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("$FreeBSD$"); 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/kernel.h> 81 #include <sys/ktr.h> 82 #include <sys/unistd.h> 83 84 #include <vm/vm.h> 85 #include <vm/vm_param.h> 86 #include <vm/pmap.h> 87 #include <vm/vm_map.h> 88 #include <vm/vm_page.h> 89 #include <vm/vm_pageout.h> 90 #include <vm/vm_object.h> 91 #include <vm/vm_kern.h> 92 #include <vm/vm_extern.h> 93 #include <vm/vm_pager.h> 94 #include <vm/swap_pager.h> 95 96 extern int maxslp; 97 98 /* 99 * System initialization 100 * 101 * Note: proc0 from proc.h 102 */ 103 static void vm_init_limits(void *); 104 SYSINIT(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 */ 111 static void scheduler(void *); 112 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY, scheduler, NULL); 113 114 #ifndef NO_SWAPPING 115 static int swapout(struct proc *); 116 static void swapclear(struct proc *); 117 #endif 118 119 /* 120 * MPSAFE 121 * 122 * WARNING! This code calls vm_map_check_protection() which only checks 123 * the associated vm_map_entry range. It does not determine whether the 124 * contents of the memory is actually readable or writable. In most cases 125 * just checking the vm_map_entry is sufficient within the kernel's address 126 * space. 127 */ 128 int 129 kernacc(addr, len, rw) 130 void *addr; 131 int len, rw; 132 { 133 boolean_t rv; 134 vm_offset_t saddr, eaddr; 135 vm_prot_t prot; 136 137 KASSERT((rw & ~VM_PROT_ALL) == 0, 138 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 139 140 if ((vm_offset_t)addr + len > kernel_map->max_offset || 141 (vm_offset_t)addr + len < (vm_offset_t)addr) 142 return (FALSE); 143 144 prot = rw; 145 saddr = trunc_page((vm_offset_t)addr); 146 eaddr = round_page((vm_offset_t)addr + len); 147 vm_map_lock_read(kernel_map); 148 rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot); 149 vm_map_unlock_read(kernel_map); 150 return (rv == TRUE); 151 } 152 153 /* 154 * MPSAFE 155 * 156 * WARNING! This code calls vm_map_check_protection() which only checks 157 * the associated vm_map_entry range. It does not determine whether the 158 * contents of the memory is actually readable or writable. vmapbuf(), 159 * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be 160 * used in conjuction with this call. 161 */ 162 int 163 useracc(addr, len, rw) 164 void *addr; 165 int len, rw; 166 { 167 boolean_t rv; 168 vm_prot_t prot; 169 vm_map_t map; 170 171 KASSERT((rw & ~VM_PROT_ALL) == 0, 172 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 173 prot = rw; 174 map = &curproc->p_vmspace->vm_map; 175 if ((vm_offset_t)addr + len > vm_map_max(map) || 176 (vm_offset_t)addr + len < (vm_offset_t)addr) { 177 return (FALSE); 178 } 179 vm_map_lock_read(map); 180 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 181 round_page((vm_offset_t)addr + len), prot); 182 vm_map_unlock_read(map); 183 return (rv == TRUE); 184 } 185 186 int 187 vslock(void *addr, size_t len) 188 { 189 vm_offset_t end, last, start; 190 vm_size_t npages; 191 int error; 192 193 last = (vm_offset_t)addr + len; 194 start = trunc_page((vm_offset_t)addr); 195 end = round_page(last); 196 if (last < (vm_offset_t)addr || end < (vm_offset_t)addr) 197 return (EINVAL); 198 npages = atop(end - start); 199 if (npages > vm_page_max_wired) 200 return (ENOMEM); 201 PROC_LOCK(curproc); 202 if (ptoa(npages + 203 pmap_wired_count(vm_map_pmap(&curproc->p_vmspace->vm_map))) > 204 lim_cur(curproc, RLIMIT_MEMLOCK)) { 205 PROC_UNLOCK(curproc); 206 return (ENOMEM); 207 } 208 PROC_UNLOCK(curproc); 209 #if 0 210 /* 211 * XXX - not yet 212 * 213 * The limit for transient usage of wired pages should be 214 * larger than for "permanent" wired pages (mlock()). 