlock_queues(); 429 } 430 VM_OBJECT_UNLOCK(ksobj); 431 vm_object_deallocate(ksobj); 432 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 433 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 434 } 435 436 /* 437 * Dispose of a thread's kernel stack. 438 */ 439 void 440 vm_thread_dispose(struct thread *td) 441 { 442 vm_object_t ksobj; 443 vm_offset_t ks; 444 struct kstack_cache_entry *ks_ce; 445 int pages; 446 447 pages = td->td_kstack_pages; 448 ksobj = td->td_kstack_obj; 449 ks = td->td_kstack; 450 td->td_kstack = 0; 451 td->td_kstack_pages = 0; 452 if (pages == KSTACK_PAGES && kstacks <= kstack_cache_size) { 453 ks_ce = (struct kstack_cache_entry *)ks; 454 ks_ce->ksobj = ksobj; 455 mtx_lock(&kstack_cache_mtx); 456 ks_ce->next_ks_entry = kstack_cache; 457 kstack_cache = ks_ce; 458 mtx_unlock(&kstack_cache_mtx); 459 return; 460 } 461 vm_thread_stack_dispose(ksobj, ks, pages); 462 } 463 464 static void 465 vm_thread_stack_lowmem(void *nulll) 466 { 467 struct kstack_cache_entry *ks_ce, *ks_ce1; 468 469 mtx_lock(&kstack_cache_mtx); 470 ks_ce = kstack_cache; 471 kstack_cache = NULL; 472 mtx_unlock(&kstack_cache_mtx); 473 474 while (ks_ce != NULL) { 475 ks_ce1 = ks_ce; 476 ks_ce = ks_ce->next_ks_entry; 477 478 vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1, 479 KSTACK_PAGES); 480 } 481 } 482 483 static void 484 kstack_cache_init(void *nulll) 485 { 486 487 EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL, 488 EVENTHANDLER_PRI_ANY); 489 } 490 491 MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF); 492 SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL); 493 494 /* 495 * Allow a thread's kernel stack to be paged out. 496 */ 497 void 498 vm_thread_swapout(struct thread *td) 499 { 500 vm_object_t ksobj; 501 vm_page_t m; 502 int i, pages; 503 504 cpu_thread_swapout(td); 505 pages = td->td_kstack_pages; 506 ksobj = td->td_kstack_obj; 507 pmap_qremove(td->td_kstack, pages); 508 VM_OBJECT_LOCK(ksobj); 509 for (i = 0; i < pages; i++) { 510 m = vm_page_lookup(ksobj, i); 511 if (m == NULL) 512 panic("vm_thread_swapout: kstack already missing?"); 513 vm_page_lock_queues(); 514 vm_page_dirty(m); 515 vm_page_unwire(m, 0); 516 vm_page_unlock_queues(); 517 } 518 VM_OBJECT_UNLOCK(ksobj); 519 } 520 521 /* 522 * Bring the kernel stack for a specified thread back in. 523 */ 524 void 525 vm_thread_swapin(struct thread *td) 526 { 527 vm_object_t ksobj; 528 vm_page_t m, ma[KSTACK_MAX_PAGES]; 529 int i, pages, rv; 530 531 pages = td->td_kstack_pages; 532 ksobj = td->td_kstack_obj; 533 VM_OBJECT_LOCK(ksobj); 534 for (i = 0; i < pages; i++) { 535 m = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 536 if (m->valid != VM_PAGE_BITS_ALL) { 537 rv = vm_pager_get_pages(ksobj, &m, 1, 0); 538 if (rv != VM_PAGER_OK) 539 panic("vm_thread_swapin: cannot get kstack for proc: %d", td->td_proc->p_pid); 540 m = vm_page_lookup(ksobj, i); 541 } 542 ma[i] = m; 543 vm_page_lock_queues(); 544 vm_page_wire(m); 545 vm_page_unlock_queues(); 546 vm_page_wakeup(m); 547 } 548 VM_OBJECT_UNLOCK(ksobj); 549 pmap_qenter(td->td_kstack, ma, pages); 550 cpu_thread_swapin(td); 551 } 552 553 /* 554 * Implement fork's actions on an address space. 