1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 2010,2019 The DragonFly Project. All rights reserved. 5 * 6 * This code is derived from software contributed to The DragonFly Project 7 * by Matthew Dillon <dillon@backplane.com> 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 3. Neither the name of The DragonFly Project nor the names of its 20 * contributors may be used to endorse or promote products derived 21 * from this software without specific, prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 26 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 27 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 29 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 30 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 31 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 32 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 /* 38 * Implement the swapcache daemon. When enabled swap is assumed to be 39 * configured on a fast storage device such as a SSD. Swap is assigned 40 * to clean vnode-backed pages in the inactive queue, clustered by object 41 * if possible, and written out. The swap assignment sticks around even 42 * after the underlying pages have been recycled. 43 * 44 * The daemon manages write bandwidth based on sysctl settings to control 45 * wear on the SSD. 46 * 47 * The vnode strategy code will check for the swap assignments and divert 48 * reads to the swap device when the data is present in the swapcache. 49 * 50 * This operates on both regular files and the block device vnodes used by 51 * filesystems to manage meta-data. 52 */ 53 54 #include <sys/param.h> 55 #include <sys/systm.h> 56 #include <sys/kernel.h> 57 #include <sys/proc.h> 58 #include <sys/kthread.h> 59 #include <sys/resourcevar.h> 60 #include <sys/signalvar.h> 61 #include <sys/vnode.h> 62 #include <sys/vmmeter.h> 63 #include <sys/sysctl.h> 64 #include <sys/eventhandler.h> 65 66 #include <vm/vm.h> 67 #include <vm/vm_param.h> 68 #include <sys/lock.h> 69 #include <vm/vm_object.h> 70 #include <vm/vm_page.h> 71 #include <vm/vm_map.h> 72 #include <vm/vm_pageout.h> 73 #include <vm/vm_pager.h> 74 #include <vm/swap_pager.h> 75 #include <vm/vm_extern.h> 76 77 #include <sys/spinlock2.h> 78 #include <vm/vm_page2.h> 79 80 struct swmarker { 81 struct vm_object dummy_obj; 82 struct vm_object *save_obj; 83 vm_ooffset_t save_off; 84 }; 85 86 typedef struct swmarker swmarker_t; 87 88 /* the kernel process "vm_pageout"*/ 89 static int vm_swapcached_flush (vm_page_t m, int isblkdev); 90 static int vm_swapcache_test(vm_page_t m); 91 static int vm_swapcache_writing_heuristic(void); 92 static int vm_swapcache_writing(vm_page_t marker, int count, int scount); 93 static void vm_swapcache_cleaning(swmarker_t *marker, 94 struct vm_object_hash **swindexp); 95 static void vm_swapcache_movemarker(swmarker_t *marker, 96 struct vm_object_hash *swindex, vm_object_t object); 97 struct thread *swapcached_thread; 98 99 SYSCTL_NODE(_vm, OID_AUTO, swapcache, CTLFLAG_RW, NULL, NULL); 100 101 int vm_swapcache_read_enable; 102 static long vm_swapcache_wtrigger; 103 static int vm_swapcache_sleep; 104 static int vm_swapcache_maxscan = PQ_L2_SIZE * 8; 105 static int vm_swapcache_maxlaunder = PQ_L2_SIZE * 4; 106 static int vm_swapcache_data_enable = 0; 107 static int vm_swapcache_meta_enable = 0; 108 static int vm_swapcache_maxswappct = 75; 109 static int vm_swapcache_hysteresis; 110 static int vm_swapcache_min_hysteresis; 111 int vm_swapcache_use_chflags = 0; /* require chflags cache */ 112 static int64_t vm_swapcache_minburst = 10000000LL; /* 