1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 2010 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 "opt_vm.h" 55 #include <sys/param.h> 56 #include <sys/systm.h> 57 #include <sys/kernel.h> 58 #include <sys/proc.h> 59 #include <sys/kthread.h> 60 #include <sys/resourcevar.h> 61 #include <sys/signalvar.h> 62 #include <sys/vnode.h> 63 #include <sys/vmmeter.h> 64 #include <sys/sysctl.h> 65 #include <sys/eventhandler.h> 66 67 #include <vm/vm.h> 68 #include <vm/vm_param.h> 69 #include <sys/lock.h> 70 #include <vm/vm_object.h> 71 #include <vm/vm_page.h> 72 #include <vm/vm_map.h> 73 #include <vm/vm_pageout.h> 74 #include <vm/vm_pager.h> 75 #include <vm/swap_pager.h> 76 #include <vm/vm_extern.h> 77 78 #include <sys/thread2.h> 79 #include <sys/spinlock2.h> 80 #include <vm/vm_page2.h> 81 82 /* the kernel process "vm_pageout"*/ 83 static int vm_swapcached_flush (vm_page_t m, int isblkdev); 84 static int vm_swapcache_test(vm_page_t m); 85 static int vm_swapcache_writing_heuristic(void); 86 static int vm_swapcache_writing(vm_page_t marker, int count, int scount); 87 static void vm_swapcache_cleaning(vm_object_t marker, int *swindexp); 88 static void vm_swapcache_movemarker(vm_object_t marker, int swindex, 89 vm_object_t object); 90 struct thread *swapcached_thread; 91 92 SYSCTL_NODE(_vm, OID_AUTO, swapcache, CTLFLAG_RW, NULL, NULL); 93 94 int vm_swapcache_read_enable; 95 int vm_swapcache_inactive_heuristic; 96 static int vm_swapcache_sleep; 97 static int vm_swapcache_maxscan = PQ_L2_SIZE * 8; 98 static int vm_swapcache_maxlaunder = PQ_L2_SIZE * 4; 99 static int vm_swapcache_data_enable = 0; 100 static int vm_swapcache_meta_enable = 0; 101 static int vm_swapcache_maxswappct = 75; 102 static int vm_swapcache_hysteresis; 103 static int vm_swapcache_min_hysteresis; 104 int vm_swapcache_use_chflags = 1; /* require chflags cache */ 105 static int64_t vm_swapcache_minburst = 10000000LL; /* 10MB */ 106 static int64_t vm_swapcache_curburst = 4000000000LL; /* 4G after boot */ 107 static int64_t vm_swapcache_maxburst = 2000000000LL; /* 2G nominal max */ 108 static int64_t vm_swapcache_accrate = 100000LL; /* 100K/s */ 109 static int64_t vm_swapcache_write_count; 110 static int64_t vm_swapcache_maxfilesize; 111 static int64_t vm_swapcache_cleanperobj = 16*1024*1024; 112 113 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxlaunder, 114 CTLFLAG_RW, &vm_swapcache_maxlaunder, 0, ""); 115 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxscan, 116 CTLFLAG_RW, &vm_swapcache_maxscan, 0, ""); 117 118 SYSCTL_INT(_vm_swapcache, OID_AUTO, data_enable, 119 CTLFLAG_RW, &vm_swapcache_data_enable, 0, ""); 120 SYSCTL_INT(_vm_swapcache, OID_AUTO, meta_enable, 121 CTLFLAG_RW, &vm_swapcache_meta_enable, 0, ""); 122 SYSCTL_INT(_vm_swapcache, OID_AUTO, read_enable, 123 CTLFLAG_RW, &vm_swapcache_read_enable, 0, ""); 124 SYSCTL_INT(_vm_swapcache, OID_AUTO, maxswappct, 125 CTLFLAG_RW, &vm_swapcache_maxswappct, 0, ""); 126 SYSCTL_INT(_vm_swapcache, OID_AUTO, hysteresis, 127 CTLFLAG_RD, &vm_swapcache_hysteresis, 0, ""); 128 SYSCTL_INT(_vm_swapcache, OID_AUTO, min_hysteresis, 129 CTLFLAG_RW, &vm_swapcache_min_hysteresis, 0, ""); 130 SYSCTL_INT(_vm_swapcache, OID_AUTO, use_chflags, 131 CTLFLAG_RW, &vm_swapcache_use_chflags, 