1 /* $OpenBSD: uvm_pdaemon.c,v 1.96 2022/04/11 16:43:49 mpi Exp $ */ 2 /* $NetBSD: uvm_pdaemon.c,v 1.23 2000/08/20 10:24:14 bjh21 Exp $ */ 3 4 /* 5 * Copyright (c) 1997 Charles D. Cranor and Washington University. 6 * Copyright (c) 1991, 1993, The Regents of the University of California. 7 * 8 * All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * The Mach Operating System project at Carnegie-Mellon University. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)vm_pageout.c 8.5 (Berkeley) 2/14/94 38 * from: Id: uvm_pdaemon.c,v 1.1.2.32 1998/02/06 05:26:30 chs Exp 39 * 40 * 41 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 42 * All rights reserved. 43 * 44 * Permission to use, copy, modify and distribute this software and 45 * its documentation is hereby granted, provided that both the copyright 46 * notice and this permission notice appear in all copies of the 47 * software, derivative works or modified versions, and any portions 48 * thereof, and that both notices appear in supporting documentation. 49 * 50 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 51 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 52 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 53 * 54 * Carnegie Mellon requests users of this software to return to 55 * 56 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 57 * School of Computer Science 58 * Carnegie Mellon University 59 * Pittsburgh PA 15213-3890 60 * 61 * any improvements or extensions that they make and grant Carnegie the 62 * rights to redistribute these changes. 63 */ 64 65 /* 66 * uvm_pdaemon.c: the page daemon 67 */ 68 69 #include <sys/param.h> 70 #include <sys/systm.h> 71 #include <sys/kernel.h> 72 #include <sys/pool.h> 73 #include <sys/proc.h> 74 #include <sys/buf.h> 75 #include <sys/mount.h> 76 #include <sys/atomic.h> 77 78 #ifdef HIBERNATE 79 #include <sys/hibernate.h> 80 #endif 81 82 #include <uvm/uvm.h> 83 84 #include "drm.h" 85 86 #if NDRM > 0 87 extern void drmbackoff(long); 88 #endif 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 void uvmpd_scan(void); 105 boolean_t uvmpd_scan_inactive(struct pglist *); 106 void uvmpd_tune(void); 107 void uvmpd_drop(struct pglist *); 108 109 /* 110 * uvm_wait: wait (sleep) for the page daemon to free some pages 111 * 112 * => should be called with all locks released 113 * => should _not_ be called by the page daemon (to avoid deadlock) 114 */ 115 116 void 117 uvm_wait(const char *wmsg) 118 { 119 uint64_t timo = INFSLP; 120 121 #ifdef DIAGNOSTIC 122 if (curproc == &proc0) 123 panic("%s: cannot sleep for memory during boot", __func__); 124 #endif 125 126 /* 127 * check for page daemon going to sleep (waiting for itself) 128 */ 129 if (curproc == uvm.pagedaemon_proc) { 130 printf("uvm_wait emergency bufbackoff\n"); 131 if (bufbackoff(NULL, 4) == 0) 132 return; 133 /* 134 * now we have a problem: the pagedaemon wants to go to 135 * sleep until it frees more memory. but how can it 136 * free more memory if it is asleep? that is a deadlock. 137 * we have two options: 138 * [1] panic now 139 * [2] put a timeout on the sleep, thus causing the 140 * pagedaemon to only pause (rather than sleep forever) 141 * 142 * note that option [2] will only help us if we get lucky 143 * and some other process on the system breaks the deadlock 144 * by exiting or freeing memory (thus allowing the pagedaemon 145 * to continue). for now we panic if DEBUG is defined, 146 * otherwise we hope for the best with option [2] (better 147 * yet, this should never happen in the first place!). 