10MB */ 113 static int64_t vm_swapcache_curburst = 4000000000LL; /* 4G after boot */ 114 static int64_t vm_swapcache_maxburst = 2000000000LL; /* 2G nominal max */ 115 static int64_t vm_swapcache_accrate = 100000LL; /* 100K/s */ 116 static int64_t vm_swapcache_write_count; 117 static int64_t vm_swapcache_maxfilesize; 118 static int64_t vm_swapcache_cleanperobj = 16*1024*1024; 119 120 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxlaunder, 121 CTLFLAG_RW, &vm_swapcache_maxlaunder, 0, ""); 122 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxscan, 123 CTLFLAG_RW, &vm_swapcache_maxscan, 0, ""); 124 125 SYSCTL_INT(_vm_swapcache, OID_AUTO, data_enable, 126 CTLFLAG_RW, &vm_swapcache_data_enable, 0, ""); 127 SYSCTL_INT(_vm_swapcache, OID_AUTO, meta_enable, 128 CTLFLAG_RW, &vm_swapcache_meta_enable, 0, ""); 129 SYSCTL_INT(_vm_swapcache, OID_AUTO, read_enable, 130 CTLFLAG_RW, &vm_swapcache_read_enable, 0, ""); 131 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxswappct, 132 CTLFLAG_RW, &vm_swapcache_maxswappct, 0, ""); 133 SYSCTL_INT(_vm_swapcache, OID_AUTO, hysteresis, 134 CTLFLAG_RD, &vm_swapcache_hysteresis, 0, ""); 135 SYSCTL_INT(_vm_swapcache, OID_AUTO, min_hysteresis, 136 CTLFLAG_RW, &vm_swapcache_min_hysteresis, 0, ""); 137 SYSCTL_INT(_vm_swapcache, OID_AUTO, use_chflags, 138 CTLFLAG_RW, &vm_swapcache_use_chflags, 0, ""); 139 140 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, minburst, 141 CTLFLAG_RW, &vm_swapcache_minburst, 0, ""); 142 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, curburst, 143 CTLFLAG_RW, &vm_swapcache_curburst, 0, ""); 144 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, maxburst, 145 CTLFLAG_RW, &vm_swapcache_maxburst, 0, ""); 146 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, maxfilesize, 147 CTLFLAG_RW, &vm_swapcache_maxfilesize, 0, ""); 148 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, accrate, 149 CTLFLAG_RW, &vm_swapcache_accrate, 0, ""); 150 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, write_count, 151 CTLFLAG_RW, &vm_swapcache_write_count, 0, ""); 152 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, cleanperobj, 153 CTLFLAG_RW, &vm_swapcache_cleanperobj, 0, ""); 154 155 #define SWAPMAX(adj) \ 156 ((int64_t)vm_swap_max * (vm_swapcache_maxswappct + (adj)) / 100) 157 158 /* 159 * When shutting down the machine we want to stop swapcache operation 160 * immediately so swap is not accessed after devices have been shuttered. 161 */ 162 static void 163 shutdown_swapcache(void *arg __unused) 164 { 165 vm_swapcache_read_enable = 0; 166 vm_swapcache_data_enable = 0; 167 vm_swapcache_meta_enable = 0; 168 wakeup(&vm_swapcache_sleep); /* shortcut 5-second wait */ 169 } 170 171 /* 172 * vm_swapcached is the high level pageout daemon. 173 * 174 * No requirements. 175 */ 176 static void 177 vm_swapcached_thread(void) 178 { 179 enum { SWAPC_WRITING, SWAPC_CLEANING } state = SWAPC_WRITING; 180 enum { SWAPB_BURSTING, SWAPB_RECOVERING } burst = SWAPB_BURSTING; 181 static struct vm_page page_marker[PQ_L2_SIZE]; 182 static swmarker_t swmarker; 183 static struct vm_object_hash *swindex; 184 int q; 185 186 /* 187 * Thread setup 188 */ 189 curthread->td_flags |= TDF_SYSTHREAD; 190 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 191 swapcached_thread, SHUTDOWN_PRI_FIRST); 192 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_swapcache, 193 NULL, SHUTDOWN_PRI_SECOND); 194 195 /* 196 * Initialize our marker for the inactive scan (SWAPC_WRITING) 197 */ 198 bzero(&page_marker, sizeof(page_marker)); 199 for (q = 