0, ""); 132 133 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, minburst, 134 CTLFLAG_RW, &vm_swapcache_minburst, 0, ""); 135 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, curburst, 136 CTLFLAG_RW, &vm_swapcache_curburst, 0, ""); 137 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, maxburst, 138 CTLFLAG_RW, &vm_swapcache_maxburst, 0, ""); 139 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, maxfilesize, 140 CTLFLAG_RW, &vm_swapcache_maxfilesize, 0, ""); 141 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, accrate, 142 CTLFLAG_RW, &vm_swapcache_accrate, 0, ""); 143 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, write_count, 144 CTLFLAG_RW, &vm_swapcache_write_count, 0, ""); 145 SYSCTL_QUAD(_vm_swapcache, OID_AUTO, cleanperobj, 146 CTLFLAG_RW, &vm_swapcache_cleanperobj, 0, ""); 147 148 #define SWAPMAX(adj) \ 149 ((int64_t)vm_swap_max * (vm_swapcache_maxswappct + (adj)) / 100) 150 151 /* 152 * When shutting down the machine we want to stop swapcache operation 153 * immediately so swap is not accessed after devices have been shuttered. 154 */ 155 static void 156 shutdown_swapcache(void *arg __unused) 157 { 158 vm_swapcache_read_enable = 0; 159 vm_swapcache_data_enable = 0; 160 vm_swapcache_meta_enable = 0; 161 wakeup(&vm_swapcache_sleep); /* shortcut 5-second wait */ 162 } 163 164 /* 165 * vm_swapcached is the high level pageout daemon. 166 * 167 * No requirements. 168 */ 169 static void 170 vm_swapcached_thread(void) 171 { 172 enum { SWAPC_WRITING, SWAPC_CLEANING } state = SWAPC_WRITING; 173 enum { SWAPB_BURSTING, SWAPB_RECOVERING } burst = SWAPB_BURSTING; 174 static struct vm_page page_marker[PQ_L2_SIZE]; 175 static struct vm_object swmarker; 176 static int swindex; 177 int q; 178 179 /* 180 * Thread setup 181 */ 182 curthread->td_flags |= TDF_SYSTHREAD; 183 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 184 swapcached_thread, SHUTDOWN_PRI_FIRST); 185 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_swapcache, 186 NULL, SHUTDOWN_PRI_SECOND); 187 188 /* 189 * Initialize our marker for the inactive scan (SWAPC_WRITING) 190 */ 191 bzero(&page_marker, sizeof(page_marker)); 192 for (q = 0; q < PQ_L2_SIZE; ++q) { 193 page_marker[q].flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 194 page_marker[q].queue = PQ_INACTIVE + q; 195 page_marker[q].pc = q; 196 page_marker[q].wire_count = 1; 197 vm_page_queues_spin_lock(PQ_INACTIVE + q); 198 TAILQ_INSERT_HEAD( 199 &vm_page_queues[PQ_INACTIVE + q].pl, 200 &page_marker[q], pageq); 201 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 202 } 203 204 vm_swapcache_min_hysteresis = 1024; 205 vm_swapcache_hysteresis = vm_swapcache_min_hysteresis; 206 vm_swapcache_inactive_heuristic = -vm_swapcache_hysteresis; 207 208 /* 209 * Initialize our marker for the vm_object scan (SWAPC_CLEANING) 210 */ 211 bzero(&swmarker, sizeof(swmarker)); 212 swmarker.type = OBJT_MARKER; 213 swindex = 0; 214 lwkt_gettoken(&vmobj_tokens[swindex]); 215 TAILQ_INSERT_HEAD(&vm_object_lists[swindex], 216 &swmarker, object_list); 217 lwkt_reltoken(&vmobj_tokens[swindex]); 218 219 for (;;) { 220 int reached_end; 221 int scount; 222 int count; 223 224 /* 225 * Handle shutdown 226 */ 227 kproc_suspend_loop(); 228 229 /* 230 * Check every 5 seconds when not enabled or if no swap 231 * is present. 