148 */ 149 150 printf("pagedaemon: deadlock detected!\n"); 151 timo = MSEC_TO_NSEC(125); /* set timeout */ 152 #if defined(DEBUG) 153 /* DEBUG: panic so we can debug it */ 154 panic("pagedaemon deadlock"); 155 #endif 156 } 157 158 uvm_lock_fpageq(); 159 wakeup(&uvm.pagedaemon); /* wake the daemon! */ 160 msleep_nsec(&uvmexp.free, &uvm.fpageqlock, PVM | PNORELOCK, wmsg, timo); 161 } 162 163 /* 164 * uvmpd_tune: tune paging parameters 165 * 166 * => called whenever memory is added to (or removed from?) the system 167 * => caller must call with page queues locked 168 */ 169 170 void 171 uvmpd_tune(void) 172 { 173 174 uvmexp.freemin = uvmexp.npages / 30; 175 176 /* between 16k and 512k */ 177 /* XXX: what are these values good for? */ 178 uvmexp.freemin = max(uvmexp.freemin, (16*1024) >> PAGE_SHIFT); 179 #if 0 180 uvmexp.freemin = min(uvmexp.freemin, (512*1024) >> PAGE_SHIFT); 181 #endif 182 183 /* Make sure there's always a user page free. */ 184 if (uvmexp.freemin < uvmexp.reserve_kernel + 1) 185 uvmexp.freemin = uvmexp.reserve_kernel + 1; 186 187 uvmexp.freetarg = (uvmexp.freemin * 4) / 3; 188 if (uvmexp.freetarg <= uvmexp.freemin) 189 uvmexp.freetarg = uvmexp.freemin + 1; 190 191 /* uvmexp.inactarg: computed in main daemon loop */ 192 193 uvmexp.wiredmax = uvmexp.npages / 3; 194 } 195 196 /* 197 * Indicate to the page daemon that a nowait call failed and it should 198 * recover at least some memory in the most restricted region (assumed 199 * to be dma_constraint). 200 */ 201 volatile int uvm_nowait_failed; 202 203 /* 204 * uvm_pageout: the main loop for the pagedaemon 205 */ 206 void 207 uvm_pageout(void *arg) 208 { 209 struct uvm_constraint_range constraint; 210 struct uvm_pmalloc *pma; 211 int npages = 0; 212 213 /* ensure correct priority and set paging parameters... */ 214 uvm.pagedaemon_proc = curproc; 215 (void) spl0(); 216 uvm_lock_pageq(); 217 npages = uvmexp.npages; 218 uvmpd_tune(); 219 uvm_unlock_pageq(); 220 221 for (;;) { 222 long size; 223 224 uvm_lock_fpageq(); 225 if (!uvm_nowait_failed && TAILQ_EMPTY(&uvm.pmr_control.allocs)) { 226 msleep_nsec(&uvm.pagedaemon, &uvm.fpageqlock, PVM, 227 "pgdaemon", INFSLP); 228 uvmexp.pdwoke++; 229 } 230 231 if ((pma = TAILQ_FIRST(&uvm.pmr_control.allocs)) != NULL) { 232 pma->pm_flags |= UVM_PMA_BUSY; 233 constraint = pma->pm_constraint; 234 } else { 235 if (uvm_nowait_failed) { 236 /* 237 * XXX realisticly, this is what our 238 * nowait callers probably care about 239 */ 240 constraint = dma_constraint; 241 uvm_nowait_failed = 0; 242 } else 243 constraint = no_constraint; 244 } 245 246 uvm_unlock_fpageq(); 247 248 /* 249 * now lock page queues and recompute inactive count 250 */ 251 uvm_lock_pageq(); 252 if (npages != uvmexp.npages) { /* check for new pages? */ 253 npages = uvmexp.npages; 254 uvmpd_tune(); 255 } 256 257 uvmexp.inactarg = (uvmexp.active + uvmexp.inactive) / 3; 258 if (uvmexp.inactarg <= uvmexp.freetarg) { 259 uvmexp.inactarg = uvmexp.freetarg + 1; 260 } 261 262 /* Reclaim pages from the buffer cache if possible. */ 263 size = 0; 264 if (pma != NULL) 265 size += pma->pm_size >> PAGE_SHIFT; 266 if (uvmexp.free - BUFPAGES_DEFICIT < uvmexp.freetarg) 267 size += uvmexp.freetarg - (uvmexp.free - 268 BUFPAGES_DEFICIT); 269 if (size == 0) 270 size = 16; /* XXX */ 271 uvm_unlock_pageq(); 272 (void) bufbackoff(&constraint, size * 2); 273 #if NDRM > 0 274 drmbackoff(size * 2); 275 #endif 276 uvm_lock_pageq(); 277 278 /* 279 * scan if needed 280 */ 281 if (pma != NULL || 282 ((uvmexp.free - BUFPAGES_DEFICIT) < uvmexp.freetarg) || 283 ((uvmexp.inactive + BUFPAGES_INACT) < uvmexp.inactarg)) { 284 uvmpd_scan(); 285 } 286 287 /* 288 * if there's any free memory to be had, 289 * wake up any waiters. 