1 /* $NetBSD: uvm_pdaemon.c,v 1.77 2006/09/15 15:51:13 yamt Exp $ */ 2 3 /* 4 * Copyright (c) 1997 Charles D. Cranor and Washington University. 5 * Copyright (c) 1991, 1993, The Regents of the University of California. 6 * 7 * All rights reserved. 8 * 9 * This code is derived from software contributed to Berkeley by 10 * The Mach Operating System project at Carnegie-Mellon University. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by Charles D. Cranor, 23 * Washington University, the University of California, Berkeley and 24 * its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * @(#)vm_pageout.c 8.5 (Berkeley) 2/14/94 42 * from: Id: uvm_pdaemon.c,v 1.1.2.32 1998/02/06 05:26:30 chs Exp 43 * 44 * 45 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 46 * All rights reserved. 47 * 48 * Permission to use, copy, modify and distribute this software and 49 * its documentation is hereby granted, provided that both the copyright 50 * notice and this permission notice appear in all copies of the 51 * software, derivative works or modified versions, and any portions 52 * thereof, and that both notices appear in supporting documentation. 53 * 54 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 55 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 56 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 57 * 58 * Carnegie Mellon requests users of this software to return to 59 * 60 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 61 * School of Computer Science 62 * Carnegie Mellon University 63 * Pittsburgh PA 15213-3890 64 * 65 * any improvements or extensions that they make and grant Carnegie the 66 * rights to redistribute these changes. 67 */ 68 69 /* 70 * uvm_pdaemon.c: the page daemon 71 */ 72 73 #include <sys/cdefs.h> 74 __KERNEL_RCSID(0, "$NetBSD: uvm_pdaemon.c,v 1.77 2006/09/15 15:51:13 yamt Exp $"); 75 76 #include "opt_uvmhist.h" 77 #include "opt_readahead.h" 78 79 #include <sys/param.h> 80 #include <sys/proc.h> 81 #include <sys/systm.h> 82 #include <sys/kernel.h> 83 #include <sys/pool.h> 84 #include <sys/buf.h> 85 #include <sys/vnode.h> 86 87 #include <uvm/uvm.h> 88 #include <uvm/uvm_pdpolicy.h> 89 90 /* 91 * UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedaemon will reactivate 92 * in a pass thru the inactive list when swap is full. the value should be 93 * "small"... if it's too large we'll cycle the active pages thru the inactive 94 * queue too quickly to for them to be referenced and avoid being freed. 95 */ 96 97 #define UVMPD_NUMDIRTYREACTS 16 98 99 100 /* 101 * local prototypes 102 */ 103 104 static void uvmpd_scan(void); 105 static void uvmpd_scan_queue(void); 106 static void uvmpd_tune(void); 107 108 /* 109 * XXX hack to avoid hangs when large processes fork. 110 */ 111 int uvm_extrapages; 112 113 /* 114 * uvm_wait: wait (sleep) for the page daemon to free some pages 115 * 116 * => should be called with all locks released 117 * => should _not_ be called by the page daemon (to avoid deadlock) 118 */ 119 120 void 121 uvm_wait(const char *wmsg) 122 { 123 int timo = 0; 124 int s = splbio(); 125 126 /* 127 * check for page daemon going to sleep (waiting for itself) 128 */ 129 130 if (curproc == uvm.pagedaemon_proc && uvmexp.paging == 0) { 131 /* 132 * now we have a problem: the pagedaemon wants to go to 133 * sleep until it frees more memory. but how can it 134 * free more memory if it is asleep? that is a deadlock. 