555 * Here we arrange for the address space to be copied or referenced, 556 * allocate a user struct (pcb and kernel stack), then call the 557 * machine-dependent layer to fill those in and make the new process 558 * ready to run. The new process is set up so that it returns directly 559 * to user mode to avoid stack copying and relocation problems. 560 */ 561 int 562 vm_forkproc(td, p2, td2, vm2, flags) 563 struct thread *td; 564 struct proc *p2; 565 struct thread *td2; 566 struct vmspace *vm2; 567 int flags; 568 { 569 struct proc *p1 = td->td_proc; 570 int error; 571 572 if ((flags & RFPROC) == 0) { 573 /* 574 * Divorce the memory, if it is shared, essentially 575 * this changes shared memory amongst threads, into 576 * COW locally. 577 */ 578 if ((flags & RFMEM) == 0) { 579 if (p1->p_vmspace->vm_refcnt > 1) { 580 error = vmspace_unshare(p1); 581 if (error) 582 return (error); 583 } 584 } 585 cpu_fork(td, p2, td2, flags); 586 return (0); 587 } 588 589 if (flags & RFMEM) { 590 p2->p_vmspace = p1->p_vmspace; 591 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 592 } 593 594 while (vm_page_count_severe()) { 595 VM_WAIT; 596 } 597 598 if ((flags & RFMEM) == 0) { 599 p2->p_vmspace = vm2; 600 if (p1->p_vmspace->vm_shm) 601 shmfork(p1, p2); 602 } 603 604 /* 605 * cpu_fork will copy and update the pcb, set up the kernel stack, 606 * and make the child ready to run. 607 */ 608 cpu_fork(td, p2, td2, flags); 609 return (0); 610 } 611 612 /* 613 * Called after process has been wait(2)'ed apon and is being reaped. 614 * The idea is to reclaim resources that we could not reclaim while 615 * the process was still executing. 616 */ 617 void 618 vm_waitproc(p) 619 struct proc *p; 620 { 621 622 vmspace_exitfree(p); /* and clean-out the vmspace */ 623 } 624 625 /* 626 * Set default limits for VM system. 627 * Called for proc 0, and then inherited by all others. 628 * 629 * XXX should probably act directly on proc0. 630 */ 631 static void 632 vm_init_limits(udata) 633 void *udata; 634 { 635 struct proc *p = udata; 636 struct plimit *limp; 637 int rss_limit; 638 639 /* 640 * Set up the initial limits on process VM. Set the maximum resident 641 * set size to be half of (reasonably) available memory. Since this 642 * is a soft limit, it comes into effect only when the system is out 643 * of memory - half of main memory helps to favor smaller processes, 644 * and reduces thrashing of the object cache. 645 */ 646 limp = p->p_limit; 647 limp->pl_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 648 limp->pl_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 649 limp->pl_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 650 limp->pl_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 651 /* limit the limit to no less than 2MB */ 652 rss_limit = max(cnt.v_free_count, 512); 653 limp->pl_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 654 limp->pl_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 655 } 656 657 void 658 faultin(p) 659 struct proc *p; 660 { 661 #ifdef NO_SWAPPING 662 663 PROC_LOCK_ASSERT(p, MA_OWNED); 664 if ((p->p_flag & P_INMEM) == 0) 665 panic("faultin: proc swapped out with NO_SWAPPING!"); 666 #else /* !NO_SWAPPING */ 667 struct thread *td; 668 669 PROC_LOCK_ASSERT(p, MA_OWNED); 670 /* 671 * If another process is swapping in this process, 672 * just wait until it finishes. 