290 */ 291 uvm_lock_fpageq(); 292 if (uvmexp.free > uvmexp.reserve_kernel || 293 uvmexp.paging == 0) { 294 wakeup(&uvmexp.free); 295 } 296 297 if (pma != NULL) { 298 /* 299 * XXX If UVM_PMA_FREED isn't set, no pages 300 * were freed. Should we set UVM_PMA_FAIL in 301 * that case? 302 */ 303 pma->pm_flags &= ~UVM_PMA_BUSY; 304 if (pma->pm_flags & UVM_PMA_FREED) { 305 pma->pm_flags &= ~UVM_PMA_LINKED; 306 TAILQ_REMOVE(&uvm.pmr_control.allocs, pma, 307 pmq); 308 wakeup(pma); 309 } 310 } 311 uvm_unlock_fpageq(); 312 313 /* 314 * scan done. unlock page queues (the only lock we are holding) 315 */ 316 uvm_unlock_pageq(); 317 318 sched_pause(yield); 319 } 320 /*NOTREACHED*/ 321 } 322 323 324 /* 325 * uvm_aiodone_daemon: main loop for the aiodone daemon. 326 */ 327 void 328 uvm_aiodone_daemon(void *arg) 329 { 330 int s, free; 331 struct buf *bp, *nbp; 332 333 uvm.aiodoned_proc = curproc; 334 335 for (;;) { 336 /* 337 * Check for done aio structures. If we've got structures to 338 * process, do so. Otherwise sleep while avoiding races. 339 */ 340 mtx_enter(&uvm.aiodoned_lock); 341 while ((bp = TAILQ_FIRST(&uvm.aio_done)) == NULL) 342 msleep_nsec(&uvm.aiodoned, &uvm.aiodoned_lock, 343 PVM, "aiodoned", INFSLP); 344 /* Take the list for ourselves. */ 345 TAILQ_INIT(&uvm.aio_done); 346 mtx_leave(&uvm.aiodoned_lock); 347 348 /* process each i/o that's done. */ 349 free = uvmexp.free; 350 while (bp != NULL) { 351 if (bp->b_flags & B_PDAEMON) { 352 uvmexp.paging -= bp->b_bufsize >> PAGE_SHIFT; 353 } 354 nbp = TAILQ_NEXT(bp, b_freelist); 355 s = splbio(); /* b_iodone must by called at splbio */ 356 (*bp->b_iodone)(bp); 357 splx(s); 358 bp = nbp; 359 360 sched_pause(yield); 361 } 362 uvm_lock_fpageq(); 363 wakeup(free <= uvmexp.reserve_kernel ? &uvm.pagedaemon : 364 &uvmexp.free); 365 uvm_unlock_fpageq(); 366 } 367 } 368 369 370 371 /* 372 * uvmpd_scan_inactive: scan an inactive list for pages to clean or free. 373 * 374 * => called with page queues locked 375 * => we work on meeting our free target by converting inactive pages 376 * into free pages. 377 * => we handle the building of swap-backed clusters 378 * => we return TRUE if we are exiting because we met our target 379 */ 380 381 boolean_t 382 uvmpd_scan_inactive(struct pglist *pglst) 383 { 384 boolean_t retval = FALSE; /* assume we haven't hit target */ 385 int free, result; 386 struct vm_page *p, *nextpg; 387 struct uvm_object *uobj; 388 struct vm_page *pps[MAXBSIZE >> PAGE_SHIFT], **ppsp; 389 int npages; 390 struct vm_page *swpps[MAXBSIZE >> PAGE_SHIFT]; /* XXX: see below */ 391 int swnpages, swcpages; /* XXX: see below */ 392 int swslot; 393 struct vm_anon *anon; 394 boolean_t swap_backed; 395 vaddr_t start; 396 int dirtyreacts; 397 398 /* 399 * note: we currently keep swap-backed pages on a separate inactive 400 * list from object-backed pages. however, merging the two lists 401 * back together again hasn't been ruled out. thus, we keep our 402 * swap cluster in "swpps" rather than in pps (allows us to mix 403 * clustering types in the event of a mixed inactive queue). 