135 * we have two options: 136 * [1] panic now 137 * [2] put a timeout on the sleep, thus causing the 138 * pagedaemon to only pause (rather than sleep forever) 139 * 140 * note that option [2] will only help us if we get lucky 141 * and some other process on the system breaks the deadlock 142 * by exiting or freeing memory (thus allowing the pagedaemon 143 * to continue). for now we panic if DEBUG is defined, 144 * otherwise we hope for the best with option [2] (better 145 * yet, this should never happen in the first place!). 146 */ 147 148 printf("pagedaemon: deadlock detected!\n"); 149 timo = hz >> 3; /* set timeout */ 150 #if defined(DEBUG) 151 /* DEBUG: panic so we can debug it */ 152 panic("pagedaemon deadlock"); 153 #endif 154 } 155 156 simple_lock(&uvm.pagedaemon_lock); 157 wakeup(&uvm.pagedaemon); /* wake the daemon! */ 158 UVM_UNLOCK_AND_WAIT(&uvmexp.free, &uvm.pagedaemon_lock, FALSE, wmsg, 159 timo); 160 161 splx(s); 162 } 163 164 /* 165 * uvm_kick_pdaemon: perform checks to determine if we need to 166 * give the pagedaemon a nudge, and do so if necessary. 167 */ 168 169 void 170 uvm_kick_pdaemon(void) 171 { 172 173 if (uvmexp.free + uvmexp.paging < uvmexp.freemin || 174 (uvmexp.free + uvmexp.paging < uvmexp.freetarg && 175 uvmpdpol_needsscan_p())) { 176 wakeup(&uvm.pagedaemon); 177 } 178 } 179 180 /* 181 * uvmpd_tune: tune paging parameters 182 * 183 * => called when ever memory is added (or removed?) to the system 184 * => caller must call with page queues locked 185 */ 186 187 static void 188 uvmpd_tune(void) 189 { 190 UVMHIST_FUNC("uvmpd_tune"); UVMHIST_CALLED(pdhist); 191 192 uvmexp.freemin = uvmexp.npages / 20; 193 194 /* between 16k and 256k */ 195 /* XXX: what are these values good for? */ 196 uvmexp.freemin = MAX(uvmexp.freemin, (16*1024) >> PAGE_SHIFT); 197 uvmexp.freemin = MIN(uvmexp.freemin, (256*1024) >> PAGE_SHIFT); 198 199 /* Make sure there's always a user page free. */ 200 if (uvmexp.freemin < uvmexp.reserve_kernel + 1) 201 uvmexp.freemin = uvmexp.reserve_kernel + 1; 202 203 uvmexp.freetarg = (uvmexp.freemin * 4) / 3; 204 if (uvmexp.freetarg <= uvmexp.freemin) 205 uvmexp.freetarg = uvmexp.freemin + 1; 206 207 uvmexp.freetarg += uvm_extrapages; 208 uvm_extrapages = 0; 209 210 uvmexp.wiredmax = uvmexp.npages / 3; 211 UVMHIST_LOG(pdhist, "<- done, freemin=%d, freetarg=%d, wiredmax=%d", 212 uvmexp.freemin, uvmexp.freetarg, uvmexp.wiredmax, 0); 213 } 214 215 /* 216 * uvm_pageout: the main loop for the pagedaemon 217 */ 218 219 void 220 uvm_pageout(void *arg) 221 { 222 int bufcnt, npages = 0; 223 int extrapages = 0; 224 UVMHIST_FUNC("uvm_pageout"); UVMHIST_CALLED(pdhist); 225 226 UVMHIST_LOG(pdhist,"<starting uvm pagedaemon>", 0, 0, 0, 0); 227 228 /* 229 * ensure correct priority and set paging parameters... 230 */ 231 232 uvm.pagedaemon_proc = curproc; 233 uvm_lock_pageq(); 234 npages = uvmexp.npages; 235 uvmpd_tune(); 236 uvm_unlock_pageq(); 237 238 /* 239 * main loop 240 */ 241 242 for (;;) { 243 simple_lock(&uvm.pagedaemon_lock); 244 245 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 246 UVM_UNLOCK_AND_WAIT(&uvm.pagedaemon, 247 &uvm.pagedaemon_lock, FALSE, "pgdaemon", 0); 248 uvmexp.pdwoke++; 249 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 250 251 /* 252 * now lock page queues and recompute inactive count 253 */ 254 255 uvm_lock_pageq(); 256 if (npages != uvmexp.npages || extrapages != uvm_extrapages) { 257 npages = uvmexp.npages; 258 extrapages = uvm_extrapages; 259 uvmpd_tune(); 260 } 261 262 uvmpdpol_tune(); 263 264 /* 265 * Estimate a hint. Note that bufmem are returned to 266 * system only when entire pool page is empty. 