232 */ 233 if ((vm_swapcache_data_enable == 0 && 234 vm_swapcache_meta_enable == 0 && 235 vm_swap_cache_use <= SWAPMAX(0)) || 236 vm_swap_max == 0) { 237 tsleep(&vm_swapcache_sleep, 0, "csleep", hz * 5); 238 continue; 239 } 240 241 /* 242 * Polling rate when enabled is approximately 10 hz. 243 */ 244 tsleep(&vm_swapcache_sleep, 0, "csleep", hz / 10); 245 246 /* 247 * State hysteresis. Generate write activity up to 75% of 248 * swap, then clean out swap assignments down to 70%, then 249 * repeat. 250 */ 251 if (state == SWAPC_WRITING) { 252 if (vm_swap_cache_use > SWAPMAX(0)) 253 state = SWAPC_CLEANING; 254 } else { 255 if (vm_swap_cache_use < SWAPMAX(-10)) 256 state = SWAPC_WRITING; 257 } 258 259 /* 260 * We are allowed to continue accumulating burst value 261 * in either state. Allow the user to set curburst > maxburst 262 * for the initial load-in. 263 */ 264 if (vm_swapcache_curburst < vm_swapcache_maxburst) { 265 vm_swapcache_curburst += vm_swapcache_accrate / 10; 266 if (vm_swapcache_curburst > vm_swapcache_maxburst) 267 vm_swapcache_curburst = vm_swapcache_maxburst; 268 } 269 270 /* 271 * We don't want to nickle-and-dime the scan as that will 272 * create unnecessary fragmentation. The minimum burst 273 * is one-seconds worth of accumulation. 274 */ 275 if (state != SWAPC_WRITING) { 276 vm_swapcache_cleaning(&swmarker, &swindex); 277 continue; 278 } 279 if (vm_swapcache_curburst < vm_swapcache_accrate) 280 continue; 281 282 reached_end = 0; 283 count = vm_swapcache_maxlaunder / PQ_L2_SIZE + 2; 284 scount = vm_swapcache_maxscan / PQ_L2_SIZE + 2; 285 286 if (burst == SWAPB_BURSTING) { 287 if (vm_swapcache_writing_heuristic()) { 288 for (q = 0; q < PQ_L2_SIZE; ++q) { 289 reached_end += 290 vm_swapcache_writing( 291 &page_marker[q], 292 count, 293 scount); 294 } 295 } 296 if (vm_swapcache_curburst <= 0) 297 burst = SWAPB_RECOVERING; 298 } else if (vm_swapcache_curburst > vm_swapcache_minburst) { 299 if (vm_swapcache_writing_heuristic()) { 300 for (q = 0; q < PQ_L2_SIZE; ++q) { 301 reached_end += 302 vm_swapcache_writing( 303 &page_marker[q], 304 count, 305 scount); 306 } 307 } 308 burst = SWAPB_BURSTING; 309 } 310 if (reached_end == PQ_L2_SIZE) { 311 vm_swapcache_inactive_heuristic = 312 -vm_swapcache_hysteresis; 313 } 314 } 315 316 /* 317 * Cleanup (NOT REACHED) 318 */ 319 for (q = 0; q < PQ_L2_SIZE; ++q) { 320 vm_page_queues_spin_lock(PQ_INACTIVE + q); 321 TAILQ_REMOVE( 322 &vm_page_queues[PQ_INACTIVE + q].pl, 323 &page_marker[q], pageq); 324 vm_page_queues_spin_unlock(PQ_INACTIVE + q); 325 } 326 327 lwkt_gettoken(&vmobj_tokens[swindex]); 328 TAILQ_REMOVE(&vm_object_lists[swindex], &swmarker, object_list); 329 lwkt_reltoken(&vmobj_tokens[swindex]); 330 } 331 332 static struct kproc_desc swpc_kp = { 333 "swapcached", 334 vm_swapcached_thread, 335 &swapcached_thread 336 }; 337 SYSINIT(swapcached, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start, &swpc_kp); 338 339 /* 340 * Deal with an overflow of the heuristic counter or if the user 341 * manually changes the hysteresis. 