404 */ 405 /* 406 * swslot is non-zero if we are building a swap cluster. we want 407 * to stay in the loop while we have a page to scan or we have 408 * a swap-cluster to build. 409 */ 410 swslot = 0; 411 swnpages = swcpages = 0; 412 free = 0; 413 dirtyreacts = 0; 414 415 for (p = TAILQ_FIRST(pglst); p != NULL || swslot != 0; p = nextpg) { 416 /* 417 * note that p can be NULL iff we have traversed the whole 418 * list and need to do one final swap-backed clustered pageout. 419 */ 420 uobj = NULL; 421 anon = NULL; 422 423 if (p) { 424 /* 425 * update our copy of "free" and see if we've met 426 * our target 427 */ 428 free = uvmexp.free - BUFPAGES_DEFICIT; 429 430 if (free + uvmexp.paging >= uvmexp.freetarg << 2 || 431 dirtyreacts == UVMPD_NUMDIRTYREACTS) { 432 retval = TRUE; 433 434 if (swslot == 0) { 435 /* exit now if no swap-i/o pending */ 436 break; 437 } 438 439 /* set p to null to signal final swap i/o */ 440 p = NULL; 441 } 442 } 443 444 if (p) { /* if (we have a new page to consider) */ 445 /* 446 * we are below target and have a new page to consider. 447 */ 448 uvmexp.pdscans++; 449 nextpg = TAILQ_NEXT(p, pageq); 450 451 if (p->pg_flags & PQ_ANON) { 452 anon = p->uanon; 453 KASSERT(anon != NULL); 454 if (rw_enter(anon->an_lock, 455 RW_WRITE|RW_NOSLEEP)) { 456 /* lock failed, skip this page */ 457 continue; 458 } 459 /* 460 * move referenced pages back to active queue 461 * and skip to next page. 462 */ 463 if (pmap_is_referenced(p)) { 464 uvm_pageactivate(p); 465 rw_exit(anon->an_lock); 466 uvmexp.pdreact++; 467 continue; 468 } 469 if (p->pg_flags & PG_BUSY) { 470 rw_exit(anon->an_lock); 471 uvmexp.pdbusy++; 472 /* someone else owns page, skip it */ 473 continue; 474 } 475 uvmexp.pdanscan++; 476 } else { 477 uobj = p->uobject; 478 KASSERT(uobj != NULL); 479 if (rw_enter(uobj->vmobjlock, 480 RW_WRITE|RW_NOSLEEP)) { 481 /* lock failed, skip this page */ 482 continue; 483 } 484 /* 485 * move referenced pages back to active queue 486 * and skip to next page. 487 */ 488 if (pmap_is_referenced(p)) { 489 uvm_pageactivate(p); 490 rw_exit(uobj->vmobjlock); 491 uvmexp.pdreact++; 492 continue; 493 } 494 if (p->pg_flags & PG_BUSY) { 495 rw_exit(uobj->vmobjlock); 496 uvmexp.pdbusy++; 497 /* someone else owns page, skip it */ 498 continue; 499 } 500 uvmexp.pdobscan++; 501 } 502 503 /* 504 * we now have the page queues locked. 505 * the page is not busy. if the page is clean we 506 * can free it now and continue. 507 */ 508 if (p->pg_flags & PG_CLEAN) { 509 if (p->pg_flags & PQ_SWAPBACKED) { 510 /* this page now lives only in swap */ 511 atomic_inc_int(&uvmexp.swpgonly); 512 } 513 514 /* zap all mappings with pmap_page_protect... */ 515 pmap_page_protect(p, PROT_NONE); 516 uvm_pagefree(p); 517 uvmexp.pdfreed++; 518 519 if (anon) { 520 521 /* 522 * an anonymous page can only be clean 523 * if it has backing store assigned. 524 */ 525 526 KASSERT(anon->an_swslot != 0); 527 528 /* remove from object */ 529 anon->an_page = NULL; 530 rw_exit(anon->an_lock); 531 } else { 532 rw_exit(uobj->vmobjlock); 533 } 534 continue; 535 } 536 537 /* 538 * this page is dirty, skip it if we'll have met our 539 * free target when all the current pageouts complete. 