267 */ 268 bufcnt = uvmexp.freetarg - uvmexp.free; 269 if (bufcnt < 0) 270 bufcnt = 0; 271 272 UVMHIST_LOG(pdhist," free/ftarg=%d/%d", 273 uvmexp.free, uvmexp.freetarg, 0,0); 274 275 /* 276 * scan if needed 277 */ 278 279 if (uvmexp.free + uvmexp.paging < uvmexp.freetarg || 280 uvmpdpol_needsscan_p()) { 281 uvmpd_scan(); 282 } 283 284 /* 285 * if there's any free memory to be had, 286 * wake up any waiters. 287 */ 288 289 if (uvmexp.free > uvmexp.reserve_kernel || 290 uvmexp.paging == 0) { 291 wakeup(&uvmexp.free); 292 } 293 294 /* 295 * scan done. unlock page queues (the only lock we are holding) 296 */ 297 298 uvm_unlock_pageq(); 299 300 buf_drain(bufcnt << PAGE_SHIFT); 301 302 /* 303 * drain pool resources now that we're not holding any locks 304 */ 305 306 pool_drain(0); 307 308 /* 309 * free any cached u-areas we don't need 310 */ 311 uvm_uarea_drain(TRUE); 312 313 } 314 /*NOTREACHED*/ 315 } 316 317 318 /* 319 * uvm_aiodone_daemon: main loop for the aiodone daemon. 320 */ 321 322 void 323 uvm_aiodone_daemon(void *arg) 324 { 325 int s, free; 326 struct buf *bp, *nbp; 327 UVMHIST_FUNC("uvm_aiodoned"); UVMHIST_CALLED(pdhist); 328 329 for (;;) { 330 331 /* 332 * carefully attempt to go to sleep (without losing "wakeups"!). 333 * we need splbio because we want to make sure the aio_done list 334 * is totally empty before we go to sleep. 335 */ 336 337 s = splbio(); 338 simple_lock(&uvm.aiodoned_lock); 339 if (TAILQ_FIRST(&uvm.aio_done) == NULL) { 340 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 341 UVM_UNLOCK_AND_WAIT(&uvm.aiodoned, 342 &uvm.aiodoned_lock, FALSE, "aiodoned", 0); 343 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 344 345 /* relock aiodoned_lock, still at splbio */ 346 simple_lock(&uvm.aiodoned_lock); 347 } 348 349 /* 350 * check for done aio structures 351 */ 352 353 bp = TAILQ_FIRST(&uvm.aio_done); 354 if (bp) { 355 TAILQ_INIT(&uvm.aio_done); 356 } 357 358 simple_unlock(&uvm.aiodoned_lock); 359 splx(s); 360 361 /* 362 * process each i/o that's done. 363 */ 364 365 free = uvmexp.free; 366 while (bp != NULL) { 367 nbp = TAILQ_NEXT(bp, b_freelist); 368 (*bp->b_iodone)(bp); 369 bp = nbp; 370 } 371 if (free <= uvmexp.reserve_kernel) { 372 s = uvm_lock_fpageq(); 373 wakeup(&uvm.pagedaemon); 374 uvm_unlock_fpageq(s); 375 } else { 376 simple_lock(&uvm.pagedaemon_lock); 377 wakeup(&uvmexp.free); 378 simple_unlock(&uvm.pagedaemon_lock); 379 } 380 } 381 } 382 383 /* 384 * uvmpd_trylockowner: trylock the page's owner. 385 * 386 * => called with pageq locked. 387 * => resolve orphaned O->A loaned page. 388 * => return the locked simplelock on success. otherwise, return NULL. 389 */ 390 391 struct simplelock * 392 uvmpd_trylockowner(struct vm_page *pg) 393 { 394 struct uvm_object *uobj = pg->uobject; 395 struct simplelock *slock; 396 397 UVM_LOCK_ASSERT_PAGEQ(); 398 if (uobj != NULL) { 399 slock = &uobj->vmobjlock; 400 } else { 401 struct vm_anon *anon = pg->uanon; 402 403 KASSERT(anon != NULL); 404 slock = &anon->an_lock; 405 } 406 407 if (!simple_lock_try(slock)) { 408 return NULL; 409 } 410 411 if (uobj == NULL) { 412 413 /* 414 * set PQ_ANON if it isn't set already. 