| 1 | /* $NetBSD: uvm_pdaemon.c,v 1.108 2013/10/25 20:28:33 martin 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. Neither the name of the University nor the names of its contributors |
| 21 | * may be used to endorse or promote products derived from this software |
| 22 | * without specific prior written permission. |
| 23 | * |
| 24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 34 | * SUCH DAMAGE. |
| 35 | * |
| 36 | * @(#)vm_pageout.c 8.5 (Berkeley) 2/14/94 |
| 37 | * from: Id: uvm_pdaemon.c,v 1.1.2.32 1998/02/06 05:26:30 chs Exp |
| 38 | * |
| 39 | * |
| 40 | * Copyright (c) 1987, 1990 Carnegie-Mellon University. |
| 41 | * All rights reserved. |
| 42 | * |
| 43 | * Permission to use, copy, modify and distribute this software and |
| 44 | * its documentation is hereby granted, provided that both the copyright |
| 45 | * notice and this permission notice appear in all copies of the |
| 46 | * software, derivative works or modified versions, and any portions |
| 47 | * thereof, and that both notices appear in supporting documentation. |
| 48 | * |
| 49 | * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" |
| 50 | * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND |
| 51 | * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. |
| 52 | * |
| 53 | * Carnegie Mellon requests users of this software to return to |
| 54 | * |
| 55 | * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU |
| 56 | * School of Computer Science |
| 57 | * Carnegie Mellon University |
| 58 | * Pittsburgh PA 15213-3890 |
| 59 | * |
| 60 | * any improvements or extensions that they make and grant Carnegie the |
| 61 | * rights to redistribute these changes. |
| 62 | */ |
| 63 | |
| 64 | /* |
| 65 | * uvm_pdaemon.c: the page daemon |
| 66 | */ |
| 67 | |
| 68 | #include <sys/cdefs.h> |
| 69 | __KERNEL_RCSID(0, "$NetBSD: uvm_pdaemon.c,v 1.108 2013/10/25 20:28:33 martin Exp $" ); |
| 70 | |
| 71 | #include "opt_uvmhist.h" |
| 72 | #include "opt_readahead.h" |
| 73 | |
| 74 | #include <sys/param.h> |
| 75 | #include <sys/proc.h> |
| 76 | #include <sys/systm.h> |
| 77 | #include <sys/kernel.h> |
| 78 | #include <sys/pool.h> |
| 79 | #include <sys/buf.h> |
| 80 | #include <sys/module.h> |
| 81 | #include <sys/atomic.h> |
| 82 | |
| 83 | #include <uvm/uvm.h> |
| 84 | #include <uvm/uvm_pdpolicy.h> |
| 85 | |
| 86 | #ifdef UVMHIST |
| 87 | UVMHIST_DEFINE(pdhist); |
| 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 | #define UVMPD_NUMTRYLOCKOWNER 16 |
| 100 | |
| 101 | /* |
| 102 | * local prototypes |
| 103 | */ |
| 104 | |
| 105 | static void uvmpd_scan(void); |
| 106 | static void uvmpd_scan_queue(void); |
| 107 | static void uvmpd_tune(void); |
| 108 | |
| 109 | static unsigned int uvm_pagedaemon_waiters; |
| 110 | |
| 111 | /* |
| 112 | * XXX hack to avoid hangs when large processes fork. |
| 113 | */ |
| 114 | u_int ; |
| 115 | |
| 116 | /* |
| 117 | * uvm_wait: wait (sleep) for the page daemon to free some pages |
| 118 | * |
| 119 | * => should be called with all locks released |
| 120 | * => should _not_ be called by the page daemon (to avoid deadlock) |
| 121 | */ |
| 122 | |
| 123 | void |
| 124 | uvm_wait(const char *wmsg) |
| 125 | { |
| 126 | int timo = 0; |
| 127 | |
| 128 | mutex_spin_enter(&uvm_fpageqlock); |
| 129 | |
| 130 | /* |
| 131 | * check for page daemon going to sleep (waiting for itself) |
| 132 | */ |
| 133 | |
| 134 | if (curlwp == uvm.pagedaemon_lwp && uvmexp.paging == 0) { |
| 135 | /* |
| 136 | * now we have a problem: the pagedaemon wants to go to |
| 137 | * sleep until it frees more memory. but how can it |
| 138 | * free more memory if it is asleep? that is a deadlock. |