0; q < PQ_L2_SIZE; ++q) { 200 page_marker[q].flags = PG_FICTITIOUS | PG_MARKER; 201 page_marker[q].busy_count = PBUSY_LOCKED; 202 page_marker[q].queue = PQ_INACTIVE + q; 203 page_marker[q].pc = q; 204 page_marker[q].wire_count = 1; 205 vm_page_queues_spin_lock(PQ_INACTIVE + q); 206 TAILQ_INSERT_HEAD( 207 &vm_page_queues[PQ_INACTIVE + q].pl, 208 &page_marker[q], pageq); 209 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 210 } 211 212 vm_swapcache_min_hysteresis = 1024; 213 vm_swapcache_hysteresis = vm_swapcache_min_hysteresis; 214 vm_swapcache_wtrigger = -vm_swapcache_hysteresis; 215 216 /* 217 * Initialize our marker for the vm_object scan (SWAPC_CLEANING) 218 */ 219 bzero(&swmarker, sizeof(swmarker)); 220 swmarker.dummy_obj.type = OBJT_MARKER; 221 swindex = &vm_object_hash[0]; 222 lwkt_gettoken(&swindex->token); 223 TAILQ_INSERT_HEAD(&swindex->list, &swmarker.dummy_obj, object_entry); 224 lwkt_reltoken(&swindex->token); 225 226 for (;;) { 227 int reached_end; 228 int scount; 229 int count; 230 231 /* 232 * Handle shutdown 233 */ 234 kproc_suspend_loop(); 235 236 /* 237 * Check every 5 seconds when not enabled or if no swap 238 * is present. 239 */ 240 if ((vm_swapcache_data_enable == 0 && 241 vm_swapcache_meta_enable == 0 && 242 vm_swap_cache_use <= SWAPMAX(0)) || 243 vm_swap_max == 0) { 244 tsleep(&vm_swapcache_sleep, 0, "csleep", hz * 5); 245 continue; 246 } 247 248 /* 249 * Polling rate when enabled is approximately 10 hz. 250 */ 251 tsleep(&vm_swapcache_sleep, 0, "csleep", hz / 10); 252 253 /* 254 * State hysteresis. Generate write activity up to 75% of 255 * swap, then clean out swap assignments down to 70%, then 256 * repeat. 257 */ 258 if (state == SWAPC_WRITING) { 259 if (vm_swap_cache_use > SWAPMAX(0)) 260 state = SWAPC_CLEANING; 261 } else { 262 if (vm_swap_cache_use < SWAPMAX(-10)) 263 state = SWAPC_WRITING; 264 } 265 266 /* 267 * We are allowed to continue accumulating burst value 268 * in either state. Allow the user to set curburst > maxburst 269 * for the initial load-in. 270 */ 271 if (vm_swapcache_curburst < vm_swapcache_maxburst) { 272 vm_swapcache_curburst += vm_swapcache_accrate / 10; 273 if (vm_swapcache_curburst > vm_swapcache_maxburst) 274 vm_swapcache_curburst = vm_swapcache_maxburst; 275 } 276 277 /* 278 * We don't want to nickle-and-dime the scan as that will 279 * create unnecessary fragmentation. The minimum burst 280 * is one-seconds worth of accumulation. 281 */ 282 if (state != SWAPC_WRITING) { 283 vm_swapcache_cleaning(&swmarker, &swindex); 284 continue; 285 } 286 if (vm_swapcache_curburst < vm_swapcache_accrate) 287 continue; 288 289 reached_end = 0; 290 count = vm_swapcache_maxlaunder / PQ_L2_SIZE + 2; 291 scount = vm_swapcache_maxscan / PQ_L2_SIZE + 2; 292 293 if (burst == SWAPB_BURSTING) { 294 if (vm_swapcache_writing_heuristic()) { 295 for (q = 0; q < PQ_L2_SIZE; ++q) { 296 reached_end += 297 vm_swapcache_writing( 298 &page_marker[q], 299 count, 300 scount); 301 } 302 } 303 if (vm_swapcache_curburst <= 0) 304 burst = SWAPB_RECOVERING; 305 } else if (vm_swapcache_curburst > vm_swapcache_minburst) { 306 if (vm_swapcache_writing_heuristic()) { 307 for (q = 0; q < PQ_L2_SIZE; ++q) { 308 reached_end += 309 vm_swapcache_writing( 310 &page_marker[q], 311 count, 312 scount); 313 } 314 } 315 burst = SWAPB_BURSTING; 316 } 317 if (reached_end == PQ_L2_SIZE) { 318 vm_swapcache_wtrigger = -vm_swapcache_hysteresis; 319 } 320 } 321 322 /* 323 * Cleanup (NOT REACHED) 324 */ 325 for (q = 0; q < PQ_L2_SIZE; ++q) { 326 vm_page_queues_spin_lock(PQ_INACTIVE + q); 327 TAILQ_REMOVE( 