1 /* $NetBSD: uvm_pdaemon.c,v 1.80 2006/11/01 10:18:27 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 1.80 2006/11/01 10:18:27 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 86 #include <uvm/uvm.h> 87 #include <uvm/uvm_pdpolicy.h> 88 89 /* 90 * UVMPD_NUMDIRTYREACTS is how many dirty pages the pagedaemon will reactivate 91 * in a pass thru the inactive list when swap is full. the value should be 92 * "small"... if it's too large we'll cycle the active pages thru the inactive 93 * queue too quickly to for them to be referenced and avoid being freed. 94 */ 95 96 #define UVMPD_NUMDIRTYREACTS 16 97 98 99 /* 100 * local prototypes 101 */ 102 103 static void uvmpd_scan(void); 104 static void uvmpd_scan_queue(void); 105 static void uvmpd_tune(void); 106 107 /* 108 * XXX hack to avoid hangs when large processes fork. 109 */ 110 int uvm_extrapages; 111 112 /* 113 * uvm_wait: wait (sleep) for the page daemon to free some pages 114 * 115 * => should be called with all locks released 116 * => should _not_ be called by the page daemon (to avoid deadlock) 117 */ 118 119 void 120 uvm_wait(const char *wmsg) 121 { 122 int timo = 0; 123 int s = splbio(); 124 125 /* 126 * check for page daemon going to sleep (waiting for itself) 127 */ 128 129 if (curproc == uvm.pagedaemon_proc && uvmexp.paging == 0) { 130 /* 131 * now we have a problem: the pagedaemon wants to go to 132 * sleep until it frees more memory. but how can it 133 * free more memory if it is asleep? that is a deadlock. 134 * we have two options: 135 * [1] panic now 136 * [2] put a timeout on the sleep, thus causing the 137 * pagedaemon to only pause (rather than sleep forever) 138 * 139 * note that option [2] will only help us if we get lucky 140 * and some other process on the system breaks the deadlock 141 * by exiting or freeing memory (thus allowing the pagedaemon 142 * to continue). for now we panic if DEBUG is defined, 143 * otherwise we hope for the best with option [2] (better 144 * yet, this should never happen in the first place!). 145 */ 146 147 printf("pagedaemon: deadlock detected!\n"); 148 timo = hz >> 3; /* set timeout */ 149 #if defined(DEBUG) 150 /* DEBUG: panic so we can debug it */ 151 panic("pagedaemon deadlock"); 152 #endif 153 } 154 155 simple_lock(&uvm.pagedaemon_lock); 156 wakeup(&uvm.pagedaemon); /* wake the daemon! */ 157 UVM_UNLOCK_AND_WAIT(&uvmexp.free, &uvm.pagedaemon_lock, FALSE, wmsg, 158 timo); 159 160 splx(s); 161 } 162 163 /* 164 * uvm_kick_pdaemon: perform checks to determine if we need to 165 * give the pagedaemon a nudge, and do so if necessary. 166 */ 167 168 void 169 uvm_kick_pdaemon(void) 170 { 171 172 if (uvmexp.free + uvmexp.paging < uvmexp.freemin || 173 (uvmexp.free + uvmexp.paging < uvmexp.freetarg && 174 uvmpdpol_needsscan_p())) { 175 wakeup(&uvm.pagedaemon); 176 } 177 } 178 179 /* 180 * uvmpd_tune: tune paging parameters 181 * 182 * => called when ever memory is added (or removed?) to the system 183 * => caller must call with page queues locked 184 */ 185 186 static void 187 uvmpd_tune(void) 188 { 189 UVMHIST_FUNC("uvmpd_tune"); UVMHIST_CALLED(pdhist); 