| 139 | * we have two options: |
| 140 | * [1] panic now |
| 141 | * [2] put a timeout on the sleep, thus causing the |
| 142 | * pagedaemon to only pause (rather than sleep forever) |
| 143 | * |
| 144 | * note that option [2] will only help us if we get lucky |
| 145 | * and some other process on the system breaks the deadlock |
| 146 | * by exiting or freeing memory (thus allowing the pagedaemon |
| 147 | * to continue). for now we panic if DEBUG is defined, |
| 148 | * otherwise we hope for the best with option [2] (better |
| 149 | * yet, this should never happen in the first place!). |
| 150 | */ |
| 151 | |
| 152 | printf("pagedaemon: deadlock detected!\n" ); |
| 153 | timo = hz >> 3; /* set timeout */ |
| 154 | #if defined(DEBUG) |
| 155 | /* DEBUG: panic so we can debug it */ |
| 156 | panic("pagedaemon deadlock" ); |
| 157 | #endif |
| 158 | } |
| 159 | |
| 160 | uvm_pagedaemon_waiters++; |
| 161 | wakeup(&uvm.pagedaemon); /* wake the daemon! */ |
| 162 | UVM_UNLOCK_AND_WAIT(&uvmexp.free, &uvm_fpageqlock, false, wmsg, timo); |
| 163 | } |
| 164 | |
| 165 | /* |
| 166 | * uvm_kick_pdaemon: perform checks to determine if we need to |
| 167 | * give the pagedaemon a nudge, and do so if necessary. |
| 168 | * |
| 169 | * => called with uvm_fpageqlock held. |
| 170 | */ |
| 171 | |
| 172 | void |
| 173 | uvm_kick_pdaemon(void) |
| 174 | { |
| 175 | |
| 176 | KASSERT(mutex_owned(&uvm_fpageqlock)); |
| 177 | |
| 178 | if (uvmexp.free + uvmexp.paging < uvmexp.freemin || |
| 179 | (uvmexp.free + uvmexp.paging < uvmexp.freetarg && |
| 180 | uvmpdpol_needsscan_p()) || |
| 181 | uvm_km_va_starved_p()) { |
| 182 | wakeup(&uvm.pagedaemon); |
| 183 | } |
| 184 | } |
| 185 | |
| 186 | /* |
| 187 | * uvmpd_tune: tune paging parameters |
| 188 | * |
| 189 | * => called when ever memory is added (or removed?) to the system |
| 190 | * => caller must call with page queues locked |
| 191 | */ |
| 192 | |
| 193 | static void |
| 194 | uvmpd_tune(void) |
| 195 | { |
| 196 | int val; |
| 197 | |
| 198 | UVMHIST_FUNC("uvmpd_tune" ); UVMHIST_CALLED(pdhist); |
| 199 | |
| 200 | /* |
| 201 | * try to keep 0.5% of available RAM free, but limit to between |
| 202 | * 128k and 1024k per-CPU. XXX: what are these values good for? |
| 203 | */ |
| 204 | val = uvmexp.npages / 200; |
| 205 | val = MAX(val, (128*1024) >> PAGE_SHIFT); |
| 206 | val = MIN(val, (1024*1024) >> PAGE_SHIFT); |
| 207 | val *= ncpu; |
| 208 | |
| 209 | /* Make sure there's always a user page free. */ |
| 210 | if (val < uvmexp.reserve_kernel + 1) |
| 211 | val = uvmexp.reserve_kernel + 1; |
| 212 | uvmexp.freemin = val; |
| 213 | |
| 214 | /* Calculate free target. */ |
| 215 | val = (uvmexp.freemin * 4) / 3; |
| 216 | if (val <= uvmexp.freemin) |
| 217 | val = uvmexp.freemin + 1; |
| 218 | uvmexp.freetarg = val + atomic_swap_uint(&uvm_extrapages, 0); |
| 219 | |
| 220 | uvmexp.wiredmax = uvmexp.npages / 3; |
| 221 | UVMHIST_LOG(pdhist, "<- done, freemin=%d, freetarg=%d, wiredmax=%d" , |
| 222 | uvmexp.freemin, uvmexp.freetarg, uvmexp.wiredmax, 0); |
| 223 | } |
| 224 | |
| 225 | /* |
| 226 | * uvm_pageout: the main loop for the pagedaemon |
| 227 | */ |
| 228 | |
| 229 | void |
| 230 | uvm_pageout(void *arg) |
| 231 | { |
| 232 | int bufcnt, npages = 0; |
| 233 | int = 0; |
| 234 | struct pool *pp; |
| 235 | |
| 236 | UVMHIST_FUNC("uvm_pageout" ); UVMHIST_CALLED(pdhist); |
| 237 | |
| 238 | UVMHIST_LOG(pdhist,"<starting uvm pagedaemon>" , 0, 0, 0, 0); |
| 239 | |
| 240 | /* |
| 241 | * ensure correct priority and set paging parameters... |
| 242 | */ |
| 243 | |
| 244 | uvm.pagedaemon_lwp = curlwp; |
| 245 | mutex_enter(&uvm_pageqlock); |
| 246 | npages = uvmexp.npages; |