215 * 216 * Also, the sysctl code, which is the only present user 217 * of vslock(), does a hard loop on EAGAIN. 218 */ 219 if (npages + cnt.v_wire_count > vm_page_max_wired) 220 return (EAGAIN); 221 #endif 222 error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end, 223 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 224 /* 225 * Return EFAULT on error to match copy{in,out}() behaviour 226 * rather than returning ENOMEM like mlock() would. 227 */ 228 return (error == KERN_SUCCESS ? 0 : EFAULT); 229 } 230 231 void 232 vsunlock(void *addr, size_t len) 233 { 234 235 /* Rely on the parameter sanity checks performed by vslock(). */ 236 (void)vm_map_unwire(&curproc->p_vmspace->vm_map, 237 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), 238 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 239 } 240 241 /* 242 * Pin the page contained within the given object at the given offset. If the 243 * page is not resident, allocate and load it using the given object's pager. 244 * Return the pinned page if successful; otherwise, return NULL. 245 */ 246 static vm_page_t 247 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset) 248 { 249 vm_page_t m, ma[1]; 250 vm_pindex_t pindex; 251 int rv; 252 253 VM_OBJECT_LOCK(object); 254 pindex = OFF_TO_IDX(offset); 255 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 256 if (m->valid != VM_PAGE_BITS_ALL) { 257 ma[0] = m; 258 rv = vm_pager_get_pages(object, ma, 1, 0); 259 m = vm_page_lookup(object, pindex); 260 if (m == NULL) 261 goto out; 262 if (rv != VM_PAGER_OK) { 263 vm_page_lock_queues(); 264 vm_page_free(m); 265 vm_page_unlock_queues(); 266 m = NULL; 267 goto out; 268 } 269 } 270 vm_page_lock_queues(); 271 vm_page_hold(m); 272 vm_page_unlock_queues(); 273 vm_page_wakeup(m); 274 out: 275 VM_OBJECT_UNLOCK(object); 276 return (m); 277 } 278 279 /* 280 * Return a CPU private mapping to the page at the given offset within the 281 * given object. The page is pinned before it is mapped. 282 */ 283 struct sf_buf * 284 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset) 285 { 286 vm_page_t m; 287 288 m = vm_imgact_hold_page(object, offset); 289 if (m == NULL) 290 return (NULL); 291 sched_pin(); 292 return (sf_buf_alloc(m, SFB_CPUPRIVATE)); 293 } 294 295 /* 296 * Destroy the given CPU private mapping and unpin the page that it mapped. 297 */ 298 void 299 vm_imgact_unmap_page(struct sf_buf *sf) 300 { 301 vm_page_t m; 302 303 m = sf_buf_page(sf); 304 sf_buf_free(sf); 305 sched_unpin(); 306 vm_page_lock_queues(); 307 vm_page_unhold(m); 308 vm_page_unlock_queues(); 309 } 310 311 #ifndef KSTACK_MAX_PAGES 312 #define KSTACK_MAX_PAGES 32 313 #endif 314 315 /* 316 * Create the kernel stack (including pcb for i386) for a new thread. 317 * This routine directly affects the fork perf for a process and 318 * create performance for a thread. 319 */ 320 int 321 vm_thread_new(struct thread *td, int pages) 322 { 323 vm_object_t ksobj; 324 vm_offset_t ks; 325 vm_page_t m, ma[KSTACK_MAX_PAGES]; 326 int i; 327 328 /* Bounds check */ 329 if (pages <= 1) 330 pages = KSTACK_PAGES; 331 else if (pages > KSTACK_MAX_PAGES) 332 pages = KSTACK_MAX_PAGES; 333 /* 334 * Allocate an object for the kstack. 