342 * 343 * Try to avoid small incremental pageouts by waiting for enough 344 * pages to buildup in the inactive queue to hopefully get a good 345 * burst in. This heuristic is bumped by the VM system and reset 346 * when our scan hits the end of the queue. 347 * 348 * Return TRUE if we need to take a writing pass. 349 */ 350 static int 351 vm_swapcache_writing_heuristic(void) 352 { 353 int hyst; 354 355 hyst = vmstats.v_inactive_count / 4; 356 if (hyst < vm_swapcache_min_hysteresis) 357 hyst = vm_swapcache_min_hysteresis; 358 cpu_ccfence(); 359 vm_swapcache_hysteresis = hyst; 360 361 if (vm_swapcache_inactive_heuristic < -hyst) 362 vm_swapcache_inactive_heuristic = -hyst; 363 364 return (vm_swapcache_inactive_heuristic >= 0); 365 } 366 367 /* 368 * Take a writing pass on one of the inactive queues, return non-zero if 369 * we hit the end of the queue. 370 */ 371 static int 372 vm_swapcache_writing(vm_page_t marker, int count, int scount) 373 { 374 vm_object_t object; 375 struct vnode *vp; 376 vm_page_t m; 377 int isblkdev; 378 379 /* 380 * Scan the inactive queue from our marker to locate 381 * suitable pages to push to the swap cache. 382 * 383 * We are looking for clean vnode-backed pages. 384 */ 385 vm_page_queues_spin_lock(marker->queue); 386 while ((m = TAILQ_NEXT(marker, pageq)) != NULL && 387 count > 0 && scount-- > 0) { 388 KKASSERT(m->queue == marker->queue); 389 390 if (vm_swapcache_curburst < 0) 391 break; 392 TAILQ_REMOVE( 393 &vm_page_queues[marker->queue].pl, marker, pageq); 394 TAILQ_INSERT_AFTER( 395 &vm_page_queues[marker->queue].pl, m, marker, pageq); 396 397 /* 398 * Ignore markers and ignore pages that already have a swap 399 * assignment. 400 */ 401 if (m->flags & (PG_MARKER | PG_SWAPPED)) 402 continue; 403 if (vm_page_busy_try(m, TRUE)) 404 continue; 405 vm_page_queues_spin_unlock(marker->queue); 406 407 if ((object = m->object) == NULL) { 408 vm_page_wakeup(m); 409 vm_page_queues_spin_lock(marker->queue); 410 continue; 411 } 412 vm_object_hold(object); 413 if (m->object != object) { 414 vm_object_drop(object); 415 vm_page_wakeup(m); 416 vm_page_queues_spin_lock(marker->queue); 417 continue; 418 } 419 if (vm_swapcache_test(m)) { 420 vm_object_drop(object); 421 vm_page_wakeup(m); 422 vm_page_queues_spin_lock(marker->queue); 423 continue; 424 } 425 426 vp = object->handle; 427 if (vp == NULL) { 428 vm_object_drop(object); 429 vm_page_wakeup(m); 430 vm_page_queues_spin_lock(marker->queue); 431 continue; 432 } 433 434 switch(vp->v_type) { 435 case VREG: 436 /* 437 * PG_NOTMETA generically means 'don't swapcache this', 438 * and HAMMER will set this for regular data buffers 439 * (and leave it unset for meta-data buffers) as 440 * appropriate when double buffering is enabled. 441 */ 442 if (m->flags & PG_NOTMETA) { 443 vm_object_drop(object); 444 vm_page_wakeup(m); 445 vm_page_queues_spin_lock(marker->queue); 446 continue; 447 } 448 449 /* 450 * If data_enable is 0 do not try to swapcache data. 451 * If use_chflags is set then only swapcache data for 452 * VSWAPCACHE marked vnodes, otherwise any vnode. 