| 247 | uvmpd_tune(); |
| 248 | mutex_exit(&uvm_pageqlock); |
| 249 | |
| 250 | /* |
| 251 | * main loop |
| 252 | */ |
| 253 | |
| 254 | for (;;) { |
| 255 | bool needsscan, needsfree, kmem_va_starved; |
| 256 | |
| 257 | kmem_va_starved = uvm_km_va_starved_p(); |
| 258 | |
| 259 | mutex_spin_enter(&uvm_fpageqlock); |
| 260 | if ((uvm_pagedaemon_waiters == 0 || uvmexp.paging > 0) && |
| 261 | !kmem_va_starved) { |
| 262 | UVMHIST_LOG(pdhist," <<SLEEPING>>" ,0,0,0,0); |
| 263 | UVM_UNLOCK_AND_WAIT(&uvm.pagedaemon, |
| 264 | &uvm_fpageqlock, false, "pgdaemon" , 0); |
| 265 | uvmexp.pdwoke++; |
| 266 | UVMHIST_LOG(pdhist," <<WOKE UP>>" ,0,0,0,0); |
| 267 | } else { |
| 268 | mutex_spin_exit(&uvm_fpageqlock); |
| 269 | } |
| 270 | |
| 271 | /* |
| 272 | * now lock page queues and recompute inactive count |
| 273 | */ |
| 274 | |
| 275 | mutex_enter(&uvm_pageqlock); |
| 276 | if (npages != uvmexp.npages || extrapages != uvm_extrapages) { |
| 277 | npages = uvmexp.npages; |
| 278 | extrapages = uvm_extrapages; |
| 279 | mutex_spin_enter(&uvm_fpageqlock); |
| 280 | uvmpd_tune(); |
| 281 | mutex_spin_exit(&uvm_fpageqlock); |
| 282 | } |
| 283 | |
| 284 | uvmpdpol_tune(); |
| 285 | |
| 286 | /* |
| 287 | * Estimate a hint. Note that bufmem are returned to |
| 288 | * system only when entire pool page is empty. |
| 289 | */ |
| 290 | mutex_spin_enter(&uvm_fpageqlock); |
| 291 | bufcnt = uvmexp.freetarg - uvmexp.free; |
| 292 | if (bufcnt < 0) |
| 293 | bufcnt = 0; |
| 294 | |
| 295 | UVMHIST_LOG(pdhist," free/ftarg=%d/%d" , |
| 296 | uvmexp.free, uvmexp.freetarg, 0,0); |
| 297 | |
| 298 | needsfree = uvmexp.free + uvmexp.paging < uvmexp.freetarg; |
| 299 | needsscan = needsfree || uvmpdpol_needsscan_p(); |
| 300 | |
| 301 | /* |
| 302 | * scan if needed |
| 303 | */ |
| 304 | if (needsscan) { |
| 305 | mutex_spin_exit(&uvm_fpageqlock); |
| 306 | uvmpd_scan(); |
| 307 | mutex_spin_enter(&uvm_fpageqlock); |
| 308 | } |
| 309 | |
| 310 | /* |
| 311 | * if there's any free memory to be had, |
| 312 | * wake up any waiters. |
| 313 | */ |
| 314 | if (uvmexp.free > uvmexp.reserve_kernel || |
| 315 | uvmexp.paging == 0) { |
| 316 | wakeup(&uvmexp.free); |
| 317 | uvm_pagedaemon_waiters = 0; |
| 318 | } |
| 319 | mutex_spin_exit(&uvm_fpageqlock); |
| 320 | |
| 321 | /* |
| 322 | * scan done. unlock page queues (the only lock we are holding) |
| 323 | */ |
| 324 | mutex_exit(&uvm_pageqlock); |
| 325 | |
| 326 | /* |
| 327 | * if we don't need free memory, we're done. |
| 328 | */ |
| 329 | |
| 330 | if (!needsfree && !kmem_va_starved) |
| 331 | continue; |
| 332 | |
| 333 | /* |
| 334 | * kill unused metadata buffers. |
| 335 | */ |
| 336 | mutex_enter(&bufcache_lock); |
| 337 | buf_drain(bufcnt << PAGE_SHIFT); |
| 338 | mutex_exit(&bufcache_lock); |
| 339 | |
| 340 | /* |
| 341 | * drain the pools. |
| 342 | */ |
| 343 | pool_drain(&pp); |
| 344 | } |
| 345 | /*NOTREACHED*/ |
| 346 | } |
| 347 | |
| 348 | |
| 349 | /* |
| 350 | * uvm_aiodone_worker: a workqueue callback for the aiodone daemon. |
| 351 | */ |
| 352 | |
| 353 | void |
| 354 | uvm_aiodone_worker(struct work *wk, void *dummy) |
| 355 | { |
| 356 | struct buf *bp = (void *)wk; |
| 357 | |
| 358 | KASSERT(&bp->b_work == wk); |
| 359 | |
| 360 | /* |
| 361 | * process an i/o that's done. |
| 362 | */ |
| 363 | |
| 364 | (*bp->b_iodone)(bp); |
| 365 | } |
| 366 | |
| 367 | void |
| 368 | uvm_pageout_start(int npages) |
| 369 | { |
| 370 | |
| 371 | mutex_spin_enter(&uvm_fpageqlock); |
| 372 | uvmexp.paging += npages; |
| 373 | mutex_spin_exit(&uvm_fpageqlock); |
| 374 | } |
| 375 | |
| 376 | void |
| 377 | uvm_pageout_done(int npages) |
| 378 | { |