335 */ 336 ksobj = vm_object_allocate(OBJT_DEFAULT, pages); 337 338 /* 339 * Get a kernel virtual address for this thread's kstack. 340 */ 341 ks = kmem_alloc_nofault(kernel_map, 342 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 343 if (ks == 0) { 344 printf("vm_thread_new: kstack allocation failed\n"); 345 vm_object_deallocate(ksobj); 346 return (0); 347 } 348 349 if (KSTACK_GUARD_PAGES != 0) { 350 pmap_qremove(ks, KSTACK_GUARD_PAGES); 351 ks += KSTACK_GUARD_PAGES * PAGE_SIZE; 352 } 353 td->td_kstack_obj = ksobj; 354 td->td_kstack = ks; 355 /* 356 * Knowing the number of pages allocated is useful when you 357 * want to deallocate them. 358 */ 359 td->td_kstack_pages = pages; 360 /* 361 * For the length of the stack, link in a real page of ram for each 362 * page of stack. 363 */ 364 VM_OBJECT_LOCK(ksobj); 365 for (i = 0; i < pages; i++) { 366 /* 367 * Get a kernel stack page. 368 */ 369 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY | 370 VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED); 371 ma[i] = m; 372 m->valid = VM_PAGE_BITS_ALL; 373 } 374 VM_OBJECT_UNLOCK(ksobj); 375 pmap_qenter(ks, ma, pages); 376 return (1); 377 } 378 379 /* 380 * Dispose of a thread's kernel stack. 381 */ 382 void 383 vm_thread_dispose(struct thread *td) 384 { 385 vm_object_t ksobj; 386 vm_offset_t ks; 387 vm_page_t m; 388 int i, pages; 389 390 pages = td->td_kstack_pages; 391 ksobj = td->td_kstack_obj; 392 ks = td->td_kstack; 393 pmap_qremove(ks, pages); 394 VM_OBJECT_LOCK(ksobj); 395 for (i = 0; i < pages; i++) { 396 m = vm_page_lookup(ksobj, i); 397 if (m == NULL) 398 panic("vm_thread_dispose: kstack already missing?"); 399 vm_page_lock_queues(); 400 vm_page_unwire(m, 0); 401 vm_page_free(m); 402 vm_page_unlock_queues(); 403 } 404 VM_OBJECT_UNLOCK(ksobj); 405 vm_object_deallocate(ksobj); 406 kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE), 407 (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE); 408 td->td_kstack = 0; 409 } 410 411 /* 412 * Allow a thread's kernel stack to be paged out. 413 */ 414 void 415 vm_thread_swapout(struct thread *td) 416 { 417 vm_object_t ksobj; 418 vm_page_t m; 419 int i, pages; 420 421 cpu_thread_swapout(td); 422 pages = td->td_kstack_pages; 423 ksobj = td->td_kstack_obj; 424 pmap_qremove(td->td_kstack, pages); 425 VM_OBJECT_LOCK(ksobj); 426 for (i = 0; i < pages; i++) { 427 m = vm_page_lookup(ksobj, i); 428 if (m == NULL) 429 panic("vm_thread_swapout: kstack already missing?"); 430 vm_page_lock_queues(); 431 vm_page_dirty(m); 432 vm_page_unwire(m, 0); 433 vm_page_unlock_queues(); 434 } 435 VM_OBJECT_UNLOCK(ksobj); 436 } 437 438 /* 439 * Bring the kernel stack for a specified thread back in. 440 */ 441 void 442 vm_thread_swapin(struct thread *td) 443 { 444 vm_object_t ksobj; 445 vm_page_t m, ma[KSTACK_MAX_PAGES]; 446 int i, pages, rv; 447 448 pages = td->td_kstack_pages; 449 ksobj = td->td_kstack_obj; 450 VM_OBJECT_LOCK(ksobj); 451 for (i = 0; i < pages; i++) { 452 m = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 453 if (m->valid != VM_PAGE_BITS_ALL) { 454 rv = vm_pager_get_pages(ksobj, &m, 1, 0); 455 if (rv != VM_PAGER_OK) 456 panic("vm_thread_swapin: cannot get kstack for proc: %d", td->td_proc->p_pid); 457 m = vm_page_lookup(ksobj, i); 458 } 459 ma[i] = m; 460 vm_page_lock_queues(); 461 vm_page_wire(m); 462 vm_page_unlock_queues(); 463 vm_page_wakeup(m); 464 } 465 VM_OBJECT_UNLOCK(ksobj); 466 pmap_qenter(td->td_kstack, ma, pages); 467 cpu_thread_swapin(td); 468 } 469 470 /* 471 * Set up a variable-sized alternate kstack. 