673 */ 674 if (p->p_flag & P_SWAPPINGIN) { 675 while (p->p_flag & P_SWAPPINGIN) 676 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 677 return; 678 } 679 if ((p->p_flag & P_INMEM) == 0) { 680 /* 681 * Don't let another thread swap process p out while we are 682 * busy swapping it in. 683 */ 684 ++p->p_lock; 685 p->p_flag |= P_SWAPPINGIN; 686 PROC_UNLOCK(p); 687 688 /* 689 * We hold no lock here because the list of threads 690 * can not change while all threads in the process are 691 * swapped out. 692 */ 693 FOREACH_THREAD_IN_PROC(p, td) 694 vm_thread_swapin(td); 695 PROC_LOCK(p); 696 swapclear(p); 697 p->p_swtick = ticks; 698 699 wakeup(&p->p_flag); 700 701 /* Allow other threads to swap p out now. */ 702 --p->p_lock; 703 } 704 #endif /* NO_SWAPPING */ 705 } 706 707 /* 708 * This swapin algorithm attempts to swap-in processes only if there 709 * is enough space for them. Of course, if a process waits for a long 710 * time, it will be swapped in anyway. 711 * 712 * Giant is held on entry. 713 */ 714 /* ARGSUSED*/ 715 static void 716 scheduler(dummy) 717 void *dummy; 718 { 719 struct proc *p; 720 struct thread *td; 721 struct proc *pp; 722 int slptime; 723 int swtime; 724 int ppri; 725 int pri; 726 727 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 728 mtx_unlock(&Giant); 729 730 loop: 731 if (vm_page_count_min()) { 732 VM_WAIT; 733 goto loop; 734 } 735 736 pp = NULL; 737 ppri = INT_MIN; 738 sx_slock(&allproc_lock); 739 FOREACH_PROC_IN_SYSTEM(p) { 740 PROC_LOCK(p); 741 if (p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { 742 PROC_UNLOCK(p); 743 continue; 744 } 745 swtime = (ticks - p->p_swtick) / hz; 746 FOREACH_THREAD_IN_PROC(p, td) { 747 /* 748 * An otherwise runnable thread of a process 749 * swapped out has only the TDI_SWAPPED bit set. 750 * 751 */ 752 thread_lock(td); 753 if (td->td_inhibitors == TDI_SWAPPED) { 754 slptime = (ticks - td->td_slptick) / hz; 755 pri = swtime + slptime; 756 if ((td->td_flags & TDF_SWAPINREQ) == 0) 757 pri -= p->p_nice * 8; 758 /* 759 * if this thread is higher priority 760 * and there is enough space, then select 761 * this process instead of the previous 762 * selection. 763 */ 764 if (pri > ppri) { 765 pp = p; 766 ppri = pri; 767 } 768 } 769 thread_unlock(td); 770 } 771 PROC_UNLOCK(p); 772 } 773 sx_sunlock(&allproc_lock); 774 775 /* 776 * Nothing to do, back to sleep. 777 */ 778 if ((p = pp) == NULL) { 779 tsleep(&proc0, PVM, "sched", maxslp * hz / 2); 780 goto loop; 781 } 782 PROC_LOCK(p); 783 784 /* 785 * Another process may be bringing or may have already 786 * brought this process in while we traverse all threads. 787 * Or, this process may even be being swapped out again. 788 */ 789 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { 790 PROC_UNLOCK(p); 791 goto loop; 792 } 793 794 /* 795 * We would like to bring someone in. (only if there is space). 796 * [What checks the space? ] 797 */ 798 faultin(p); 799 PROC_UNLOCK(p); 800 goto loop; 801 } 802 803 void 804 kick_proc0(void) 805 { 806 807 wakeup(&proc0); 808 } 809 810 #ifndef NO_SWAPPING 811 812 /* 813 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 814 */ 815 static int swap_idle_threshold1 = 2; 816 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 817 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 818 819 /* 820 * Swap_idle_threshold2 is the time that a process can be idle before 821 * it will be swapped out, if idle swapping is enabled. 