| 379 | |
| 380 | mutex_spin_enter(&uvm_fpageqlock); |
| 381 | KASSERT(uvmexp.paging >= npages); |
| 382 | uvmexp.paging -= npages; |
| 383 | |
| 384 | /* |
| 385 | * wake up either of pagedaemon or LWPs waiting for it. |
| 386 | */ |
| 387 | |
| 388 | if (uvmexp.free <= uvmexp.reserve_kernel) { |
| 389 | wakeup(&uvm.pagedaemon); |
| 390 | } else { |
| 391 | wakeup(&uvmexp.free); |
| 392 | uvm_pagedaemon_waiters = 0; |
| 393 | } |
| 394 | mutex_spin_exit(&uvm_fpageqlock); |
| 395 | } |
| 396 | |
| 397 | /* |
| 398 | * uvmpd_trylockowner: trylock the page's owner. |
| 399 | * |
| 400 | * => called with pageq locked. |
| 401 | * => resolve orphaned O->A loaned page. |
| 402 | * => return the locked mutex on success. otherwise, return NULL. |
| 403 | */ |
| 404 | |
| 405 | kmutex_t * |
| 406 | uvmpd_trylockowner(struct vm_page *pg) |
| 407 | { |
| 408 | struct uvm_object *uobj = pg->uobject; |
| 409 | kmutex_t *slock; |
| 410 | |
| 411 | KASSERT(mutex_owned(&uvm_pageqlock)); |
| 412 | |
| 413 | if (uobj != NULL) { |
| 414 | slock = uobj->vmobjlock; |
| 415 | } else { |
| 416 | struct vm_anon *anon = pg->uanon; |
| 417 | |
| 418 | KASSERT(anon != NULL); |
| 419 | slock = anon->an_lock; |
| 420 | } |
| 421 | |
| 422 | if (!mutex_tryenter(slock)) { |
| 423 | return NULL; |
| 424 | } |
| 425 | |
| 426 | if (uobj == NULL) { |
| 427 | |
| 428 | /* |
| 429 | * set PQ_ANON if it isn't set already. |
| 430 | */ |
| 431 | |
| 432 | if ((pg->pqflags & PQ_ANON) == 0) { |
| 433 | KASSERT(pg->loan_count > 0); |
| 434 | pg->loan_count--; |
| 435 | pg->pqflags |= PQ_ANON; |
| 436 | /* anon now owns it */ |
| 437 | } |
| 438 | } |
| 439 | |
| 440 | return slock; |
| 441 | } |
| 442 | |
| 443 | #if defined(VMSWAP) |
| 444 | struct swapcluster { |
| 445 | int swc_slot; |
| 446 | int swc_nallocated; |
| 447 | int swc_nused; |
| 448 | struct vm_page *swc_pages[howmany(MAXPHYS, MIN_PAGE_SIZE)]; |
| 449 | }; |
| 450 | |
| 451 | static void |
| 452 | swapcluster_init(struct swapcluster *swc) |
| 453 | { |
| 454 | |
| 455 | swc->swc_slot = 0; |
| 456 | swc->swc_nused = 0; |
| 457 | } |
| 458 | |
| 459 | static int |
| 460 | swapcluster_allocslots(struct swapcluster *swc) |
| 461 | { |
| 462 | int slot; |
| 463 | int npages; |
| 464 | |
| 465 | if (swc->swc_slot != 0) { |
| 466 | return 0; |
| 467 | } |
| 468 | |
| 469 | /* Even with strange MAXPHYS, the shift |
| 470 | implicitly rounds down to a page. */ |
| 471 | npages = MAXPHYS >> PAGE_SHIFT; |
| 472 | slot = uvm_swap_alloc(&npages, true); |
| 473 | if (slot == 0) { |
| 474 | return ENOMEM; |
| 475 | } |
| 476 | swc->swc_slot = slot; |
| 477 | swc->swc_nallocated = npages; |
| 478 | swc->swc_nused = 0; |
| 479 | |
| 480 | return 0; |
| 481 | } |
| 482 | |
| 483 | static int |
| 484 | swapcluster_add(struct swapcluster *swc, struct vm_page *pg) |
| 485 | { |
| 486 | int slot; |
| 487 | struct uvm_object *uobj; |
| 488 | |
| 489 | KASSERT(swc->swc_slot != 0); |
| 490 | KASSERT(swc->swc_nused < swc->swc_nallocated); |
| 491 | KASSERT((pg->pqflags & PQ_SWAPBACKED) != 0); |
| 492 | |
| 493 | slot = swc->swc_slot + swc->swc_nused; |
| 494 | uobj = pg->uobject; |
| 495 | if (uobj == NULL) { |
| 496 | KASSERT(mutex_owned(pg->uanon->an_lock)); |
| 497 | pg->uanon->an_swslot = slot; |
| 498 | } else { |
| 499 | int result; |
| 500 | |
| 501 | KASSERT(mutex_owned(uobj->vmobjlock)); |
| 502 | result = uao_set_swslot(uobj, pg->offset >> PAGE_SHIFT, slot); |
| 503 | if (result == -1) { |
| 504 | return ENOMEM; |
| 505 | } |
| 506 | } |
| 507 | swc->swc_pages[swc->swc_nused] = pg; |
| 508 | swc->swc_nused++; |
| 509 | |
| 510 | return 0; |
| 511 | } |
| 512 | |
| 513 | static void |