540 */ 541 if (free + uvmexp.paging > uvmexp.freetarg << 2) { 542 if (anon) { 543 rw_exit(anon->an_lock); 544 } else { 545 rw_exit(uobj->vmobjlock); 546 } 547 continue; 548 } 549 550 /* 551 * this page is dirty, but we can't page it out 552 * since all pages in swap are only in swap. 553 * reactivate it so that we eventually cycle 554 * all pages thru the inactive queue. 555 */ 556 if ((p->pg_flags & PQ_SWAPBACKED) && uvm_swapisfull()) { 557 dirtyreacts++; 558 uvm_pageactivate(p); 559 if (anon) { 560 rw_exit(anon->an_lock); 561 } else { 562 rw_exit(uobj->vmobjlock); 563 } 564 continue; 565 } 566 567 /* 568 * if the page is swap-backed and dirty and swap space 569 * is full, free any swap allocated to the page 570 * so that other pages can be paged out. 571 */ 572 KASSERT(uvmexp.swpginuse <= uvmexp.swpages); 573 if ((p->pg_flags & PQ_SWAPBACKED) && 574 uvmexp.swpginuse == uvmexp.swpages) { 575 576 if ((p->pg_flags & PQ_ANON) && 577 p->uanon->an_swslot) { 578 uvm_swap_free(p->uanon->an_swslot, 1); 579 p->uanon->an_swslot = 0; 580 } 581 if (p->pg_flags & PQ_AOBJ) { 582 uao_dropswap(p->uobject, 583 p->offset >> PAGE_SHIFT); 584 } 585 } 586 587 /* 588 * the page we are looking at is dirty. we must 589 * clean it before it can be freed. to do this we 590 * first mark the page busy so that no one else will 591 * touch the page. we write protect all the mappings 592 * of the page so that no one touches it while it is 593 * in I/O. 594 */ 595 596 swap_backed = ((p->pg_flags & PQ_SWAPBACKED) != 0); 597 atomic_setbits_int(&p->pg_flags, PG_BUSY); 598 UVM_PAGE_OWN(p, "scan_inactive"); 599 pmap_page_protect(p, PROT_READ); 600 uvmexp.pgswapout++; 601 602 /* 603 * for swap-backed pages we need to (re)allocate 604 * swap space. 605 */ 606 if (swap_backed) { 607 /* free old swap slot (if any) */ 608 if (anon) { 609 if (anon->an_swslot) { 610 uvm_swap_free(anon->an_swslot, 611 1); 612 anon->an_swslot = 0; 613 } 614 } else { 615 uao_dropswap(uobj, 616 p->offset >> PAGE_SHIFT); 617 } 618 619 /* start new cluster (if necessary) */ 620 if (swslot == 0) { 621 swnpages = MAXBSIZE >> PAGE_SHIFT; 622 swslot = uvm_swap_alloc(&swnpages, 623 TRUE); 624 if (swslot == 0) { 625 /* no swap? give up! */ 626 atomic_clearbits_int( 627 &p->pg_flags, 628 PG_BUSY); 629 UVM_PAGE_OWN(p, NULL); 630 if (anon) 631 rw_exit(anon->an_lock); 632 else 633 rw_exit( 634 uobj->vmobjlock); 635 continue; 636 } 637 swcpages = 0; /* cluster is empty */ 638 } 639 640 /* add block to cluster */ 641 swpps[swcpages] = p; 642 if (anon) 643 anon->an_swslot = swslot + swcpages; 644 else 645 uao_set_swslot(uobj, 646 p->offset >> PAGE_SHIFT, 647 swslot + swcpages); 648 swcpages++; 649 } 650 } else { 651 /* if p == NULL we must be doing a last swap i/o */ 652 swap_backed = TRUE; 653 } 654 655 /* 656 * now consider doing the pageout. 657 * 658 * for swap-backed pages, we do the pageout if we have either 659 * filled the cluster (in which case (swnpages == swcpages) or 660 * run out of pages (p == NULL). 661 * 662 * for object pages, we always do the pageout. 663 */ 664 if (swap_backed) { 665 if (p) { /* if we just added a page to cluster */ 666 if (anon) 667 rw_exit(anon->an_lock); 668 else 669 rw_exit(uobj->vmobjlock); 670 671 /* cluster not full yet? */ 672 if (swcpages < swnpages) 673 continue; 674 } 675 676 /* starting I/O now... set up for it */ 677 npages = swcpages; 678 ppsp = swpps; 679 /* for swap-backed pages only */ 680 start = (vaddr_t) swslot; 681 682 /* if this is final pageout we could have a few 683 * extra swap blocks */ 684 if (swcpages < swnpages) { 685 uvm_swap_free(swslot + swcpages, 686 (swnpages - swcpages)); 687 } 688 } else { 689 /* normal object pageout */ 690 ppsp = pps; 691 npages = sizeof(pps) / sizeof(struct vm_page *); 692 /* not looked at because PGO_ALLPAGES is set */ 693 start = 0; 694 } 695 696 /* 697 * now do the pageout. 