190 191 uvmexp.freemin = uvmexp.npages / 20; 192 193 /* between 16k and 256k */ 194 /* XXX: what are these values good for? */ 195 uvmexp.freemin = MAX(uvmexp.freemin, (16*1024) >> PAGE_SHIFT); 196 uvmexp.freemin = MIN(uvmexp.freemin, (256*1024) >> PAGE_SHIFT); 197 198 /* Make sure there's always a user page free. */ 199 if (uvmexp.freemin < uvmexp.reserve_kernel + 1) 200 uvmexp.freemin = uvmexp.reserve_kernel + 1; 201 202 uvmexp.freetarg = (uvmexp.freemin * 4) / 3; 203 if (uvmexp.freetarg <= uvmexp.freemin) 204 uvmexp.freetarg = uvmexp.freemin + 1; 205 206 uvmexp.freetarg += uvm_extrapages; 207 uvm_extrapages = 0; 208 209 uvmexp.wiredmax = uvmexp.npages / 3; 210 UVMHIST_LOG(pdhist, "<- done, freemin=%d, freetarg=%d, wiredmax=%d", 211 uvmexp.freemin, uvmexp.freetarg, uvmexp.wiredmax, 0); 212 } 213 214 /* 215 * uvm_pageout: the main loop for the pagedaemon 216 */ 217 218 void 219 uvm_pageout(void *arg) 220 { 221 int bufcnt, npages = 0; 222 int extrapages = 0; 223 UVMHIST_FUNC("uvm_pageout"); UVMHIST_CALLED(pdhist); 224 225 UVMHIST_LOG(pdhist,"<starting uvm pagedaemon>", 0, 0, 0, 0); 226 227 /* 228 * ensure correct priority and set paging parameters... 229 */ 230 231 uvm.pagedaemon_proc = curproc; 232 uvm_lock_pageq(); 233 npages = uvmexp.npages; 234 uvmpd_tune(); 235 uvm_unlock_pageq(); 236 237 /* 238 * main loop 239 */ 240 241 for (;;) { 242 simple_lock(&uvm.pagedaemon_lock); 243 244 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 245 UVM_UNLOCK_AND_WAIT(&uvm.pagedaemon, 246 &uvm.pagedaemon_lock, FALSE, "pgdaemon", 0); 247 uvmexp.pdwoke++; 248 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 249 250 /* 251 * now lock page queues and recompute inactive count 252 */ 253 254 uvm_lock_pageq(); 255 if (npages != uvmexp.npages || extrapages != uvm_extrapages) { 256 npages = uvmexp.npages; 257 extrapages = uvm_extrapages; 258 uvmpd_tune(); 259 } 260 261 uvmpdpol_tune(); 262 263 /* 264 * Estimate a hint. Note that bufmem are returned to 265 * system only when entire pool page is empty. 266 */ 267 bufcnt = uvmexp.freetarg - uvmexp.free; 268 if (bufcnt < 0) 269 bufcnt = 0; 270 271 UVMHIST_LOG(pdhist," free/ftarg=%d/%d", 272 uvmexp.free, uvmexp.freetarg, 0,0); 273 274 /* 275 * scan if needed 276 */ 277 278 if (uvmexp.free + uvmexp.paging < uvmexp.freetarg || 279 uvmpdpol_needsscan_p()) { 280 uvmpd_scan(); 281 } 282 283 /* 284 * if there's any free memory to be had, 285 * wake up any waiters. 286 */ 287 288 if (uvmexp.free > uvmexp.reserve_kernel || 289 uvmexp.paging == 0) { 290 wakeup(&uvmexp.free); 291 } 292 293 /* 294 * scan done. unlock page queues (the only lock we are holding) 295 */ 296 297 uvm_unlock_pageq(); 298 299 buf_drain(bufcnt << PAGE_SHIFT); 300 301 /* 302 * drain pool resources now that we're not holding any locks 303 */ 304 305 pool_drain(0); 306 307 /* 308 * free any cached u-areas we don't need 309 */ 310 uvm_uarea_drain(TRUE); 311 312 } 313 /*NOTREACHED*/ 314 } 315 316 317 /* 318 * uvm_aiodone_daemon: main loop for the aiodone daemon. 