| 514 | swapcluster_flush(struct swapcluster *swc, bool now) |
| 515 | { |
| 516 | int slot; |
| 517 | int nused; |
| 518 | int nallocated; |
| 519 | int error __diagused; |
| 520 | |
| 521 | if (swc->swc_slot == 0) { |
| 522 | return; |
| 523 | } |
| 524 | KASSERT(swc->swc_nused <= swc->swc_nallocated); |
| 525 | |
| 526 | slot = swc->swc_slot; |
| 527 | nused = swc->swc_nused; |
| 528 | nallocated = swc->swc_nallocated; |
| 529 | |
| 530 | /* |
| 531 | * if this is the final pageout we could have a few |
| 532 | * unused swap blocks. if so, free them now. |
| 533 | */ |
| 534 | |
| 535 | if (nused < nallocated) { |
| 536 | if (!now) { |
| 537 | return; |
| 538 | } |
| 539 | uvm_swap_free(slot + nused, nallocated - nused); |
| 540 | } |
| 541 | |
| 542 | /* |
| 543 | * now start the pageout. |
| 544 | */ |
| 545 | |
| 546 | if (nused > 0) { |
| 547 | uvmexp.pdpageouts++; |
| 548 | uvm_pageout_start(nused); |
| 549 | error = uvm_swap_put(slot, swc->swc_pages, nused, 0); |
| 550 | KASSERT(error == 0 || error == ENOMEM); |
| 551 | } |
| 552 | |
| 553 | /* |
| 554 | * zero swslot to indicate that we are |
| 555 | * no longer building a swap-backed cluster. |
| 556 | */ |
| 557 | |
| 558 | swc->swc_slot = 0; |
| 559 | swc->swc_nused = 0; |
| 560 | } |
| 561 | |
| 562 | static int |
| 563 | swapcluster_nused(struct swapcluster *swc) |
| 564 | { |
| 565 | |
| 566 | return swc->swc_nused; |
| 567 | } |
| 568 | |
| 569 | /* |
| 570 | * uvmpd_dropswap: free any swap allocated to this page. |
| 571 | * |
| 572 | * => called with owner locked. |
| 573 | * => return true if a page had an associated slot. |
| 574 | */ |
| 575 | |
| 576 | static bool |
| 577 | uvmpd_dropswap(struct vm_page *pg) |
| 578 | { |
| 579 | bool result = false; |
| 580 | struct vm_anon *anon = pg->uanon; |
| 581 | |
| 582 | if ((pg->pqflags & PQ_ANON) && anon->an_swslot) { |
| 583 | uvm_swap_free(anon->an_swslot, 1); |
| 584 | anon->an_swslot = 0; |
| 585 | pg->flags &= ~PG_CLEAN; |
| 586 | result = true; |
| 587 | } else if (pg->pqflags & PQ_AOBJ) { |
| 588 | int slot = uao_set_swslot(pg->uobject, |
| 589 | pg->offset >> PAGE_SHIFT, 0); |
| 590 | if (slot) { |
| 591 | uvm_swap_free(slot, 1); |
| 592 | pg->flags &= ~PG_CLEAN; |
| 593 | result = true; |
| 594 | } |
| 595 | } |
| 596 | |
| 597 | return result; |
| 598 | } |
| 599 | |
| 600 | /* |
| 601 | * uvmpd_trydropswap: try to free any swap allocated to this page. |
| 602 | * |
| 603 | * => return true if a slot is successfully freed. |
| 604 | */ |
| 605 | |
| 606 | bool |
| 607 | uvmpd_trydropswap(struct vm_page *pg) |
| 608 | { |
| 609 | kmutex_t *slock; |
| 610 | bool result; |
| 611 | |
| 612 | if ((pg->flags & PG_BUSY) != 0) { |
| 613 | return false; |
| 614 | } |
| 615 | |
| 616 | /* |
| 617 | * lock the page's owner. |
| 618 | */ |
| 619 | |
| 620 | slock = uvmpd_trylockowner(pg); |
| 621 | if (slock == NULL) { |
| 622 | return false; |
| 623 | } |
| 624 | |
| 625 | /* |
| 626 | * skip this page if it's busy. |
| 627 | */ |
| 628 | |
| 629 | if ((pg->flags & PG_BUSY) != 0) { |
| 630 | mutex_exit(slock); |
| 631 | return false; |
| 632 | } |
| 633 | |
| 634 | result = uvmpd_dropswap(pg); |
| 635 | |
| 636 | mutex_exit(slock); |
| 637 | |
| 638 | return result; |
| 639 | } |
| 640 | |
| 641 | #endif /* defined(VMSWAP) */ |
| 642 | |
| 643 | /* |
| 644 | * uvmpd_scan_queue: scan an replace candidate list for pages |
| 645 | * to clean or free. |
| 646 | * |
| 647 | * => called with page queues locked |
| 648 | * => we work on meeting our free target by converting inactive pages |
| 649 | * into free pages. |
| 650 | * => we handle the building of swap-backed clusters |
| 651 | */ |
| 652 | |