822 */ 823 static int swap_idle_threshold2 = 10; 824 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 825 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 826 827 /* 828 * Swapout is driven by the pageout daemon. Very simple, we find eligible 829 * procs and swap out their stacks. We try to always "swap" at least one 830 * process in case we need the room for a swapin. 831 * If any procs have been sleeping/stopped for at least maxslp seconds, 832 * they are swapped. Else, we swap the longest-sleeping or stopped process, 833 * if any, otherwise the longest-resident process. 834 */ 835 void 836 swapout_procs(action) 837 int action; 838 { 839 struct proc *p; 840 struct thread *td; 841 int didswap = 0; 842 843 retry: 844 sx_slock(&allproc_lock); 845 FOREACH_PROC_IN_SYSTEM(p) { 846 struct vmspace *vm; 847 int minslptime = 100000; 848 int slptime; 849 850 /* 851 * Watch out for a process in 852 * creation. It may have no 853 * address space or lock yet. 854 */ 855 if (p->p_state == PRS_NEW) 856 continue; 857 /* 858 * An aio daemon switches its 859 * address space while running. 860 * Perform a quick check whether 861 * a process has P_SYSTEM. 862 */ 863 if ((p->p_flag & P_SYSTEM) != 0) 864 continue; 865 /* 866 * Do not swapout a process that 867 * is waiting for VM data 868 * structures as there is a possible 869 * deadlock. Test this first as 870 * this may block. 871 * 872 * Lock the map until swapout 873 * finishes, or a thread of this 874 * process may attempt to alter 875 * the map. 876 */ 877 vm = vmspace_acquire_ref(p); 878 if (vm == NULL) 879 continue; 880 if (!vm_map_trylock(&vm->vm_map)) 881 goto nextproc1; 882 883 PROC_LOCK(p); 884 if (p->p_lock != 0 || 885 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 886 ) != 0) { 887 goto nextproc; 888 } 889 /* 890 * only aiod changes vmspace, however it will be 891 * skipped because of the if statement above checking 892 * for P_SYSTEM 893 */ 894 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM) 895 goto nextproc; 896 897 switch (p->p_state) { 898 default: 899 /* Don't swap out processes in any sort 900 * of 'special' state. */ 901 break; 902 903 case PRS_NORMAL: 904 /* 905 * do not swapout a realtime process 906 * Check all the thread groups.. 907 */ 908 FOREACH_THREAD_IN_PROC(p, td) { 909 thread_lock(td); 910 if (PRI_IS_REALTIME(td->td_pri_class)) { 911 thread_unlock(td); 912 goto nextproc; 913 } 914 slptime = (ticks - td->td_slptick) / hz; 915 /* 916 * Guarantee swap_idle_threshold1 917 * time in memory. 918 */ 919 if (slptime < swap_idle_threshold1) { 920 thread_unlock(td); 921 goto nextproc; 922 } 923 924 /* 925 * Do not swapout a process if it is 926 * waiting on a critical event of some 927 * kind or there is a thread whose 928 * pageable memory may be accessed. 929 * 930 * This could be refined to support 931 * swapping out a thread. 