415 */ 416 417 if ((pg->pqflags & PQ_ANON) == 0) { 418 KASSERT(pg->loan_count > 0); 419 pg->loan_count--; 420 pg->pqflags |= PQ_ANON; 421 /* anon now owns it */ 422 } 423 } 424 425 return slock; 426 } 427 428 #if defined(VMSWAP) 429 struct swapcluster { 430 int swc_slot; 431 int swc_nallocated; 432 int swc_nused; 433 struct vm_page *swc_pages[howmany(MAXPHYS, MIN_PAGE_SIZE)]; 434 }; 435 436 static void 437 swapcluster_init(struct swapcluster *swc) 438 { 439 440 swc->swc_slot = 0; 441 } 442 443 static int 444 swapcluster_allocslots(struct swapcluster *swc) 445 { 446 int slot; 447 int npages; 448 449 if (swc->swc_slot != 0) { 450 return 0; 451 } 452 453 /* Even with strange MAXPHYS, the shift 454 implicitly rounds down to a page. */ 455 npages = MAXPHYS >> PAGE_SHIFT; 456 slot = uvm_swap_alloc(&npages, TRUE); 457 if (slot == 0) { 458 return ENOMEM; 459 } 460 swc->swc_slot = slot; 461 swc->swc_nallocated = npages; 462 swc->swc_nused = 0; 463 464 return 0; 465 } 466 467 static int 468 swapcluster_add(struct swapcluster *swc, struct vm_page *pg) 469 { 470 int slot; 471 struct uvm_object *uobj; 472 473 KASSERT(swc->swc_slot != 0); 474 KASSERT(swc->swc_nused < swc->swc_nallocated); 475 KASSERT((pg->pqflags & PQ_SWAPBACKED) != 0); 476 477 slot = swc->swc_slot + swc->swc_nused; 478 uobj = pg->uobject; 479 if (uobj == NULL) { 480 LOCK_ASSERT(simple_lock_held(&pg->uanon->an_lock)); 481 pg->uanon->an_swslot = slot; 482 } else { 483 int result; 484 485 LOCK_ASSERT(simple_lock_held(&uobj->vmobjlock)); 486 result = uao_set_swslot(uobj, pg->offset >> PAGE_SHIFT, slot); 487 if (result == -1) { 488 return ENOMEM; 489 } 490 } 491 swc->swc_pages[swc->swc_nused] = pg; 492 swc->swc_nused++; 493 494 return 0; 495 } 496 497 static void 498 swapcluster_flush(struct swapcluster *swc, boolean_t now) 499 { 500 int slot; 501 int nused; 502 int nallocated; 503 int error; 504 505 if (swc->swc_slot == 0) { 506 return; 507 } 508 KASSERT(swc->swc_nused <= swc->swc_nallocated); 509 510 slot = swc->swc_slot; 511 nused = swc->swc_nused; 512 nallocated = swc->swc_nallocated; 513 514 /* 515 * if this is the final pageout we could have a few 516 * unused swap blocks. if so, free them now. 517 */ 518 519 if (nused < nallocated) { 520 if (!now) { 521 return; 522 } 523 uvm_swap_free(slot + nused, nallocated - nused); 524 } 525 526 /* 527 * now start the pageout. 528 */ 529 530 uvmexp.pdpageouts++; 531 error = uvm_swap_put(slot, swc->swc_pages, nused, 0); 532 KASSERT(error == 0); 533 534 /* 535 * zero swslot to indicate that we are 536 * no longer building a swap-backed cluster. 537 */ 538 539 swc->swc_slot = 0; 540 } 541 542 /* 543 * uvmpd_dropswap: free any swap allocated to this page. 544 * 545 * => called with owner locked. 546 * => return TRUE if a page had an associated slot. 547 */ 548 549 static boolean_t 550 uvmpd_dropswap(struct vm_page *pg) 551 { 552 boolean_t result = FALSE; 553 struct vm_anon *anon = pg->uanon; 554 555 if ((pg->pqflags & PQ_ANON) && anon->an_swslot) { 556 uvm_swap_free(anon->an_swslot, 1); 557 anon->an_swslot = 0; 558 pg->flags &= ~PG_CLEAN; 559 result = TRUE; 560 } else if (pg->pqflags & PQ_AOBJ) { 561 int slot = uao_set_swslot(pg->uobject, 562 pg->offset >> PAGE_SHIFT, 0); 563 if (slot) { 564 uvm_swap_free(slot, 1); 565 pg->flags &= ~PG_CLEAN; 566 result = TRUE; 567 } 568 } 569 570 return result; 571 } 572 573 /* 574 * uvmpd_trydropswap: try to free any swap allocated to this page. 575 * 576 * => return TRUE if a slot is successfully freed. 