328 &vm_page_queues[PQ_INACTIVE + q].pl, 329 &page_marker[q], pageq); 330 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 331 } 332 333 lwkt_gettoken(&swindex->token); 334 TAILQ_REMOVE(&swindex->list, &swmarker.dummy_obj, object_entry); 335 lwkt_reltoken(&swindex->token); 336 } 337 338 static struct kproc_desc swpc_kp = { 339 "swapcached", 340 vm_swapcached_thread, 341 &swapcached_thread 342 }; 343 SYSINIT(swapcached, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start, &swpc_kp); 344 345 /* 346 * Deal with an overflow of the heuristic counter or if the user 347 * manually changes the hysteresis. 348 * 349 * Try to avoid small incremental pageouts by waiting for enough 350 * pages to buildup in the inactive queue to hopefully get a good 351 * burst in. This heuristic is bumped by the VM system and reset 352 * when our scan hits the end of the queue. 353 * 354 * Return TRUE if we need to take a writing pass. 355 */ 356 static int 357 vm_swapcache_writing_heuristic(void) 358 { 359 int hyst; 360 int q; 361 long adds; 362 363 hyst = vmstats.v_inactive_count / 4; 364 if (hyst < vm_swapcache_min_hysteresis) 365 hyst = vm_swapcache_min_hysteresis; 366 cpu_ccfence(); 367 vm_swapcache_hysteresis = hyst; 368 369 adds = 0; 370 for (q = PQ_INACTIVE; q < PQ_INACTIVE + PQ_L2_SIZE; ++q) { 371 adds += atomic_swap_long(&vm_page_queues[q].adds, 0); 372 } 373 vm_swapcache_wtrigger += adds; 374 if (vm_swapcache_wtrigger < -hyst) 375 vm_swapcache_wtrigger = -hyst; 376 return (vm_swapcache_wtrigger >= 0); 377 } 378 379 /* 380 * Take a writing pass on one of the inactive queues, return non-zero if 381 * we hit the end of the queue. 382 */ 383 static int 384 vm_swapcache_writing(vm_page_t marker, int count, int scount) 385 { 386 vm_object_t object; 387 struct vnode *vp; 388 vm_page_t m; 389 int isblkdev; 390 391 /* 392 * Scan the inactive queue from our marker to locate 393 * suitable pages to push to the swap cache. 394 * 395 * We are looking for clean vnode-backed pages. 396 */ 397 vm_page_queues_spin_lock(marker->queue); 398 while ((m = TAILQ_NEXT(marker, pageq)) != NULL && 399 count > 0 && scount-- > 0) { 400 KKASSERT(m->queue == marker->queue); 401 402 /* 403 * Stop using swap if paniced, dumping, or dumped. 404 * Don't try to write if our curburst has been exhausted. 405 */ 406 if (panicstr || dumping) 407 break; 408 if (vm_swapcache_curburst < 0) 409 break; 410 411 /* 412 * Move marker 413 */ 414 TAILQ_REMOVE( 415 &vm_page_queues[marker->queue].pl, marker, pageq); 416 TAILQ_INSERT_AFTER( 417 &vm_page_queues[marker->queue].pl, m, marker, pageq); 418 419 /* 420 * Ignore markers and ignore pages that already have a swap 421 * assignment. 422 */ 423 if (m->flags & (PG_MARKER | PG_SWAPPED)) 424 continue; 425 if (vm_page_busy_try(m, TRUE)) 426 continue; 427 vm_page_queues_spin_unlock(marker->queue); 428 429 if ((object = m->object) == NULL) { 430 vm_page_wakeup(m); 431 vm_page_queues_spin_lock(marker->queue); 432 continue; 433 } 434 vm_object_hold(object); 435 if (m->object != object) { 436 vm_object_drop(object); 437 vm_page_wakeup(m); 438 vm_page_queues_spin_lock(marker->queue); 439 continue; 440 } 441 if (vm_swapcache_test(m)) { 442 vm_object_drop(object); 443 vm_page_wakeup(m); 444 vm_page_queues_spin_lock(marker->queue); 445 continue; 446 } 447 448 vp = object->handle; 449 if (vp == NULL) { 450 vm_object_drop(object); 451 vm_page_wakeup(m); 452 vm_page_queues_spin_lock(marker->queue); 453 continue; 454 } 455 456 switch(vp->v_type) { 457 case VREG: 458 /* 459 * PG_NOTMETA generically means 'don't swapcache this', 460 * and HAMMER will set this for regular data buffers 461 * (and leave it unset for meta-data buffers) as 462 * appropriate when double buffering is enabled. 