| 653 | static void |
| 654 | uvmpd_scan_queue(void) |
| 655 | { |
| 656 | struct vm_page *p; |
| 657 | struct uvm_object *uobj; |
| 658 | struct vm_anon *anon; |
| 659 | #if defined(VMSWAP) |
| 660 | struct swapcluster swc; |
| 661 | #endif /* defined(VMSWAP) */ |
| 662 | int dirtyreacts; |
| 663 | int lockownerfail; |
| 664 | kmutex_t *slock; |
| 665 | UVMHIST_FUNC("uvmpd_scan_queue" ); UVMHIST_CALLED(pdhist); |
| 666 | |
| 667 | /* |
| 668 | * swslot is non-zero if we are building a swap cluster. we want |
| 669 | * to stay in the loop while we have a page to scan or we have |
| 670 | * a swap-cluster to build. |
| 671 | */ |
| 672 | |
| 673 | #if defined(VMSWAP) |
| 674 | swapcluster_init(&swc); |
| 675 | #endif /* defined(VMSWAP) */ |
| 676 | |
| 677 | dirtyreacts = 0; |
| 678 | lockownerfail = 0; |
| 679 | uvmpdpol_scaninit(); |
| 680 | |
| 681 | while (/* CONSTCOND */ 1) { |
| 682 | |
| 683 | /* |
| 684 | * see if we've met the free target. |
| 685 | */ |
| 686 | |
| 687 | if (uvmexp.free + uvmexp.paging |
| 688 | #if defined(VMSWAP) |
| 689 | + swapcluster_nused(&swc) |
| 690 | #endif /* defined(VMSWAP) */ |
| 691 | >= uvmexp.freetarg << 2 || |
| 692 | dirtyreacts == UVMPD_NUMDIRTYREACTS) { |
| 693 | UVMHIST_LOG(pdhist," met free target: " |
| 694 | "exit loop" , 0, 0, 0, 0); |
| 695 | break; |
| 696 | } |
| 697 | |
| 698 | p = uvmpdpol_selectvictim(); |
| 699 | if (p == NULL) { |
| 700 | break; |
| 701 | } |
| 702 | KASSERT(uvmpdpol_pageisqueued_p(p)); |
| 703 | KASSERT(p->wire_count == 0); |
| 704 | |
| 705 | /* |
| 706 | * we are below target and have a new page to consider. |
| 707 | */ |
| 708 | |
| 709 | anon = p->uanon; |
| 710 | uobj = p->uobject; |
| 711 | |
| 712 | /* |
| 713 | * first we attempt to lock the object that this page |
| 714 | * belongs to. if our attempt fails we skip on to |
| 715 | * the next page (no harm done). it is important to |
| 716 | * "try" locking the object as we are locking in the |
| 717 | * wrong order (pageq -> object) and we don't want to |
| 718 | * deadlock. |
| 719 | * |
| 720 | * the only time we expect to see an ownerless page |
| 721 | * (i.e. a page with no uobject and !PQ_ANON) is if an |
| 722 | * anon has loaned a page from a uvm_object and the |
| 723 | * uvm_object has dropped the ownership. in that |
| 724 | * case, the anon can "take over" the loaned page |
| 725 | * and make it its own. |
| 726 | */ |
| 727 | |
| 728 | slock = uvmpd_trylockowner(p); |
| 729 | if (slock == NULL) { |
| 730 | /* |
| 731 | * yield cpu to make a chance for an LWP holding |
| 732 | * the lock run. otherwise we can busy-loop too long |
| 733 | * if the page queue is filled with a lot of pages |
| 734 | * from few objects. |
| 735 | */ |
| 736 | lockownerfail++; |
| 737 | if (lockownerfail > UVMPD_NUMTRYLOCKOWNER) { |
| 738 | mutex_exit(&uvm_pageqlock); |
| 739 | /* XXX Better than yielding but inadequate. */ |
| 740 | kpause("livelock" , false, 1, NULL); |
| 741 | mutex_enter(&uvm_pageqlock); |
| 742 | lockownerfail = 0; |
| 743 | } |
| 744 | continue; |
| 745 | } |
| 746 | if (p->flags & PG_BUSY) { |
| 747 | mutex_exit(slock); |
| 748 | uvmexp.pdbusy++; |
| 749 | continue; |
| 750 | } |
| 751 | |
| 752 | /* does the page belong to an object? */ |
| 753 | if (uobj != NULL) { |
| 754 | uvmexp.pdobscan++; |
| 755 | } else { |
| 756 | #if defined(VMSWAP) |
| 757 | KASSERT(anon != NULL); |
| 758 | uvmexp.pdanscan++; |
| 759 | #else /* defined(VMSWAP) */ |
| 760 | panic("%s: anon" , __func__); |
| 761 | #endif /* defined(VMSWAP) */ |
| 762 | } |
| 763 | |
| 764 | |
| 765 | /* |
| 766 | * we now have the object and the page queues locked. |
| 767 | * if the page is not swap-backed, call the object's |