453 */ 454 if (vm_swapcache_data_enable == 0 || 455 ((vp->v_flag & VSWAPCACHE) == 0 && 456 vm_swapcache_use_chflags)) { 457 vm_object_drop(object); 458 vm_page_wakeup(m); 459 vm_page_queues_spin_lock(marker->queue); 460 continue; 461 } 462 if (vm_swapcache_maxfilesize && 463 object->size > 464 (vm_swapcache_maxfilesize >> PAGE_SHIFT)) { 465 vm_object_drop(object); 466 vm_page_wakeup(m); 467 vm_page_queues_spin_lock(marker->queue); 468 continue; 469 } 470 isblkdev = 0; 471 break; 472 case VCHR: 473 /* 474 * PG_NOTMETA generically means 'don't swapcache this', 475 * and HAMMER will set this for regular data buffers 476 * (and leave it unset for meta-data buffers) as 477 * appropriate when double buffering is enabled. 478 */ 479 if (m->flags & PG_NOTMETA) { 480 vm_object_drop(object); 481 vm_page_wakeup(m); 482 vm_page_queues_spin_lock(marker->queue); 483 continue; 484 } 485 if (vm_swapcache_meta_enable == 0) { 486 vm_object_drop(object); 487 vm_page_wakeup(m); 488 vm_page_queues_spin_lock(marker->queue); 489 continue; 490 } 491 isblkdev = 1; 492 break; 493 default: 494 vm_object_drop(object); 495 vm_page_wakeup(m); 496 vm_page_queues_spin_lock(marker->queue); 497 continue; 498 } 499 500 501 /* 502 * Assign swap and initiate I/O. 503 * 504 * (adjust for the --count which also occurs in the loop) 505 */ 506 count -= vm_swapcached_flush(m, isblkdev); 507 508 /* 509 * Setup for next loop using marker. 510 */ 511 vm_object_drop(object); 512 vm_page_queues_spin_lock(marker->queue); 513 } 514 515 /* 516 * The marker could wind up at the end, which is ok. If we hit the 517 * end of the list adjust the heuristic. 518 * 519 * Earlier inactive pages that were dirty and become clean 520 * are typically moved to the end of PQ_INACTIVE by virtue 521 * of vfs_vmio_release() when they become unwired from the 522 * buffer cache. 523 */ 524 vm_page_queues_spin_unlock(marker->queue); 525 526 /* 527 * m invalid but can be used to test for NULL 528 */ 529 return (m == NULL); 530 } 531 532 /* 533 * Flush the specified page using the swap_pager. The page 534 * must be busied by the caller and its disposition will become 535 * the responsibility of this function. 536 * 537 * Try to collect surrounding pages, including pages which may 538 * have already been assigned swap. Try to cluster within a 539 * contiguous aligned SMAP_META_PAGES (typ 16 x PAGE_SIZE) block 540 * to match what swap_pager_putpages() can do. 541 * 542 * We also want to try to match against the buffer cache blocksize 543 * but we don't really know what it is here. Since the buffer cache 544 * wires and unwires pages in groups the fact that we skip wired pages 545 * should be sufficient. 546 * 547 * Returns a count of pages we might have flushed (minimum 1) 548 */ 549 static 550 int 551 vm_swapcached_flush(vm_page_t m, int isblkdev) 552 { 553 vm_object_t object; 554 vm_page_t marray[SWAP_META_PAGES]; 555 vm_pindex_t basei; 556 int rtvals[SWAP_META_PAGES]; 557 int x; 558 int i; 559 int j; 560 int count; 561 int error; 562 563 vm_page_io_start(m); 564 vm_page_protect(m, VM_PROT_READ); 565 object = m->object; 566 vm_object_hold(object); 567 568 /* 569 * Try to cluster around (m), keeping in mind that the swap pager 570 * can only do SMAP_META_PAGES worth of continguous write. 