463 */ 464 if (m->flags & PG_NOTMETA) { 465 vm_object_drop(object); 466 vm_page_wakeup(m); 467 vm_page_queues_spin_lock(marker->queue); 468 continue; 469 } 470 471 /* 472 * If data_enable is 0 do not try to swapcache data. 473 * If use_chflags is set then only swapcache data for 474 * VSWAPCACHE marked vnodes, otherwise any vnode. 475 */ 476 if (vm_swapcache_data_enable == 0 || 477 ((vp->v_flag & VSWAPCACHE) == 0 && 478 vm_swapcache_use_chflags)) { 479 vm_object_drop(object); 480 vm_page_wakeup(m); 481 vm_page_queues_spin_lock(marker->queue); 482 continue; 483 } 484 if (vm_swapcache_maxfilesize && 485 object->size > 486 (vm_swapcache_maxfilesize >> PAGE_SHIFT)) { 487 vm_object_drop(object); 488 vm_page_wakeup(m); 489 vm_page_queues_spin_lock(marker->queue); 490 continue; 491 } 492 isblkdev = 0; 493 break; 494 case VCHR: 495 /* 496 * PG_NOTMETA generically means 'don't swapcache this', 497 * and HAMMER will set this for regular data buffers 498 * (and leave it unset for meta-data buffers) as 499 * appropriate when double buffering is enabled. 500 */ 501 if (m->flags & PG_NOTMETA) { 502 vm_object_drop(object); 503 vm_page_wakeup(m); 504 vm_page_queues_spin_lock(marker->queue); 505 continue; 506 } 507 if (vm_swapcache_meta_enable == 0) { 508 vm_object_drop(object); 509 vm_page_wakeup(m); 510 vm_page_queues_spin_lock(marker->queue); 511 continue; 512 } 513 isblkdev = 1; 514 break; 515 default: 516 vm_object_drop(object); 517 vm_page_wakeup(m); 518 vm_page_queues_spin_lock(marker->queue); 519 continue; 520 } 521 522 523 /* 524 * Assign swap and initiate I/O. 525 * 526 * (adjust for the --count which also occurs in the loop) 527 */ 528 count -= vm_swapcached_flush(m, isblkdev); 529 530 /* 531 * Setup for next loop using marker. 532 */ 533 vm_object_drop(object); 534 vm_page_queues_spin_lock(marker->queue); 535 } 536 537 /* 538 * The marker could wind up at the end, which is ok. If we hit the 539 * end of the list adjust the heuristic. 540 * 541 * Earlier inactive pages that were dirty and become clean 542 * are typically moved to the end of PQ_INACTIVE by virtue 543 * of vfs_vmio_release() when they become unwired from the 544 * buffer cache. 545 */ 546 vm_page_queues_spin_unlock(marker->queue); 547 548 /* 549 * m invalid but can be used to test for NULL 550 */ 551 return (m == NULL); 552 } 553 554 /* 555 * Flush the specified page using the swap_pager. The page 556 * must be busied by the caller and its disposition will become 557 * the responsibility of this function. 558 * 559 * Try to collect surrounding pages, including pages which may 560 * have already been assigned swap. Try to cluster within a 561 * contiguous aligned SMAP_META_PAGES (typ 16 x PAGE_SIZE) block 562 * to match what swap_pager_putpages() can do. 563 * 564 * We also want to try to match against the buffer cache blocksize 565 * but we don't really know what it is here. Since the buffer cache 566 * wires and unwires pages in groups the fact that we skip wired pages 567 * should be sufficient. 568 * 569 * Returns a count of pages we might have flushed (minimum 1) 570 */ 571 static 572 int 573 vm_swapcached_flush(vm_page_t m, int isblkdev) 574 { 575 vm_object_t object; 576 vm_page_t marray[SWAP_META_PAGES]; 577 vm_pindex_t basei; 578 int rtvals[SWAP_META_PAGES]; 579 int x; 580 int i; 581 int j; 582 int count; 583 int error; 584 585 vm_page_io_start(m); 586 vm_page_protect(m, VM_PROT_READ); 587 object = m->object; 588 vm_object_hold(object); 589 590 /* 591 * Try to cluster around (m), keeping in mind that the swap pager 592 * can only do SMAP_META_PAGES worth of continguous write. 