698 * 699 * for swap_backed pages we have already built the cluster. 700 * for !swap_backed pages, uvm_pager_put will call the object's 701 * "make put cluster" function to build a cluster on our behalf. 702 * 703 * we pass the PGO_PDFREECLUST flag to uvm_pager_put to instruct 704 * it to free the cluster pages for us on a successful I/O (it 705 * always does this for un-successful I/O requests). this 706 * allows us to do clustered pageout without having to deal 707 * with cluster pages at this level. 708 * 709 * note locking semantics of uvm_pager_put with PGO_PDFREECLUST: 710 * IN: locked: page queues 711 * OUT: locked: 712 * !locked: pageqs 713 */ 714 715 uvmexp.pdpageouts++; 716 result = uvm_pager_put(swap_backed ? NULL : uobj, p, 717 &ppsp, &npages, PGO_ALLPAGES|PGO_PDFREECLUST, start, 0); 718 719 /* 720 * if we did i/o to swap, zero swslot to indicate that we are 721 * no longer building a swap-backed cluster. 722 */ 723 724 if (swap_backed) 725 swslot = 0; /* done with this cluster */ 726 727 /* 728 * first, we check for VM_PAGER_PEND which means that the 729 * async I/O is in progress and the async I/O done routine 730 * will clean up after us. in this case we move on to the 731 * next page. 732 * 733 * there is a very remote chance that the pending async i/o can 734 * finish _before_ we get here. if that happens, our page "p" 735 * may no longer be on the inactive queue. so we verify this 736 * when determining the next page (starting over at the head if 737 * we've lost our inactive page). 738 */ 739 740 if (result == VM_PAGER_PEND) { 741 uvmexp.paging += npages; 742 uvm_lock_pageq(); 743 uvmexp.pdpending++; 744 if (p) { 745 if (p->pg_flags & PQ_INACTIVE) 746 nextpg = TAILQ_NEXT(p, pageq); 747 else 748 nextpg = TAILQ_FIRST(pglst); 749 } else { 750 nextpg = NULL; 751 } 752 continue; 753 } 754 755 /* clean up "p" if we have one */ 756 if (p) { 757 /* 758 * the I/O request to "p" is done and uvm_pager_put 759 * has freed any cluster pages it may have allocated 760 * during I/O. all that is left for us to do is 761 * clean up page "p" (which is still PG_BUSY). 762 * 763 * our result could be one of the following: 764 * VM_PAGER_OK: successful pageout 765 * 766 * VM_PAGER_AGAIN: tmp resource shortage, we skip 767 * to next page 768 * VM_PAGER_{FAIL,ERROR,BAD}: an error. we 769 * "reactivate" page to get it out of the way (it 770 * will eventually drift back into the inactive 771 * queue for a retry). 772 * VM_PAGER_UNLOCK: should never see this as it is 773 * only valid for "get" operations 774 */ 775 776 /* relock p's object: page queues not lock yet, so 777 * no need for "try" */ 778 779 /* !swap_backed case: already locked... */ 780 if (swap_backed) { 781 if (anon) 782 rw_enter(anon->an_lock, RW_WRITE); 783 else 784 rw_enter(uobj->vmobjlock, RW_WRITE); 785 } 786 787 #ifdef DIAGNOSTIC 788 if (result == VM_PAGER_UNLOCK) 789 panic("pagedaemon: pageout returned " 790 "invalid 'unlock' code"); 791 #endif 792 793 /* handle PG_WANTED now */ 794 if (p->pg_flags & PG_WANTED) 795 wakeup(p); 796 797 atomic_clearbits_int(&p->pg_flags, PG_BUSY|PG_WANTED); 798 UVM_PAGE_OWN(p, NULL); 