577 */ 578 579 boolean_t 580 uvmpd_trydropswap(struct vm_page *pg) 581 { 582 struct simplelock *slock; 583 boolean_t result; 584 585 if ((pg->flags & PG_BUSY) != 0) { 586 return FALSE; 587 } 588 589 /* 590 * lock the page's owner. 591 */ 592 593 slock = uvmpd_trylockowner(pg); 594 if (slock == NULL) { 595 return FALSE; 596 } 597 598 /* 599 * skip this page if it's busy. 600 */ 601 602 if ((pg->flags & PG_BUSY) != 0) { 603 simple_unlock(slock); 604 return FALSE; 605 } 606 607 result = uvmpd_dropswap(pg); 608 609 simple_unlock(slock); 610 611 return result; 612 } 613 614 #endif /* defined(VMSWAP) */ 615 616 /* 617 * uvmpd_scan_queue: scan an replace candidate list for pages 618 * to clean or free. 619 * 620 * => called with page queues locked 621 * => we work on meeting our free target by converting inactive pages 622 * into free pages. 623 * => we handle the building of swap-backed clusters 624 */ 625 626 static void 627 uvmpd_scan_queue(void) 628 { 629 struct vm_page *p; 630 struct uvm_object *uobj; 631 struct vm_anon *anon; 632 #if defined(VMSWAP) 633 struct swapcluster swc; 634 #endif /* defined(VMSWAP) */ 635 int dirtyreacts; 636 struct simplelock *slock; 637 UVMHIST_FUNC("uvmpd_scan_queue"); UVMHIST_CALLED(pdhist); 638 639 /* 640 * swslot is non-zero if we are building a swap cluster. we want 641 * to stay in the loop while we have a page to scan or we have 642 * a swap-cluster to build. 643 */ 644 645 #if defined(VMSWAP) 646 swapcluster_init(&swc); 647 #endif /* defined(VMSWAP) */ 648 649 dirtyreacts = 0; 650 uvmpdpol_scaninit(); 651 652 while (/* CONSTCOND */ 1) { 653 654 /* 655 * see if we've met the free target. 656 */ 657 658 if (uvmexp.free + uvmexp.paging >= uvmexp.freetarg << 2 || 659 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 660 UVMHIST_LOG(pdhist," met free target: " 661 "exit loop", 0, 0, 0, 0); 662 break; 663 } 664 665 p = uvmpdpol_selectvictim(); 666 if (p == NULL) { 667 break; 668 } 669 KASSERT(uvmpdpol_pageisqueued_p(p)); 670 KASSERT(p->wire_count == 0); 671 672 /* 673 * we are below target and have a new page to consider. 674 */ 675 676 anon = p->uanon; 677 uobj = p->uobject; 678 679 /* 680 * first we attempt to lock the object that this page 681 * belongs to. if our attempt fails we skip on to 682 * the next page (no harm done). it is important to 683 * "try" locking the object as we are locking in the 684 * wrong order (pageq -> object) and we don't want to 685 * deadlock. 686 * 687 * the only time we expect to see an ownerless page 688 * (i.e. a page with no uobject and !PQ_ANON) is if an 689 * anon has loaned a page from a uvm_object and the 690 * uvm_object has dropped the ownership. in that 691 * case, the anon can "take over" the loaned page 692 * and make it its own. 693 */ 694 695 slock = uvmpd_trylockowner(p); 696 if (slock == NULL) { 697 continue; 698 } 699 if (p->flags & PG_BUSY) { 700 simple_unlock(slock); 701 uvmexp.pdbusy++; 702 continue; 703 } 704 705 /* does the page belong to an object? */ 706 if (uobj != NULL) { 707 uvmexp.pdobscan++; 708 } else { 709 #if defined(VMSWAP) 710 KASSERT(anon != NULL); 711 uvmexp.pdanscan++; 712 #else /* defined(VMSWAP) */ 713 panic("%s: anon", __func__); 714 #endif /* defined(VMSWAP) */ 715 } 716 717 718 /* 719 * we now have the object and the page queues locked. 