| 768 | * pager to flush and free the page. |
| 769 | */ |
| 770 | |
| 771 | #if defined(READAHEAD_STATS) |
| 772 | if ((p->pqflags & PQ_READAHEAD) != 0) { |
| 773 | p->pqflags &= ~PQ_READAHEAD; |
| 774 | uvm_ra_miss.ev_count++; |
| 775 | } |
| 776 | #endif /* defined(READAHEAD_STATS) */ |
| 777 | |
| 778 | if ((p->pqflags & PQ_SWAPBACKED) == 0) { |
| 779 | KASSERT(uobj != NULL); |
| 780 | mutex_exit(&uvm_pageqlock); |
| 781 | (void) (uobj->pgops->pgo_put)(uobj, p->offset, |
| 782 | p->offset + PAGE_SIZE, PGO_CLEANIT|PGO_FREE); |
| 783 | mutex_enter(&uvm_pageqlock); |
| 784 | continue; |
| 785 | } |
| 786 | |
| 787 | /* |
| 788 | * the page is swap-backed. remove all the permissions |
| 789 | * from the page so we can sync the modified info |
| 790 | * without any race conditions. if the page is clean |
| 791 | * we can free it now and continue. |
| 792 | */ |
| 793 | |
| 794 | pmap_page_protect(p, VM_PROT_NONE); |
| 795 | if ((p->flags & PG_CLEAN) && pmap_clear_modify(p)) { |
| 796 | p->flags &= ~(PG_CLEAN); |
| 797 | } |
| 798 | if (p->flags & PG_CLEAN) { |
| 799 | int slot; |
| 800 | int pageidx; |
| 801 | |
| 802 | pageidx = p->offset >> PAGE_SHIFT; |
| 803 | uvm_pagefree(p); |
| 804 | uvmexp.pdfreed++; |
| 805 | |
| 806 | /* |
| 807 | * for anons, we need to remove the page |
| 808 | * from the anon ourselves. for aobjs, |
| 809 | * pagefree did that for us. |
| 810 | */ |
| 811 | |
| 812 | if (anon) { |
| 813 | KASSERT(anon->an_swslot != 0); |
| 814 | anon->an_page = NULL; |
| 815 | slot = anon->an_swslot; |
| 816 | } else { |
| 817 | slot = uao_find_swslot(uobj, pageidx); |
| 818 | } |
| 819 | mutex_exit(slock); |
| 820 | |
| 821 | if (slot > 0) { |
| 822 | /* this page is now only in swap. */ |
| 823 | mutex_enter(&uvm_swap_data_lock); |
| 824 | KASSERT(uvmexp.swpgonly < uvmexp.swpginuse); |
| 825 | uvmexp.swpgonly++; |
| 826 | mutex_exit(&uvm_swap_data_lock); |
| 827 | } |
| 828 | continue; |
| 829 | } |
| 830 | |
| 831 | #if defined(VMSWAP) |
| 832 | /* |
| 833 | * this page is dirty, skip it if we'll have met our |
| 834 | * free target when all the current pageouts complete. |
| 835 | */ |
| 836 | |
| 837 | if (uvmexp.free + uvmexp.paging > uvmexp.freetarg << 2) { |
| 838 | mutex_exit(slock); |
| 839 | continue; |
| 840 | } |
| 841 | |
| 842 | /* |
| 843 | * free any swap space allocated to the page since |
| 844 | * we'll have to write it again with its new data. |
| 845 | */ |
| 846 | |
| 847 | uvmpd_dropswap(p); |
| 848 | |
| 849 | /* |
| 850 | * start new swap pageout cluster (if necessary). |
| 851 | * |
| 852 | * if swap is full reactivate this page so that |
| 853 | * we eventually cycle all pages through the |
| 854 | * inactive queue. |
| 855 | */ |
| 856 | |
| 857 | if (swapcluster_allocslots(&swc)) { |
| 858 | dirtyreacts++; |
| 859 | uvm_pageactivate(p); |
| 860 | mutex_exit(slock); |
| 861 | continue; |
| 862 | } |
| 863 | |
| 864 | /* |
| 865 | * at this point, we're definitely going reuse this |
| 866 | * page. mark the page busy and delayed-free. |
| 867 | * we should remove the page from the page queues |
| 868 | * so we don't ever look at it again. |
| 869 | * adjust counters and such. |
| 870 | */ |
| 871 | |
| 872 | p->flags |= PG_BUSY; |
| 873 | UVM_PAGE_OWN(p, "scan_queue" ); |
| 874 | |
| 875 | p->flags |= PG_PAGEOUT; |
| 876 | uvm_pagedequeue(p); |
| 877 | |
| 878 | uvmexp.pgswapout++; |
| 879 | mutex_exit(&uvm_pageqlock); |
| 880 | |
| 881 | /* |
| 882 | * add the new page to the cluster. |
| 883 | */ |
| 884 | |
| 885 | if (swapcluster_add(&swc, p)) { |
| 886 | p->flags &= ~(PG_BUSY|PG_PAGEOUT); |
| 887 | UVM_PAGE_OWN(p, NULL); |