319 */ 320 321 void 322 uvm_aiodone_daemon(void *arg) 323 { 324 int s, free; 325 struct buf *bp, *nbp; 326 UVMHIST_FUNC("uvm_aiodoned"); UVMHIST_CALLED(pdhist); 327 328 for (;;) { 329 330 /* 331 * carefully attempt to go to sleep (without losing "wakeups"!). 332 * we need splbio because we want to make sure the aio_done list 333 * is totally empty before we go to sleep. 334 */ 335 336 s = splbio(); 337 simple_lock(&uvm.aiodoned_lock); 338 if (TAILQ_FIRST(&uvm.aio_done) == NULL) { 339 UVMHIST_LOG(pdhist," <<SLEEPING>>",0,0,0,0); 340 UVM_UNLOCK_AND_WAIT(&uvm.aiodoned, 341 &uvm.aiodoned_lock, FALSE, "aiodoned", 0); 342 UVMHIST_LOG(pdhist," <<WOKE UP>>",0,0,0,0); 343 344 /* relock aiodoned_lock, still at splbio */ 345 simple_lock(&uvm.aiodoned_lock); 346 } 347 348 /* 349 * check for done aio structures 350 */ 351 352 bp = TAILQ_FIRST(&uvm.aio_done); 353 if (bp) { 354 TAILQ_INIT(&uvm.aio_done); 355 } 356 357 simple_unlock(&uvm.aiodoned_lock); 358 splx(s); 359 360 /* 361 * process each i/o that's done. 362 */ 363 364 free = uvmexp.free; 365 while (bp != NULL) { 366 nbp = TAILQ_NEXT(bp, b_freelist); 367 (*bp->b_iodone)(bp); 368 bp = nbp; 369 } 370 if (free <= uvmexp.reserve_kernel) { 371 s = uvm_lock_fpageq(); 372 wakeup(&uvm.pagedaemon); 373 uvm_unlock_fpageq(s); 374 } else { 375 simple_lock(&uvm.pagedaemon_lock); 376 wakeup(&uvmexp.free); 377 simple_unlock(&uvm.pagedaemon_lock); 378 } 379 } 380 } 381 382 /* 383 * uvmpd_trylockowner: trylock the page's owner. 384 * 385 * => called with pageq locked. 386 * => resolve orphaned O->A loaned page. 387 * => return the locked simplelock on success. otherwise, return NULL. 388 */ 389 390 struct simplelock * 391 uvmpd_trylockowner(struct vm_page *pg) 392 { 393 struct uvm_object *uobj = pg->uobject; 394 struct simplelock *slock; 395 396 UVM_LOCK_ASSERT_PAGEQ(); 397 if (uobj != NULL) { 398 slock = &uobj->vmobjlock; 399 } else { 400 struct vm_anon *anon = pg->uanon; 401 402 KASSERT(anon != NULL); 403 slock = &anon->an_lock; 404 } 405 406 if (!simple_lock_try(slock)) { 407 return NULL; 408 } 409 410 if (uobj == NULL) { 411 412 /* 413 * set PQ_ANON if it isn't set already. 414 */ 415 416 if ((pg->pqflags & PQ_ANON) == 0) { 417 KASSERT(pg->loan_count > 0); 418 pg->loan_count--; 419 pg->pqflags |= PQ_ANON; 420 /* anon now owns it */ 421 } 422 } 423 424 return slock; 425 } 426 427 #if defined(VMSWAP) 428 struct swapcluster { 429 int swc_slot; 430 int swc_nallocated; 431 int swc_nused; 432 struct vm_page *swc_pages[howmany(MAXPHYS, MIN_PAGE_SIZE)]; 433 }; 434 435 static void 436 swapcluster_init(struct swapcluster *swc) 437 { 438 439 swc->swc_slot = 0; 440 } 441 442 static int 443 swapcluster_allocslots(struct swapcluster *swc) 444 { 445 int slot; 446 int npages; 447 448 if (swc->swc_slot != 0) { 449 return 0; 450 } 451 452 /* Even with strange MAXPHYS, the shift 453 implicitly rounds down to a page. */ 454 npages = MAXPHYS >> PAGE_SHIFT; 455 slot = uvm_swap_alloc(&npages, TRUE); 456 if (slot == 0) { 457 return ENOMEM; 458 } 459 swc->swc_slot = slot; 460 swc->swc_nallocated = npages; 461 swc->swc_nused = 0; 462 463 return 0; 464 } 465 466 static int 467 swapcluster_add(struct swapcluster *swc, struct vm_page *pg) 468 { 469 int slot; 470 struct uvm_object *uobj; 471 472 KASSERT(swc->swc_slot != 0); 473 KASSERT(swc->swc_nused < swc->swc_nallocated); 474 KASSERT((pg->pqflags & PQ_SWAPBACKED) != 0); 475 476 slot = swc->swc_slot + swc->swc_nused; 477 uobj = pg->uobject; 478 if (uobj == NULL) { 479 LOCK_ASSERT(simple_lock_held(&pg->uanon->an_lock)); 480 pg->uanon->an_swslot = slot; 481 } else { 482 int result; 483 484 LOCK_ASSERT(simple_lock_held(&uobj->vmobjlock)); 485 result = uao_set_swslot(uobj, pg->offset >> PAGE_SHIFT, slot); 486 if (result == -1) { 487 return ENOMEM; 488 } 489 } 490 swc->swc_pages[swc->swc_nused] = pg; 491 swc->swc_nused++; 492 493 return 0; 494 } 495 496 static void 497 swapcluster_flush(struct swapcluster *swc, boolean_t now) 498 { 499 int slot; 500 int nused; 501 int nallocated; 502 int error; 503 504 if (swc->swc_slot == 0) { 505 return; 506 } 507 KASSERT(swc->swc_nused <= swc->swc_nallocated); 508 509 slot = swc->swc_slot; 510 nused = swc->swc_nused; 511 nallocated = swc->swc_nallocated; 512 513 /* 514 * if this is the final pageout we could have a few 515 * unused swap blocks. if so, free them now. 516 */ 517 518 if (nused < nallocated) { 519 if (!now) { 520 return; 521 } 522 uvm_swap_free(slot + nused, nallocated - nused); 523 } 524 525 /* 526 * now start the pageout. 527 */ 528 529 uvmexp.pdpageouts++; 530 error = uvm_swap_put(slot, swc->swc_pages, nused, 0); 531 KASSERT(error == 0); 532 533 /* 534 * zero swslot to indicate that we are 535 * no longer building a swap-backed cluster. 536 */ 537 538 swc->swc_slot = 0; 539 } 540 541 /* 542 * uvmpd_dropswap: free any swap allocated to this page. 543 * 544 * => called with owner locked. 545 * => return TRUE if a page had an associated slot. 546 */ 547 548 static boolean_t 549 uvmpd_dropswap(struct vm_page *pg) 550 { 551 boolean_t result = FALSE; 552 struct vm_anon *anon = pg->uanon; 553 554 if ((pg->pqflags & PQ_ANON) && anon->an_swslot) { 555 uvm_swap_free(anon->an_swslot, 1); 556 anon->an_swslot = 0; 557 pg->flags &= ~PG_CLEAN; 558 result = TRUE; 559 } else if (pg->pqflags & PQ_AOBJ) { 560 int slot = uao_set_swslot(pg->uobject, 561 pg->offset >> PAGE_SHIFT, 0); 562 if (slot) { 563 uvm_swap_free(slot, 1); 564 pg->flags &= ~PG_CLEAN; 565 result = TRUE; 566 } 567 } 568 569 return result; 570 } 571 572 /* 573 * uvmpd_trydropswap: try to free any swap allocated to this page. 574 * 575 * => return TRUE if a slot is successfully freed. 576 */ 577 578 boolean_t 579 uvmpd_trydropswap(struct vm_page *pg) 580 { 581 struct simplelock *slock; 582 boolean_t result; 583 584 if ((pg->flags & PG_BUSY) != 0) { 585 return FALSE; 586 } 587 588 /* 589 * lock the page's owner. 590 */ 591 592 slock = uvmpd_trylockowner(pg); 593 if (slock == NULL) { 594 return FALSE; 595 } 596 597 /* 598 * skip this page if it's busy. 599 */ 600 601 if ((pg->flags & PG_BUSY) != 0) { 602 simple_unlock(slock); 603 return FALSE; 604 } 605 606 result = uvmpd_dropswap(pg); 607 608 simple_unlock(slock); 609 610 return result; 611 } 612 613 #endif /* defined(VMSWAP) */ 614 615 /* 616 * uvmpd_scan_queue: scan an replace candidate list for pages 617 * to clean or free. 618 * 619 * => called with page queues locked 620 * => we work on meeting our free target by converting inactive pages 621 * into free pages. 