472 */ 473 int 474 vm_thread_new_altkstack(struct thread *td, int pages) 475 { 476 477 td->td_altkstack = td->td_kstack; 478 td->td_altkstack_obj = td->td_kstack_obj; 479 td->td_altkstack_pages = td->td_kstack_pages; 480 481 return (vm_thread_new(td, pages)); 482 } 483 484 /* 485 * Restore the original kstack. 486 */ 487 void 488 vm_thread_dispose_altkstack(struct thread *td) 489 { 490 491 vm_thread_dispose(td); 492 493 td->td_kstack = td->td_altkstack; 494 td->td_kstack_obj = td->td_altkstack_obj; 495 td->td_kstack_pages = td->td_altkstack_pages; 496 td->td_altkstack = 0; 497 td->td_altkstack_obj = NULL; 498 td->td_altkstack_pages = 0; 499 } 500 501 /* 502 * Implement fork's actions on an address space. 503 * Here we arrange for the address space to be copied or referenced, 504 * allocate a user struct (pcb and kernel stack), then call the 505 * machine-dependent layer to fill those in and make the new process 506 * ready to run. The new process is set up so that it returns directly 507 * to user mode to avoid stack copying and relocation problems. 508 */ 509 int 510 vm_forkproc(td, p2, td2, vm2, flags) 511 struct thread *td; 512 struct proc *p2; 513 struct thread *td2; 514 struct vmspace *vm2; 515 int flags; 516 { 517 struct proc *p1 = td->td_proc; 518 int error; 519 520 if ((flags & RFPROC) == 0) { 521 /* 522 * Divorce the memory, if it is shared, essentially 523 * this changes shared memory amongst threads, into 524 * COW locally. 525 */ 526 if ((flags & RFMEM) == 0) { 527 if (p1->p_vmspace->vm_refcnt > 1) { 528 error = vmspace_unshare(p1); 529 if (error) 530 return (error); 531 } 532 } 533 cpu_fork(td, p2, td2, flags); 534 return (0); 535 } 536 537 if (flags & RFMEM) { 538 p2->p_vmspace = p1->p_vmspace; 539 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1); 540 } 541 542 while (vm_page_count_severe()) { 543 VM_WAIT; 544 } 545 546 if ((flags & RFMEM) == 0) { 547 p2->p_vmspace = vm2; 548 if (p1->p_vmspace->vm_shm) 549 shmfork(p1, p2); 550 } 551 552 /* 553 * cpu_fork will copy and update the pcb, set up the kernel stack, 554 * and make the child ready to run. 555 */ 556 cpu_fork(td, p2, td2, flags); 557 return (0); 558 } 559 560 /* 561 * Called after process has been wait(2)'ed apon and is being reaped. 562 * The idea is to reclaim resources that we could not reclaim while 563 * the process was still executing. 564 */ 565 void 566 vm_waitproc(p) 567 struct proc *p; 568 { 569 570 vmspace_exitfree(p); /* and clean-out the vmspace */ 571 } 572 573 /* 574 * Set default limits for VM system. 575 * Called for proc 0, and then inherited by all others. 576 * 577 * XXX should probably act directly on proc0. 578 */ 579 static void 580 vm_init_limits(udata) 581 void *udata; 582 { 583 struct proc *p = udata; 584 struct plimit *limp; 585 int rss_limit; 586 587 /* 588 * Set up the initial limits on process VM. Set the maximum resident 589 * set size to be half of (reasonably) available memory. Since this 590 * is a soft limit, it comes into effect only when the system is out 591 * of memory - half of main memory helps to favor smaller processes, 592 * and reduces thrashing of the object cache. 