571 */ 572 x = (int)m->pindex & SWAP_META_MASK; 573 marray[x] = m; 574 basei = m->pindex; 575 vm_page_wakeup(m); 576 577 for (i = x - 1; i >= 0; --i) { 578 m = vm_page_lookup_busy_try(object, basei - x + i, 579 TRUE, &error); 580 if (error || m == NULL) 581 break; 582 if (vm_swapcache_test(m)) { 583 vm_page_wakeup(m); 584 break; 585 } 586 if (isblkdev && (m->flags & PG_NOTMETA)) { 587 vm_page_wakeup(m); 588 break; 589 } 590 vm_page_io_start(m); 591 vm_page_protect(m, VM_PROT_READ); 592 if (m->queue - m->pc == PQ_CACHE) { 593 vm_page_unqueue_nowakeup(m); 594 vm_page_deactivate(m); 595 } 596 marray[i] = m; 597 vm_page_wakeup(m); 598 } 599 ++i; 600 601 for (j = x + 1; j < SWAP_META_PAGES; ++j) { 602 m = vm_page_lookup_busy_try(object, basei - x + j, 603 TRUE, &error); 604 if (error || m == NULL) 605 break; 606 if (vm_swapcache_test(m)) { 607 vm_page_wakeup(m); 608 break; 609 } 610 if (isblkdev && (m->flags & PG_NOTMETA)) { 611 vm_page_wakeup(m); 612 break; 613 } 614 vm_page_io_start(m); 615 vm_page_protect(m, VM_PROT_READ); 616 if (m->queue - m->pc == PQ_CACHE) { 617 vm_page_unqueue_nowakeup(m); 618 vm_page_deactivate(m); 619 } 620 marray[j] = m; 621 vm_page_wakeup(m); 622 } 623 624 count = j - i; 625 vm_object_pip_add(object, count); 626 swap_pager_putpages(object, marray + i, count, FALSE, rtvals + i); 627 vm_swapcache_write_count += count * PAGE_SIZE; 628 vm_swapcache_curburst -= count * PAGE_SIZE; 629 630 while (i < j) { 631 if (rtvals[i] != VM_PAGER_PEND) { 632 vm_page_busy_wait(marray[i], FALSE, "swppgfd"); 633 vm_page_io_finish(marray[i]); 634 vm_page_wakeup(marray[i]); 635 vm_object_pip_wakeup(object); 636 } 637 ++i; 638 } 639 vm_object_drop(object); 640 return(count); 641 } 642 643 /* 644 * Test whether a VM page is suitable for writing to the swapcache. 645 * Does not test m->queue, PG_MARKER, or PG_SWAPPED. 646 * 647 * Returns 0 on success, 1 on failure 648 */ 649 static int 650 vm_swapcache_test(vm_page_t m) 651 { 652 vm_object_t object; 653 654 if (m->flags & PG_UNMANAGED) 655 return(1); 656 if (m->hold_count || m->wire_count) 657 return(1); 658 if (m->valid != VM_PAGE_BITS_ALL) 659 return(1); 660 if (m->dirty & m->valid) 661 return(1); 662 if ((object = m->object) == NULL) 663 return(1); 664 if (object->type != OBJT_VNODE || 665 (object->flags & OBJ_DEAD)) { 666 return(1); 667 } 668 vm_page_test_dirty(m); 669 if (m->dirty & m->valid) 670 return(1); 671 return(0); 672 } 673 674 /* 675 * Cleaning pass. 676 * 677 * We clean whole objects up to 16MB 678 */ 679 static 680 void 681 vm_swapcache_cleaning(vm_object_t marker, int *swindexp) 682 { 683 vm_object_t object; 684 struct vnode *vp; 685 int count; 686 int scount; 687 int n; 688 689 count = vm_swapcache_maxlaunder; 690 scount = vm_swapcache_maxscan; 691 692 /* 693 * Look for vnode objects 694 */ 695 lwkt_gettoken(&vmobj_tokens[*swindexp]); 696 697 outerloop: 698 while ((object = TAILQ_NEXT(marker, object_list)) != NULL) { 699 /* 700 * We have to skip markers. We cannot hold/drop marker 701 * objects! 702 */ 703 if (object->type == OBJT_MARKER) { 704 vm_swapcache_movemarker(marker, *swindexp, object); 705 continue; 706 } 707 708 /* 709 * Safety, or in case there are millions of VM objects 710 * without swapcache backing. 711 */ 712 if (--scount <= 0) 713 goto breakout; 714 715 /* 716 * We must hold the object before potentially yielding. 717 */ 718 vm_object_hold(object); 719 lwkt_yield(); 720 721 /* 722 * Only operate on live VNODE objects that are either 723 * VREG or VCHR (VCHR for meta-data). 