720 * if the page is not swap-backed, call the object's 721 * pager to flush and free the page. 722 */ 723 724 #if defined(READAHEAD_STATS) 725 if ((p->pqflags & PQ_READAHEAD) != 0) { 726 p->pqflags &= ~PQ_READAHEAD; 727 uvm_ra_miss.ev_count++; 728 } 729 #endif /* defined(READAHEAD_STATS) */ 730 731 if ((p->pqflags & PQ_SWAPBACKED) == 0) { 732 uvm_unlock_pageq(); 733 (void) (uobj->pgops->pgo_put)(uobj, p->offset, 734 p->offset + PAGE_SIZE, PGO_CLEANIT|PGO_FREE); 735 uvm_lock_pageq(); 736 continue; 737 } 738 739 /* 740 * the page is swap-backed. remove all the permissions 741 * from the page so we can sync the modified info 742 * without any race conditions. if the page is clean 743 * we can free it now and continue. 744 */ 745 746 pmap_page_protect(p, VM_PROT_NONE); 747 if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) { 748 p->flags &= ~(PG_CLEAN); 749 } 750 if (p->flags & PG_CLEAN) { 751 int slot; 752 int pageidx; 753 754 pageidx = p->offset >> PAGE_SHIFT; 755 uvm_pagefree(p); 756 uvmexp.pdfreed++; 757 758 /* 759 * for anons, we need to remove the page 760 * from the anon ourselves. for aobjs, 761 * pagefree did that for us. 762 */ 763 764 if (anon) { 765 KASSERT(anon->an_swslot != 0); 766 anon->an_page = NULL; 767 slot = anon->an_swslot; 768 } else { 769 slot = uao_find_swslot(uobj, pageidx); 770 } 771 simple_unlock(slock); 772 773 if (slot > 0) { 774 /* this page is now only in swap. */ 775 simple_lock(&uvm.swap_data_lock); 776 KASSERT(uvmexp.swpgonly < uvmexp.swpginuse); 777 uvmexp.swpgonly++; 778 simple_unlock(&uvm.swap_data_lock); 779 } 780 continue; 781 } 782 783 #if defined(VMSWAP) 784 /* 785 * this page is dirty, skip it if we'll have met our 786 * free target when all the current pageouts complete. 787 */ 788 789 if (uvmexp.free + uvmexp.paging > uvmexp.freetarg << 2) { 790 simple_unlock(slock); 791 continue; 792 } 793 794 /* 795 * free any swap space allocated to the page since 796 * we'll have to write it again with its new data. 797 */ 798 799 uvmpd_dropswap(p); 800 801 /* 802 * if all pages in swap are only in swap, 803 * the swap space is full and we can't page out 804 * any more swap-backed pages. reactivate this page 805 * so that we eventually cycle all pages through 806 * the inactive queue. 807 */ 808 809 if (uvm_swapisfull()) { 810 dirtyreacts++; 811 uvm_pageactivate(p); 812 simple_unlock(slock); 813 continue; 814 } 815 816 /* 817 * start new swap pageout cluster (if necessary). 818 */ 819 820 if (swapcluster_allocslots(&swc)) { 821 simple_unlock(slock); 822 dirtyreacts++; /* XXX */ 823 continue; 824 } 825 826 /* 827 * at this point, we're definitely going reuse this 828 * page. mark the page busy and delayed-free. 829 * we should remove the page from the page queues 830 * so we don't ever look at it again. 831 * adjust counters and such. 832 */ 833 834 p->flags |= PG_BUSY; 835 UVM_PAGE_OWN(p, "scan_queue"); 836 837 p->flags |= PG_PAGEOUT; 838 uvmexp.paging++; 839 uvm_pagedequeue(p); 840 841 uvmexp.pgswapout++; 842 uvm_unlock_pageq(); 843 844 /* 845 * add the new page to the cluster. 