593 */ 594 limp = p->p_limit; 595 limp->pl_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 596 limp->pl_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 597 limp->pl_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 598 limp->pl_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 599 /* limit the limit to no less than 2MB */ 600 rss_limit = max(cnt.v_free_count, 512); 601 limp->pl_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 602 limp->pl_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 603 } 604 605 void 606 faultin(p) 607 struct proc *p; 608 { 609 #ifdef NO_SWAPPING 610 611 PROC_LOCK_ASSERT(p, MA_OWNED); 612 if ((p->p_flag & P_INMEM) == 0) 613 panic("faultin: proc swapped out with NO_SWAPPING!"); 614 #else /* !NO_SWAPPING */ 615 struct thread *td; 616 617 PROC_LOCK_ASSERT(p, MA_OWNED); 618 /* 619 * If another process is swapping in this process, 620 * just wait until it finishes. 621 */ 622 if (p->p_flag & P_SWAPPINGIN) { 623 while (p->p_flag & P_SWAPPINGIN) 624 msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0); 625 return; 626 } 627 if ((p->p_flag & P_INMEM) == 0) { 628 /* 629 * Don't let another thread swap process p out while we are 630 * busy swapping it in. 631 */ 632 ++p->p_lock; 633 p->p_flag |= P_SWAPPINGIN; 634 PROC_UNLOCK(p); 635 636 /* 637 * We hold no lock here because the list of threads 638 * can not change while all threads in the process are 639 * swapped out. 640 */ 641 FOREACH_THREAD_IN_PROC(p, td) 642 vm_thread_swapin(td); 643 PROC_LOCK(p); 644 swapclear(p); 645 p->p_swtick = ticks; 646 647 wakeup(&p->p_flag); 648 649 /* Allow other threads to swap p out now. */ 650 --p->p_lock; 651 } 652 #endif /* NO_SWAPPING */ 653 } 654 655 /* 656 * This swapin algorithm attempts to swap-in processes only if there 657 * is enough space for them. Of course, if a process waits for a long 658 * time, it will be swapped in anyway. 659 * 660 * Giant is held on entry. 661 */ 662 /* ARGSUSED*/ 663 static void 664 scheduler(dummy) 665 void *dummy; 666 { 667 struct proc *p; 668 struct thread *td; 669 struct proc *pp; 670 int slptime; 671 int swtime; 672 int ppri; 673 int pri; 674 675 mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED); 676 mtx_unlock(&Giant); 677 678 loop: 679 if (vm_page_count_min()) { 680 VM_WAIT; 681 goto loop; 682 } 683 684 pp = NULL; 685 ppri = INT_MIN; 686 sx_slock(&allproc_lock); 687 FOREACH_PROC_IN_SYSTEM(p) { 688 PROC_LOCK(p); 689 if (p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) { 690 PROC_UNLOCK(p); 691 continue; 692 } 693 swtime = (ticks - p->p_swtick) / hz; 694 FOREACH_THREAD_IN_PROC(p, td) { 695 /* 696 * An otherwise runnable thread of a process 697 * swapped out has only the TDI_SWAPPED bit set. 698 * 699 */ 700 thread_lock(td); 701 if (td->td_inhibitors == TDI_SWAPPED) { 702 slptime = (ticks - td->td_slptick) / hz; 703 pri = swtime + slptime; 704 if ((td->td_flags & TDF_SWAPINREQ) == 0) 705 pri -= p->p_nice * 8; 706 /* 707 * if this thread is higher priority 708 * and there is enough space, then select 709 * this process instead of the previous 710 * selection. 711 */ 712 if (pri > ppri) { 713 pp = p; 714 ppri = pri; 715 } 716 } 717 thread_unlock(td); 718 } 719 PROC_UNLOCK(p); 720 } 721 sx_sunlock(&allproc_lock); 722 723 /* 724 * Nothing to do, back to sleep. 725 */ 726 if ((p = pp) == NULL) { 727 tsleep(&proc0, PVM, "sched", maxslp * hz / 2); 728 goto loop; 729 } 730 PROC_LOCK(p); 731 732 /* 733 * Another process may be bringing or may have already 734 * brought this process in while we traverse all threads. 735 * Or, this process may even be being swapped out again. 736 */ 737 if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) { 738 PROC_UNLOCK(p); 739 goto loop; 740 } 741 742 /* 743 * We would like to bring someone in. (only if there is space). 