724 */ 725 if ((object->type != OBJT_VNODE) || 726 ((object->flags & OBJ_DEAD) || 727 object->swblock_count == 0) || 728 ((vp = object->handle) == NULL) || 729 (vp->v_type != VREG && vp->v_type != VCHR)) { 730 vm_object_drop(object); 731 /* object may be invalid now */ 732 vm_swapcache_movemarker(marker, *swindexp, object); 733 continue; 734 } 735 736 /* 737 * Reset the object pindex stored in the marker if the 738 * working object has changed. 739 */ 740 if (marker->backing_object != object) { 741 marker->size = 0; 742 marker->backing_object_offset = 0; 743 marker->backing_object = object; 744 } 745 746 /* 747 * Look for swblocks starting at our iterator. 748 * 749 * The swap_pager_condfree() function attempts to free 750 * swap space starting at the specified index. The index 751 * will be updated on return. The function will return 752 * a scan factor (NOT the number of blocks freed). 753 * 754 * If it must cut its scan of the object short due to an 755 * excessive number of swblocks, or is able to free the 756 * requested number of blocks, it will return n >= count 757 * and we break and pick it back up on a future attempt. 758 * 759 * Scan the object linearly and try to batch large sets of 760 * blocks that are likely to clean out entire swap radix 761 * tree leafs. 762 */ 763 lwkt_token_swap(); 764 lwkt_reltoken(&vmobj_tokens[*swindexp]); 765 766 n = swap_pager_condfree(object, &marker->size, 767 (count + SWAP_META_MASK) & ~SWAP_META_MASK); 768 769 vm_object_drop(object); /* object may be invalid now */ 770 lwkt_gettoken(&vmobj_tokens[*swindexp]); 771 772 /* 773 * If we have exhausted the object or deleted our per-pass 774 * page limit then move us to the next object. Note that 775 * the current object may no longer be on the vm_object_list. 776 */ 777 if (n <= 0 || 778 marker->backing_object_offset > vm_swapcache_cleanperobj) { 779 vm_swapcache_movemarker(marker, *swindexp, object); 780 } 781 782 /* 783 * If we have exhausted our max-launder stop for now. 784 */ 785 count -= n; 786 marker->backing_object_offset += n * PAGE_SIZE; 787 if (count < 0) 788 goto breakout; 789 } 790 791 /* 792 * Iterate vm_object_lists[] hash table 793 */ 794 TAILQ_REMOVE(&vm_object_lists[*swindexp], marker, object_list); 795 lwkt_reltoken(&vmobj_tokens[*swindexp]); 796 if (++*swindexp >= VMOBJ_HSIZE) 797 *swindexp = 0; 798 lwkt_gettoken(&vmobj_tokens[*swindexp]); 799 TAILQ_INSERT_HEAD(&vm_object_lists[*swindexp], marker, object_list); 800 801 if (*swindexp != 0) 802 goto outerloop; 803 804 breakout: 805 lwkt_reltoken(&vmobj_tokens[*swindexp]); 806 } 807 808 /* 809 * Move the marker past the current object. Object can be stale, but we 810 * still need it to determine if the marker has to be moved. If the object 811 * is still the 'current object' (object after the marker), we hop-scotch 812 * the marker past it. 813 */ 814 static void 815 vm_swapcache_movemarker(vm_object_t marker, int swindex, vm_object_t object) 816 { 817 if (TAILQ_NEXT(marker, object_list) == object) { 818 TAILQ_REMOVE(&vm_object_lists[swindex], marker, object_list); 819 TAILQ_INSERT_AFTER(&vm_object_lists[swindex], object, 820 marker, object_list); 821 } 822 } 823