846 */ 847 848 if (swapcluster_add(&swc, p)) { 849 p->flags &= ~(PG_BUSY|PG_PAGEOUT); 850 UVM_PAGE_OWN(p, NULL); 851 uvm_lock_pageq(); 852 uvmexp.paging--; 853 dirtyreacts++; 854 uvm_pageactivate(p); 855 simple_unlock(slock); 856 continue; 857 } 858 simple_unlock(slock); 859 860 swapcluster_flush(&swc, FALSE); 861 uvm_lock_pageq(); 862 863 /* 864 * the pageout is in progress. bump counters and set up 865 * for the next loop. 866 */ 867 868 uvmexp.pdpending++; 869 870 #else /* defined(VMSWAP) */ 871 uvm_pageactivate(p); 872 simple_unlock(slock); 873 #endif /* defined(VMSWAP) */ 874 } 875 876 #if defined(VMSWAP) 877 uvm_unlock_pageq(); 878 swapcluster_flush(&swc, TRUE); 879 uvm_lock_pageq(); 880 #endif /* defined(VMSWAP) */ 881 } 882 883 /* 884 * uvmpd_scan: scan the page queues and attempt to meet our targets. 885 * 886 * => called with pageq's locked 887 */ 888 889 static void 890 uvmpd_scan(void) 891 { 892 int swap_shortage, pages_freed; 893 UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist); 894 895 uvmexp.pdrevs++; 896 897 #ifndef __SWAP_BROKEN 898 899 /* 900 * swap out some processes if we are below our free target. 901 * we need to unlock the page queues for this. 902 */ 903 904 if (uvmexp.free < uvmexp.freetarg && uvmexp.nswapdev != 0) { 905 uvmexp.pdswout++; 906 UVMHIST_LOG(pdhist," free %d < target %d: swapout", 907 uvmexp.free, uvmexp.freetarg, 0, 0); 908 uvm_unlock_pageq(); 909 uvm_swapout_threads(); 910 uvm_lock_pageq(); 911 912 } 913 #endif 914 915 /* 916 * now we want to work on meeting our targets. first we work on our 917 * free target by converting inactive pages into free pages. then 918 * we work on meeting our inactive target by converting active pages 919 * to inactive ones. 920 */ 921 922 UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0); 923 924 pages_freed = uvmexp.pdfreed; 925 uvmpd_scan_queue(); 926 pages_freed = uvmexp.pdfreed - pages_freed; 927 928 /* 929 * detect if we're not going to be able to page anything out 930 * until we free some swap resources from active pages. 931 */ 932 933 swap_shortage = 0; 934 if (uvmexp.free < uvmexp.freetarg && 935 uvmexp.swpginuse >= uvmexp.swpgavail && 936 !uvm_swapisfull() && 937 pages_freed == 0) { 938 swap_shortage = uvmexp.freetarg - uvmexp.free; 939 } 940 941 uvmpdpol_balancequeue(swap_shortage); 942 } 943 944 /* 945 * uvm_reclaimable: decide whether to wait for pagedaemon. 946 * 947 * => return TRUE if it seems to be worth to do uvm_wait. 948 * 949 * XXX should be tunable. 950 * XXX should consider pools, etc? 951 */ 952 953 boolean_t 954 uvm_reclaimable(void) 955 { 956 int filepages; 957 int active, inactive; 958 959 /* 960 * if swap is not full, no problem. 961 */ 962 963 if (!uvm_swapisfull()) { 964 return TRUE; 965 } 966 967 /* 968 * file-backed pages can be reclaimed even when swap is full. 969 * if we have more than 1/16 of pageable memory or 5MB, try to reclaim. 970 * 971 * XXX assume the worst case, ie. all wired pages are file-backed. 972 * 973 * XXX should consider about other reclaimable memory. 974 * XXX ie. pools, traditional buffer cache. 975 */ 976 977 filepages = uvmexp.filepages + uvmexp.execpages - uvmexp.wired; 978 uvm_estimatepageable(&active, &inactive); 979 if (filepages >= MIN((active + inactive) >> 4, 980 5 * 1024 * 1024 >> PAGE_SHIFT)) { 981 return TRUE; 982 } 983 984 /* 985 * kill the process, fail allocation, etc.. 986 */ 987 988 return FALSE; 989 } 990 991 void 992 uvm_estimatepageable(int *active, int *inactive) 993 { 994 995 uvmpdpol_estimatepageable(active, inactive); 996 } 997