744 * [What checks the space? ] 745 */ 746 faultin(p); 747 PROC_UNLOCK(p); 748 goto loop; 749 } 750 751 void 752 kick_proc0(void) 753 { 754 755 wakeup(&proc0); 756 } 757 758 #ifndef NO_SWAPPING 759 760 /* 761 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 762 */ 763 static int swap_idle_threshold1 = 2; 764 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW, 765 &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process"); 766 767 /* 768 * Swap_idle_threshold2 is the time that a process can be idle before 769 * it will be swapped out, if idle swapping is enabled. 770 */ 771 static int swap_idle_threshold2 = 10; 772 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW, 773 &swap_idle_threshold2, 0, "Time before a process will be swapped out"); 774 775 /* 776 * Swapout is driven by the pageout daemon. Very simple, we find eligible 777 * procs and swap out their stacks. We try to always "swap" at least one 778 * process in case we need the room for a swapin. 779 * If any procs have been sleeping/stopped for at least maxslp seconds, 780 * they are swapped. Else, we swap the longest-sleeping or stopped process, 781 * if any, otherwise the longest-resident process. 782 */ 783 void 784 swapout_procs(action) 785 int action; 786 { 787 struct proc *p; 788 struct thread *td; 789 int didswap = 0; 790 791 retry: 792 sx_slock(&allproc_lock); 793 FOREACH_PROC_IN_SYSTEM(p) { 794 struct vmspace *vm; 795 int minslptime = 100000; 796 int slptime; 797 798 /* 799 * Watch out for a process in 800 * creation. It may have no 801 * address space or lock yet. 802 */ 803 if (p->p_state == PRS_NEW) 804 continue; 805 /* 806 * An aio daemon switches its 807 * address space while running. 808 * Perform a quick check whether 809 * a process has P_SYSTEM. 810 */ 811 if ((p->p_flag & P_SYSTEM) != 0) 812 continue; 813 /* 814 * Do not swapout a process that 815 * is waiting for VM data 816 * structures as there is a possible 817 * deadlock. Test this first as 818 * this may block. 819 * 820 * Lock the map until swapout 821 * finishes, or a thread of this 822 * process may attempt to alter 823 * the map. 824 */ 825 vm = vmspace_acquire_ref(p); 826 if (vm == NULL) 827 continue; 828 if (!vm_map_trylock(&vm->vm_map)) 829 goto nextproc1; 830 831 PROC_LOCK(p); 832 if (p->p_lock != 0 || 833 (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT) 834 ) != 0) { 835 goto nextproc; 836 } 837 /* 838 * only aiod changes vmspace, however it will be 839 * skipped because of the if statement above checking 840 * for P_SYSTEM 841 */ 842 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM) 843 goto nextproc; 844 845 switch (p->p_state) { 846 default: 847 /* Don't swap out processes in any sort 848 * of 'special' state. */ 849 break; 850 851 case PRS_NORMAL: 852 /* 853 * do not swapout a realtime process 854 * Check all the thread groups.. 855 */ 856 FOREACH_THREAD_IN_PROC(p, td) { 857 thread_lock(td); 858 if (PRI_IS_REALTIME(td->td_pri_class)) { 859 thread_unlock(td); 860 goto nextproc; 861 } 862 slptime = (ticks - td->td_slptick) / hz; 863 /* 864 * Guarantee swap_idle_threshold1 865 * time in memory. 866 */ 867 if (slptime < swap_idle_threshold1) { 868 thread_unlock(td); 869 goto nextproc; 870 } 871 872 /* 873 * Do not swapout a process if it is 874 * waiting on a critical event of some 875 * kind or there is a thread whose 876 * pageable memory may be accessed. 