622 * => we handle the building of swap-backed clusters 623 */ 624 625 static void 626 uvmpd_scan_queue(void) 627 { 628 struct vm_page *p; 629 struct uvm_object *uobj; 630 struct vm_anon *anon; 631 #if defined(VMSWAP) 632 struct swapcluster swc; 633 #endif /* defined(VMSWAP) */ 634 int dirtyreacts; 635 struct simplelock *slock; 636 UVMHIST_FUNC("uvmpd_scan_queue"); UVMHIST_CALLED(pdhist); 637 638 /* 639 * swslot is non-zero if we are building a swap cluster. we want 640 * to stay in the loop while we have a page to scan or we have 641 * a swap-cluster to build. 642 */ 643 644 #if defined(VMSWAP) 645 swapcluster_init(&swc); 646 #endif /* defined(VMSWAP) */ 647 648 dirtyreacts = 0; 649 uvmpdpol_scaninit(); 650 651 while (/* CONSTCOND */ 1) { 652 653 /* 654 * see if we've met the free target. 655 */ 656 657 if (uvmexp.free + uvmexp.paging >= uvmexp.freetarg << 2 || 658 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 659 UVMHIST_LOG(pdhist," met free target: " 660 "exit loop", 0, 0, 0, 0); 661 break; 662 } 663 664 p = uvmpdpol_selectvictim(); 665 if (p == NULL) { 666 break; 667 } 668 KASSERT(uvmpdpol_pageisqueued_p(p)); 669 KASSERT(p->wire_count == 0); 670 671 /* 672 * we are below target and have a new page to consider. 673 */ 674 675 anon = p->uanon; 676 uobj = p->uobject; 677 678 /* 679 * first we attempt to lock the object that this page 680 * belongs to. if our attempt fails we skip on to 681 * the next page (no harm done). it is important to 682 * "try" locking the object as we are locking in the 683 * wrong order (pageq -> object) and we don't want to 684 * deadlock. 685 * 686 * the only time we expect to see an ownerless page 687 * (i.e. a page with no uobject and !PQ_ANON) is if an 688 * anon has loaned a page from a uvm_object and the 689 * uvm_object has dropped the ownership. in that 690 * case, the anon can "take over" the loaned page 691 * and make it its own. 692 */ 693 694 slock = uvmpd_trylockowner(p); 695 if (slock == NULL) { 696 continue; 697 } 698 if (p->flags & PG_BUSY) { 699 simple_unlock(slock); 700 uvmexp.pdbusy++; 701 continue; 702 } 703 704 /* does the page belong to an object? */ 705 if (uobj != NULL) { 706 uvmexp.pdobscan++; 707 } else { 708 #if defined(VMSWAP) 709 KASSERT(anon != NULL); 710 uvmexp.pdanscan++; 711 #else /* defined(VMSWAP) */ 712 panic("%s: anon", __func__); 713 #endif /* defined(VMSWAP) */ 714 } 715 716 717 /* 718 * we now have the object and the page queues locked. 719 * if the page is not swap-backed, call the object's 720 * pager to flush and free the page. 721 */ 722 723 #if defined(READAHEAD_STATS) 724 if ((p->pqflags & PQ_READAHEAD) != 0) { 725 p->pqflags &= ~PQ_READAHEAD; 726 uvm_ra_miss.ev_count++; 727 } 728 #endif /* defined(READAHEAD_STATS) */ 729 730 if ((p->pqflags & PQ_SWAPBACKED) == 0) { 731 uvm_unlock_pageq(); 732 (void) (uobj->pgops->pgo_put)(uobj, p->offset, 733 p->offset + PAGE_SIZE, PGO_CLEANIT|PGO_FREE); 734 uvm_lock_pageq(); 735 continue; 736 } 737 738 /* 739 * the page is swap-backed. remove all the permissions 740 * from the page so we can sync the modified info 741 * without any race conditions. if the page is clean 742 * we can free it now and continue. 