932 */ 933 if (!thread_safetoswapout(td)) { 934 thread_unlock(td); 935 goto nextproc; 936 } 937 /* 938 * If the system is under memory stress, 939 * or if we are swapping 940 * idle processes >= swap_idle_threshold2, 941 * then swap the process out. 942 */ 943 if (((action & VM_SWAP_NORMAL) == 0) && 944 (((action & VM_SWAP_IDLE) == 0) || 945 (slptime < swap_idle_threshold2))) { 946 thread_unlock(td); 947 goto nextproc; 948 } 949 950 if (minslptime > slptime) 951 minslptime = slptime; 952 thread_unlock(td); 953 } 954 955 /* 956 * If the pageout daemon didn't free enough pages, 957 * or if this process is idle and the system is 958 * configured to swap proactively, swap it out. 959 */ 960 if ((action & VM_SWAP_NORMAL) || 961 ((action & VM_SWAP_IDLE) && 962 (minslptime > swap_idle_threshold2))) { 963 if (swapout(p) == 0) 964 didswap++; 965 PROC_UNLOCK(p); 966 vm_map_unlock(&vm->vm_map); 967 vmspace_free(vm); 968 sx_sunlock(&allproc_lock); 969 goto retry; 970 } 971 } 972 nextproc: 973 PROC_UNLOCK(p); 974 vm_map_unlock(&vm->vm_map); 975 nextproc1: 976 vmspace_free(vm); 977 continue; 978 } 979 sx_sunlock(&allproc_lock); 980 /* 981 * If we swapped something out, and another process needed memory, 982 * then wakeup the sched process. 983 */ 984 if (didswap) 985 wakeup(&proc0); 986 } 987 988 static void 989 swapclear(p) 990 struct proc *p; 991 { 992 struct thread *td; 993 994 PROC_LOCK_ASSERT(p, MA_OWNED); 995 996 FOREACH_THREAD_IN_PROC(p, td) { 997 thread_lock(td); 998 td->td_flags |= TDF_INMEM; 999 td->td_flags &= ~TDF_SWAPINREQ; 1000 TD_CLR_SWAPPED(td); 1001 if (TD_CAN_RUN(td)) 1002 if (setrunnable(td)) { 1003 #ifdef INVARIANTS 1004 /* 1005 * XXX: We just cleared TDI_SWAPPED 1006 * above and set TDF_INMEM, so this 1007 * should never happen. 1008 */ 1009 panic("not waking up swapper"); 1010 #endif 1011 } 1012 thread_unlock(td); 1013 } 1014 p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT); 1015 p->p_flag |= P_INMEM; 1016 } 1017 1018 static int 1019 swapout(p) 1020 struct proc *p; 1021 { 1022 struct thread *td; 1023 1024 PROC_LOCK_ASSERT(p, MA_OWNED); 1025 #if defined(SWAP_DEBUG) 1026 printf("swapping out %d\n", p->p_pid); 1027 #endif 1028 1029 /* 1030 * The states of this process and its threads may have changed 1031 * by now. Assuming that there is only one pageout daemon thread, 1032 * this process should still be in memory. 1033 */ 1034 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM, 1035 ("swapout: lost a swapout race?")); 1036 1037 /* 1038 * remember the process resident count 1039 */ 1040 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 1041 /* 1042 * Check and mark all threads before we proceed. 1043 */ 1044 p->p_flag &= ~P_INMEM; 1045 p->p_flag |= P_SWAPPINGOUT; 1046 FOREACH_THREAD_IN_PROC(p, td) { 1047 thread_lock(td); 1048 if (!thread_safetoswapout(td)) { 1049 thread_unlock(td); 1050 swapclear(p); 1051 return (EBUSY); 1052 } 1053 td->td_flags &= ~TDF_INMEM; 1054 TD_SET_SWAPPED(td); 1055 thread_unlock(td); 1056 } 1057 td = FIRST_THREAD_IN_PROC(p); 1058 ++td->td_ru.ru_nswap; 1059 PROC_UNLOCK(p); 1060 1061 /* 1062 * This list is stable because all threads are now prevented from 1063 * running. The list is only modified in the context of a running 1064 * thread in this process. 1065 */ 1066 FOREACH_THREAD_IN_PROC(p, td) 1067 vm_thread_swapout(td); 1068 1069 PROC_LOCK(p); 1070 p->p_flag &= ~P_SWAPPINGOUT; 1071 p->p_swtick = ticks; 1072 return (0); 1073 } 1074 #endif /* !NO_SWAPPING */
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