799 800 /* released during I/O? Can only happen for anons */ 801 if (p->pg_flags & PG_RELEASED) { 802 KASSERT(anon != NULL); 803 /* 804 * remove page so we can get nextpg, 805 * also zero out anon so we don't use 806 * it after the free. 807 */ 808 anon->an_page = NULL; 809 p->uanon = NULL; 810 811 rw_exit(anon->an_lock); 812 uvm_anfree(anon); /* kills anon */ 813 pmap_page_protect(p, PROT_NONE); 814 anon = NULL; 815 uvm_lock_pageq(); 816 nextpg = TAILQ_NEXT(p, pageq); 817 /* free released page */ 818 uvm_pagefree(p); 819 } else { /* page was not released during I/O */ 820 uvm_lock_pageq(); 821 nextpg = TAILQ_NEXT(p, pageq); 822 if (result != VM_PAGER_OK) { 823 /* pageout was a failure... */ 824 if (result != VM_PAGER_AGAIN) 825 uvm_pageactivate(p); 826 pmap_clear_reference(p); 827 /* XXXCDC: if (swap_backed) FREE p's 828 * swap block? */ 829 } else { 830 /* pageout was a success... */ 831 pmap_clear_reference(p); 832 pmap_clear_modify(p); 833 atomic_setbits_int(&p->pg_flags, 834 PG_CLEAN); 835 } 836 } 837 838 /* 839 * drop object lock (if there is an object left). do 840 * a safety check of nextpg to make sure it is on the 841 * inactive queue (it should be since PG_BUSY pages on 842 * the inactive queue can't be re-queued [note: not 843 * true for active queue]). 844 */ 845 if (anon) 846 rw_exit(anon->an_lock); 847 else if (uobj) 848 rw_exit(uobj->vmobjlock); 849 850 if (nextpg && (nextpg->pg_flags & PQ_INACTIVE) == 0) { 851 nextpg = TAILQ_FIRST(pglst); /* reload! */ 852 } 853 } else { 854 /* 855 * if p is null in this loop, make sure it stays null 856 * in the next loop. 857 */ 858 nextpg = NULL; 859 860 /* 861 * lock page queues here just so they're always locked 862 * at the end of the loop. 863 */ 864 uvm_lock_pageq(); 865 } 866 } 867 return (retval); 868 } 869 870 /* 871 * uvmpd_scan: scan the page queues and attempt to meet our targets. 872 * 873 * => called with pageq's locked 874 */ 875 876 void 877 uvmpd_scan(void) 878 { 879 int free, inactive_shortage, swap_shortage, pages_freed; 880 struct vm_page *p, *nextpg; 881 struct uvm_object *uobj; 882 boolean_t got_it; 883 884 MUTEX_ASSERT_LOCKED(&uvm.pageqlock); 885 886 uvmexp.pdrevs++; /* counter */ 887 uobj = NULL; 888 889 /* 890 * get current "free" page count 891 */ 892 free = uvmexp.free - BUFPAGES_DEFICIT; 893 894 #ifndef __SWAP_BROKEN 895 /* 896 * swap out some processes if we are below our free target. 897 * we need to unlock the page queues for this. 898 */ 899 if (free < uvmexp.freetarg) { 900 uvmexp.pdswout++; 901 uvm_unlock_pageq(); 902 uvm_swapout_threads(); 903 uvm_lock_pageq(); 904 } 905 #endif 906 907 /* 908 * now we want to work on meeting our targets. first we work on our 909 * free target by converting inactive pages into free pages. then 910 * we work on meeting our inactive target by converting active pages 911 * to inactive ones. 912 */ 913 914 /* 915 * alternate starting queue between swap and object based on the 916 * low bit of uvmexp.pdrevs (which we bump by one each call). 917 */ 918 got_it = FALSE; 919 pages_freed = uvmexp.pdfreed; /* XXX - int */ 920 if ((uvmexp.pdrevs & 1) != 0 && uvmexp.nswapdev != 0) 921 got_it = uvmpd_scan_inactive(&uvm.page_inactive_swp); 922 if (!got_it) 923 got_it = uvmpd_scan_inactive(&uvm.page_inactive_obj); 924 if (!got_it && (uvmexp.pdrevs & 1) == 0 && uvmexp.nswapdev != 0) 925 (void) uvmpd_scan_inactive(&uvm.page_inactive_swp); 926 pages_freed = uvmexp.pdfreed - pages_freed; 927 928 /* 929 * we have done the scan to get free pages. now we work on meeting 930 * our inactive target. 