743 */ 744 745 pmap_page_protect(p, VM_PROT_NONE); 746 if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) { 747 p->flags &= ~(PG_CLEAN); 748 } 749 if (p->flags & PG_CLEAN) { 750 int slot; 751 int pageidx; 752 753 pageidx = p->offset >> PAGE_SHIFT; 754 uvm_pagefree(p); 755 uvmexp.pdfreed++; 756 757 /* 758 * for anons, we need to remove the page 759 * from the anon ourselves. for aobjs, 760 * pagefree did that for us. 761 */ 762 763 if (anon) { 764 KASSERT(anon->an_swslot != 0); 765 anon->an_page = NULL; 766 slot = anon->an_swslot; 767 } else { 768 slot = uao_find_swslot(uobj, pageidx); 769 } 770 simple_unlock(slock); 771 772 if (slot > 0) { 773 /* this page is now only in swap. */ 774 simple_lock(&uvm.swap_data_lock); 775 KASSERT(uvmexp.swpgonly < uvmexp.swpginuse); 776 uvmexp.swpgonly++; 777 simple_unlock(&uvm.swap_data_lock); 778 } 779 continue; 780 } 781 782 #if defined(VMSWAP) 783 /* 784 * this page is dirty, skip it if we'll have met our 785 * free target when all the current pageouts complete. 786 */ 787 788 if (uvmexp.free + uvmexp.paging > uvmexp.freetarg << 2) { 789 simple_unlock(slock); 790 continue; 791 } 792 793 /* 794 * free any swap space allocated to the page since 795 * we'll have to write it again with its new data. 796 */ 797 798 uvmpd_dropswap(p); 799 800 /* 801 * if all pages in swap are only in swap, 802 * the swap space is full and we can't page out 803 * any more swap-backed pages. reactivate this page 804 * so that we eventually cycle all pages through 805 * the inactive queue. 806 */ 807 808 if (uvm_swapisfull()) { 809 dirtyreacts++; 810 uvm_pageactivate(p); 811 simple_unlock(slock); 812 continue; 813 } 814 815 /* 816 * start new swap pageout cluster (if necessary). 817 */ 818 819 if (swapcluster_allocslots(&swc)) { 820 simple_unlock(slock); 821 dirtyreacts++; /* XXX */ 822 continue; 823 } 824 825 /* 826 * at this point, we're definitely going reuse this 827 * page. mark the page busy and delayed-free. 828 * we should remove the page from the page queues 829 * so we don't ever look at it again. 830 * adjust counters and such. 831 */ 832 833 p->flags |= PG_BUSY; 834 UVM_PAGE_OWN(p, "scan_queue"); 835 836 p->flags |= PG_PAGEOUT; 837 uvmexp.paging++; 838 uvm_pagedequeue(p); 839 840 uvmexp.pgswapout++; 841 uvm_unlock_pageq(); 842 843 /* 844 * add the new page to the cluster. 845 */ 846 847 if (swapcluster_add(&swc, p)) { 848 p->flags &= ~(PG_BUSY|PG_PAGEOUT); 849 UVM_PAGE_OWN(p, NULL); 850 uvm_lock_pageq(); 851 uvmexp.paging--; 852 dirtyreacts++; 853 uvm_pageactivate(p); 854 simple_unlock(slock); 855 continue; 856 } 857 simple_unlock(slock); 858 859 swapcluster_flush(&swc, FALSE); 860 uvm_lock_pageq(); 861 862 /* 863 * the pageout is in progress. bump counters and set up 864 * for the next loop. 865 */ 866 867 uvmexp.pdpending++; 868 869 #else /* defined(VMSWAP) */ 870 uvm_pageactivate(p); 871 simple_unlock(slock); 872 #endif /* defined(VMSWAP) */ 873 } 874 875 #if defined(VMSWAP) 876 uvm_unlock_pageq(); 877 swapcluster_flush(&swc, TRUE); 878 uvm_lock_pageq(); 879 #endif /* defined(VMSWAP) */ 880 } 881 882 /* 883 * uvmpd_scan: scan the page queues and attempt to meet our targets. 