877 * 878 * This could be refined to support 879 * swapping out a thread. 880 */ 881 if (!thread_safetoswapout(td)) { 882 thread_unlock(td); 883 goto nextproc; 884 } 885 /* 886 * If the system is under memory stress, 887 * or if we are swapping 888 * idle processes >= swap_idle_threshold2, 889 * then swap the process out. 890 */ 891 if (((action & VM_SWAP_NORMAL) == 0) && 892 (((action & VM_SWAP_IDLE) == 0) || 893 (slptime < swap_idle_threshold2))) { 894 thread_unlock(td); 895 goto nextproc; 896 } 897 898 if (minslptime > slptime) 899 minslptime = slptime; 900 thread_unlock(td); 901 } 902 903 /* 904 * If the pageout daemon didn't free enough pages, 905 * or if this process is idle and the system is 906 * configured to swap proactively, swap it out. 907 */ 908 if ((action & VM_SWAP_NORMAL) || 909 ((action & VM_SWAP_IDLE) && 910 (minslptime > swap_idle_threshold2))) { 911 if (swapout(p) == 0) 912 didswap++; 913 PROC_UNLOCK(p); 914 vm_map_unlock(&vm->vm_map); 915 vmspace_free(vm); 916 sx_sunlock(&allproc_lock); 917 goto retry; 918 } 919 } 920 nextproc: 921 PROC_UNLOCK(p); 922 vm_map_unlock(&vm->vm_map); 923 nextproc1: 924 vmspace_free(vm); 925 continue; 926 } 927 sx_sunlock(&allproc_lock); 928 /* 929 * If we swapped something out, and another process needed memory, 930 * then wakeup the sched process. 931 */ 932 if (didswap) 933 wakeup(&proc0); 934 } 935 936 static void 937 swapclear(p) 938 struct proc *p; 939 { 940 struct thread *td; 941 942 PROC_LOCK_ASSERT(p, MA_OWNED); 943 944 FOREACH_THREAD_IN_PROC(p, td) { 945 thread_lock(td); 946 td->td_flags |= TDF_INMEM; 947 td->td_flags &= ~TDF_SWAPINREQ; 948 TD_CLR_SWAPPED(td); 949 if (TD_CAN_RUN(td)) 950 if (setrunnable(td)) { 951 #ifdef INVARIANTS 952 /* 953 * XXX: We just cleared TDI_SWAPPED 954 * above and set TDF_INMEM, so this 955 * should never happen. 956 */ 957 panic("not waking up swapper"); 958 #endif 959 } 960 thread_unlock(td); 961 } 962 p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT); 963 p->p_flag |= P_INMEM; 964 } 965 966 static int 967 swapout(p) 968 struct proc *p; 969 { 970 struct thread *td; 971 972 PROC_LOCK_ASSERT(p, MA_OWNED); 973 #if defined(SWAP_DEBUG) 974 printf("swapping out %d\n", p->p_pid); 975 #endif 976 977 /* 978 * The states of this process and its threads may have changed 979 * by now. Assuming that there is only one pageout daemon thread, 980 * this process should still be in memory. 981 */ 982 KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM, 983 ("swapout: lost a swapout race?")); 984 985 /* 986 * remember the process resident count 987 */ 988 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 989 /* 990 * Check and mark all threads before we proceed. 991 */ 992 p->p_flag &= ~P_INMEM; 993 p->p_flag |= P_SWAPPINGOUT; 994 FOREACH_THREAD_IN_PROC(p, td) { 995 thread_lock(td); 996 if (!thread_safetoswapout(td)) { 997 thread_unlock(td); 998 swapclear(p); 999 return (EBUSY); 1000 } 1001 td->td_flags &= ~TDF_INMEM; 1002 TD_SET_SWAPPED(td); 1003 thread_unlock(td); 1004 } 1005 td = FIRST_THREAD_IN_PROC(p); 1006 ++td->td_ru.ru_nswap; 1007 PROC_UNLOCK(p); 1008 1009 /* 1010 * This list is stable because all threads are now prevented from 1011 * running. The list is only modified in the context of a running 1012 * thread in this process. 1013 */ 1014 FOREACH_THREAD_IN_PROC(p, td) 1015 vm_thread_swapout(td); 1016 1017 PROC_LOCK(p); 1018 p->p_flag &= ~P_SWAPPINGOUT; 1019 p->p_swtick = ticks; 1020 return (0); 1021 } 1022 #endif /* !NO_SWAPPING */ 1023