593 */ 594 x = (int)m->pindex & SWAP_META_MASK; 595 marray[x] = m; 596 basei = m->pindex; 597 vm_page_wakeup(m); 598 599 for (i = x - 1; i >= 0; --i) { 600 m = vm_page_lookup_busy_try(object, basei - x + i, 601 TRUE, &error); 602 if (error || m == NULL) 603 break; 604 if (vm_swapcache_test(m)) { 605 vm_page_wakeup(m); 606 break; 607 } 608 if (isblkdev && (m->flags & PG_NOTMETA)) { 609 vm_page_wakeup(m); 610 break; 611 } 612 vm_page_io_start(m); 613 vm_page_protect(m, VM_PROT_READ); 614 if (m->queue - m->pc == PQ_CACHE) { 615 vm_page_unqueue_nowakeup(m); 616 vm_page_deactivate(m); 617 } 618 marray[i] = m; 619 vm_page_wakeup(m); 620 } 621 ++i; 622 623 for (j = x + 1; j < SWAP_META_PAGES; ++j) { 624 m = vm_page_lookup_busy_try(object, basei - x + j, 625 TRUE, &error); 626 if (error || m == NULL) 627 break; 628 if (vm_swapcache_test(m)) { 629 vm_page_wakeup(m); 630 break; 631 } 632 if (isblkdev && (m->flags & PG_NOTMETA)) { 633 vm_page_wakeup(m); 634 break; 635 } 636 vm_page_io_start(m); 637 vm_page_protect(m, VM_PROT_READ); 638 if (m->queue - m->pc == PQ_CACHE) { 639 vm_page_unqueue_nowakeup(m); 640 vm_page_deactivate(m); 641 } 642 marray[j] = m; 643 vm_page_wakeup(m); 644 } 645 646 count = j - i; 647 vm_object_pip_add(object, count); 648 swap_pager_putpages(object, marray + i, count, FALSE, rtvals + i); 649 vm_swapcache_write_count += count * PAGE_SIZE; 650 vm_swapcache_curburst -= count * PAGE_SIZE; 651 652 while (i < j) { 653 if (rtvals[i] != VM_PAGER_PEND) { 654 vm_page_busy_wait(marray[i], FALSE, "swppgfd"); 655 vm_page_io_finish(marray[i]); 656 vm_page_wakeup(marray[i]); 657 vm_object_pip_wakeup(object); 658 } 659 ++i; 660 } 661 vm_object_drop(object); 662 return(count); 663 } 664 665 /* 666 * Test whether a VM page is suitable for writing to the swapcache. 667 * Does not test m->queue, PG_MARKER, or PG_SWAPPED. 668 * 669 * Returns 0 on success, 1 on failure 670 */ 671 static int 672 vm_swapcache_test(vm_page_t m) 673 { 674 vm_object_t object; 675 676 if (m->flags & (PG_UNQUEUED | PG_FICTITIOUS)) 677 return(1); 678 if (m->hold_count || m->wire_count) 679 return(1); 680 if (m->valid != VM_PAGE_BITS_ALL) 681 return(1); 682 if (m->dirty & m->valid) 683 return(1); 684 if ((object = m->object) == NULL) 685 return(1); 686 if (object->type != OBJT_VNODE || 687 (object->flags & OBJ_DEAD)) { 688 return(1); 689 } 690 vm_page_test_dirty(m); 691 if (m->dirty & m->valid) 692 return(1); 693 return(0); 694 } 695 696 /* 697 * Cleaning pass. 698 * 699 * We clean whole objects up to 16MB 700 */ 701 static 702 void 703 vm_swapcache_cleaning(swmarker_t *marker, struct vm_object_hash **swindexp) 704 { 705 vm_object_t object; 706 struct vnode *vp; 707 int count; 708 int scount; 709 int n; 710 int didmove; 711 712 count = vm_swapcache_maxlaunder; 713 scount = vm_swapcache_maxscan; 714 715 /* 716 * Look for vnode objects 717 */ 718 lwkt_gettoken(&(*swindexp)->token); 719 720 didmove = 0; 721 outerloop: 722 while ((object = TAILQ_NEXT(&marker->dummy_obj, 723 object_entry)) != NULL) { 724 /* 725 * We have to skip markers. We cannot hold/drop marker 726 * objects! 727 */ 728 if (object->type == OBJT_MARKER) { 729 vm_swapcache_movemarker(marker, *swindexp, object); 730 didmove = 1; 731 continue; 732 } 733 734 /* 735 * Safety, or in case there are millions of VM objects 736 * without swapcache backing. 