884 * 885 * => called with pageq's locked 886 */ 887 888 static void 889 uvmpd_scan(void) 890 { 891 int swap_shortage, pages_freed; 892 UVMHIST_FUNC("uvmpd_scan"); UVMHIST_CALLED(pdhist); 893 894 uvmexp.pdrevs++; 895 896 #ifndef __SWAP_BROKEN 897 898 /* 899 * swap out some processes if we are below our free target. 900 * we need to unlock the page queues for this. 901 */ 902 903 if (uvmexp.free < uvmexp.freetarg && uvmexp.nswapdev != 0) { 904 uvmexp.pdswout++; 905 UVMHIST_LOG(pdhist," free %d < target %d: swapout", 906 uvmexp.free, uvmexp.freetarg, 0, 0); 907 uvm_unlock_pageq(); 908 uvm_swapout_threads(); 909 uvm_lock_pageq(); 910 911 } 912 #endif 913 914 /* 915 * now we want to work on meeting our targets. first we work on our 916 * free target by converting inactive pages into free pages. then 917 * we work on meeting our inactive target by converting active pages 918 * to inactive ones. 919 */ 920 921 UVMHIST_LOG(pdhist, " starting 'free' loop",0,0,0,0); 922 923 pages_freed = uvmexp.pdfreed; 924 uvmpd_scan_queue(); 925 pages_freed = uvmexp.pdfreed - pages_freed; 926 927 /* 928 * detect if we're not going to be able to page anything out 929 * until we free some swap resources from active pages. 930 */ 931 932 swap_shortage = 0; 933 if (uvmexp.free < uvmexp.freetarg && 934 uvmexp.swpginuse >= uvmexp.swpgavail && 935 !uvm_swapisfull() && 936 pages_freed == 0) { 937 swap_shortage = uvmexp.freetarg - uvmexp.free; 938 } 939 940 uvmpdpol_balancequeue(swap_shortage); 941 } 942 943 /* 944 * uvm_reclaimable: decide whether to wait for pagedaemon. 945 * 946 * => return TRUE if it seems to be worth to do uvm_wait. 947 * 948 * XXX should be tunable. 949 * XXX should consider pools, etc? 950 */ 951 952 boolean_t 953 uvm_reclaimable(void) 954 { 955 int filepages; 956 int active, inactive; 957 958 /* 959 * if swap is not full, no problem. 960 */ 961 962 if (!uvm_swapisfull()) { 963 return TRUE; 964 } 965 966 /* 967 * file-backed pages can be reclaimed even when swap is full. 968 * if we have more than 1/16 of pageable memory or 5MB, try to reclaim. 969 * 970 * XXX assume the worst case, ie. all wired pages are file-backed. 971 * 972 * XXX should consider about other reclaimable memory. 973 * XXX ie. pools, traditional buffer cache. 974 */ 975 976 filepages = uvmexp.filepages + uvmexp.execpages - uvmexp.wired; 977 uvm_estimatepageable(&active, &inactive); 978 if (filepages >= MIN((active + inactive) >> 4, 979 5 * 1024 * 1024 >> PAGE_SHIFT)) { 980 return TRUE; 981 } 982 983 /* 984 * kill the process, fail allocation, etc.. 985 */ 986 987 return FALSE; 988 } 989 990 void 991 uvm_estimatepageable(int *active, int *inactive) 992 { 993 994 uvmpdpol_estimatepageable(active, inactive); 995 } 996