931 */ 932 inactive_shortage = uvmexp.inactarg - uvmexp.inactive - BUFPAGES_INACT; 933 934 /* 935 * detect if we're not going to be able to page anything out 936 * until we free some swap resources from active pages. 937 */ 938 swap_shortage = 0; 939 if (uvmexp.free < uvmexp.freetarg && 940 uvmexp.swpginuse == uvmexp.swpages && 941 !uvm_swapisfull() && 942 pages_freed == 0) { 943 swap_shortage = uvmexp.freetarg - uvmexp.free; 944 } 945 946 for (p = TAILQ_FIRST(&uvm.page_active); 947 p != NULL && (inactive_shortage > 0 || swap_shortage > 0); 948 p = nextpg) { 949 nextpg = TAILQ_NEXT(p, pageq); 950 951 /* skip this page if it's busy. */ 952 if (p->pg_flags & PG_BUSY) 953 continue; 954 955 if (p->pg_flags & PQ_ANON) { 956 KASSERT(p->uanon != NULL); 957 if (rw_enter(p->uanon->an_lock, RW_WRITE|RW_NOSLEEP)) 958 continue; 959 } else { 960 KASSERT(p->uobject != NULL); 961 if (rw_enter(p->uobject->vmobjlock, 962 RW_WRITE|RW_NOSLEEP)) 963 continue; 964 } 965 966 /* 967 * if there's a shortage of swap, free any swap allocated 968 * to this page so that other pages can be paged out. 969 */ 970 if (swap_shortage > 0) { 971 if ((p->pg_flags & PQ_ANON) && p->uanon->an_swslot) { 972 uvm_swap_free(p->uanon->an_swslot, 1); 973 p->uanon->an_swslot = 0; 974 atomic_clearbits_int(&p->pg_flags, PG_CLEAN); 975 swap_shortage--; 976 } 977 if (p->pg_flags & PQ_AOBJ) { 978 int slot = uao_set_swslot(p->uobject, 979 p->offset >> PAGE_SHIFT, 0); 980 if (slot) { 981 uvm_swap_free(slot, 1); 982 atomic_clearbits_int(&p->pg_flags, 983 PG_CLEAN); 984 swap_shortage--; 985 } 986 } 987 } 988 989 /* 990 * deactivate this page if there's a shortage of 991 * inactive pages. 992 */ 993 if (inactive_shortage > 0) { 994 pmap_page_protect(p, PROT_NONE); 995 /* no need to check wire_count as pg is "active" */ 996 uvm_pagedeactivate(p); 997 uvmexp.pddeact++; 998 inactive_shortage--; 999 } 1000 if (p->pg_flags & PQ_ANON) 1001 rw_exit(p->uanon->an_lock); 1002 else 1003 rw_exit(p->uobject->vmobjlock); 1004 } 1005 } 1006 1007 #ifdef HIBERNATE 1008 1009 /* 1010 * uvmpd_drop: drop clean pages from list 1011 */ 1012 void 1013 uvmpd_drop(struct pglist *pglst) 1014 { 1015 struct vm_page *p, *nextpg; 1016 1017 for (p = TAILQ_FIRST(pglst); p != NULL; p = nextpg) { 1018 nextpg = TAILQ_NEXT(p, pageq); 1019 1020 if (p->pg_flags & PQ_ANON || p->uobject == NULL) 1021 continue; 1022 1023 if (p->pg_flags & PG_BUSY) 1024 continue; 1025 1026 if (p->pg_flags & PG_CLEAN) { 1027 struct uvm_object * uobj = p->uobject; 1028 1029 rw_enter(uobj->vmobjlock, RW_WRITE); 1030 uvm_lock_pageq(); 1031 /* 1032 * we now have the page queues locked. 1033 * the page is not busy. if the page is clean we 1034 * can free it now and continue. 1035 */ 1036 if (p->pg_flags & PG_CLEAN) { 1037 if (p->pg_flags & PQ_SWAPBACKED) { 1038 /* this page now lives only in swap */ 1039 atomic_inc_int(&uvmexp.swpgonly); 1040 } 1041 1042 /* zap all mappings with pmap_page_protect... */ 1043 pmap_page_protect(p, PROT_NONE); 1044 uvm_pagefree(p); 1045 } 1046 uvm_unlock_pageq(); 1047 rw_exit(uobj->vmobjlock); 1048 } 1049 } 1050 } 1051 1052 void 1053 uvmpd_hibernate(void) 1054 { 1055 uvmpd_drop(&uvm.page_inactive_swp); 1056 uvmpd_drop(&uvm.page_inactive_obj); 1057 uvmpd_drop(&uvm.page_active); 1058 } 1059 1060 #endif 1061