737 */ 738 if (--scount <= 0) 739 goto breakout; 740 741 /* 742 * We must hold the object before potentially yielding. 743 */ 744 vm_object_hold(object); 745 lwkt_yield(); 746 747 /* 748 * Only operate on live VNODE objects that are either 749 * VREG or VCHR (VCHR for meta-data). 750 */ 751 if ((object->type != OBJT_VNODE) || 752 ((object->flags & OBJ_DEAD) || 753 object->swblock_count == 0) || 754 ((vp = object->handle) == NULL) || 755 (vp->v_type != VREG && vp->v_type != VCHR)) { 756 vm_object_drop(object); 757 /* object may be invalid now */ 758 vm_swapcache_movemarker(marker, *swindexp, object); 759 didmove = 1; 760 continue; 761 } 762 763 /* 764 * Reset the object pindex stored in the marker if the 765 * working object has changed. 766 */ 767 if (marker->save_obj != object || didmove) { 768 marker->dummy_obj.size = 0; 769 marker->save_off = 0; 770 marker->save_obj = object; 771 didmove = 0; 772 } 773 774 /* 775 * Look for swblocks starting at our iterator. 776 * 777 * The swap_pager_condfree() function attempts to free 778 * swap space starting at the specified index. The index 779 * will be updated on return. The function will return 780 * a scan factor (NOT the number of blocks freed). 781 * 782 * If it must cut its scan of the object short due to an 783 * excessive number of swblocks, or is able to free the 784 * requested number of blocks, it will return n >= count 785 * and we break and pick it back up on a future attempt. 786 * 787 * Scan the object linearly and try to batch large sets of 788 * blocks that are likely to clean out entire swap radix 789 * tree leafs. 790 */ 791 lwkt_token_swap(); 792 lwkt_reltoken(&(*swindexp)->token); 793 794 n = swap_pager_condfree(object, &marker->dummy_obj.size, 795 (count + SWAP_META_MASK) & ~SWAP_META_MASK); 796 797 vm_object_drop(object); /* object may be invalid now */ 798 lwkt_gettoken(&(*swindexp)->token); 799 800 /* 801 * If we have exhausted the object or deleted our per-pass 802 * page limit then move us to the next object. Note that 803 * the current object may no longer be on the vm_object_entry. 804 */ 805 if (n <= 0 || 806 marker->save_off > vm_swapcache_cleanperobj) { 807 vm_swapcache_movemarker(marker, *swindexp, object); 808 didmove = 1; 809 } 810 811 /* 812 * If we have exhausted our max-launder stop for now. 813 */ 814 count -= n; 815 marker->save_off += n * PAGE_SIZE; 816 if (count < 0) 817 goto breakout; 818 } 819 820 /* 821 * Iterate vm_object_hash[] hash table 822 */ 823 TAILQ_REMOVE(&(*swindexp)->list, &marker->dummy_obj, object_entry); 824 lwkt_reltoken(&(*swindexp)->token); 825 if (++*swindexp >= &vm_object_hash[VMOBJ_HSIZE]) 826 *swindexp = &vm_object_hash[0]; 827 lwkt_gettoken(&(*swindexp)->token); 828 TAILQ_INSERT_HEAD(&(*swindexp)->list, &marker->dummy_obj, object_entry); 829 830 if (*swindexp != &vm_object_hash[0]) 831 goto outerloop; 832 833 breakout: 834 lwkt_reltoken(&(*swindexp)->token); 835 } 836 837 /* 838 * Move the marker past the current object. Object can be stale, but we 839 * still need it to determine if the marker has to be moved. If the object 840 * is still the 'current object' (object after the marker), we hop-scotch 841 * the marker past it. 842 */ 843 static void 844 vm_swapcache_movemarker(swmarker_t *marker, struct vm_object_hash *swindex, 845 vm_object_t object) 846 { 847 if (TAILQ_NEXT(&marker->dummy_obj, object_entry) == object) { 848 TAILQ_REMOVE(&swindex->list, &marker->dummy_obj, object_entry); 849 TAILQ_INSERT_AFTER(&swindex->list, object, 850 &marker->dummy_obj, object_entry); 851 } 852 } 853