| 888 | mutex_enter(&uvm_pageqlock); |
| 889 | dirtyreacts++; |
| 890 | uvm_pageactivate(p); |
| 891 | mutex_exit(slock); |
| 892 | continue; |
| 893 | } |
| 894 | mutex_exit(slock); |
| 895 | |
| 896 | swapcluster_flush(&swc, false); |
| 897 | mutex_enter(&uvm_pageqlock); |
| 898 | |
| 899 | /* |
| 900 | * the pageout is in progress. bump counters and set up |
| 901 | * for the next loop. |
| 902 | */ |
| 903 | |
| 904 | uvmexp.pdpending++; |
| 905 | |
| 906 | #else /* defined(VMSWAP) */ |
| 907 | uvm_pageactivate(p); |
| 908 | mutex_exit(slock); |
| 909 | #endif /* defined(VMSWAP) */ |
| 910 | } |
| 911 | |
| 912 | #if defined(VMSWAP) |
| 913 | mutex_exit(&uvm_pageqlock); |
| 914 | swapcluster_flush(&swc, true); |
| 915 | mutex_enter(&uvm_pageqlock); |
| 916 | #endif /* defined(VMSWAP) */ |
| 917 | } |
| 918 | |
| 919 | /* |
| 920 | * uvmpd_scan: scan the page queues and attempt to meet our targets. |
| 921 | * |
| 922 | * => called with pageq's locked |
| 923 | */ |
| 924 | |
| 925 | static void |
| 926 | uvmpd_scan(void) |
| 927 | { |
| 928 | int swap_shortage, pages_freed; |
| 929 | UVMHIST_FUNC("uvmpd_scan" ); UVMHIST_CALLED(pdhist); |
| 930 | |
| 931 | uvmexp.pdrevs++; |
| 932 | |
| 933 | /* |
| 934 | * work on meeting our targets. first we work on our free target |
| 935 | * by converting inactive pages into free pages. then we work on |
| 936 | * meeting our inactive target by converting active pages to |
| 937 | * inactive ones. |
| 938 | */ |
| 939 | |
| 940 | UVMHIST_LOG(pdhist, " starting 'free' loop" ,0,0,0,0); |
| 941 | |
| 942 | pages_freed = uvmexp.pdfreed; |
| 943 | uvmpd_scan_queue(); |
| 944 | pages_freed = uvmexp.pdfreed - pages_freed; |
| 945 | |
| 946 | /* |
| 947 | * detect if we're not going to be able to page anything out |
| 948 | * until we free some swap resources from active pages. |
| 949 | */ |
| 950 | |
| 951 | swap_shortage = 0; |
| 952 | if (uvmexp.free < uvmexp.freetarg && |
| 953 | uvmexp.swpginuse >= uvmexp.swpgavail && |
| 954 | !uvm_swapisfull() && |
| 955 | pages_freed == 0) { |
| 956 | swap_shortage = uvmexp.freetarg - uvmexp.free; |
| 957 | } |
| 958 | |
| 959 | uvmpdpol_balancequeue(swap_shortage); |
| 960 | |
| 961 | /* |
| 962 | * if still below the minimum target, try unloading kernel |
| 963 | * modules. |
| 964 | */ |
| 965 | |
| 966 | if (uvmexp.free < uvmexp.freemin) { |
| 967 | module_thread_kick(); |
| 968 | } |
| 969 | } |
| 970 | |
| 971 | /* |
| 972 | * uvm_reclaimable: decide whether to wait for pagedaemon. |
| 973 | * |
| 974 | * => return true if it seems to be worth to do uvm_wait. |
| 975 | * |
| 976 | * XXX should be tunable. |
| 977 | * XXX should consider pools, etc? |
| 978 | */ |
| 979 | |
| 980 | bool |
| 981 | uvm_reclaimable(void) |
| 982 | { |
| 983 | int filepages; |
| 984 | int active, inactive; |
| 985 | |
| 986 | /* |
| 987 | * if swap is not full, no problem. |
| 988 | */ |
| 989 | |
| 990 | if (!uvm_swapisfull()) { |
| 991 | return true; |
| 992 | } |
| 993 | |
| 994 | /* |
| 995 | * file-backed pages can be reclaimed even when swap is full. |
| 996 | * if we have more than 1/16 of pageable memory or 5MB, try to reclaim. |
| 997 | * |
| 998 | * XXX assume the worst case, ie. all wired pages are file-backed. |
| 999 | * |
| 1000 | * XXX should consider about other reclaimable memory. |
| 1001 | * XXX ie. pools, traditional buffer cache. |
| 1002 | */ |
| 1003 | |
| 1004 | filepages = uvmexp.filepages + uvmexp.execpages - uvmexp.wired; |
| 1005 | uvm_estimatepageable(&active, &inactive); |
| 1006 | if (filepages >= MIN((active + inactive) >> 4, |
| 1007 | 5 * 1024 * 1024 >> PAGE_SHIFT)) { |
| 1008 | return true; |
| 1009 | } |
| 1010 | |
| 1011 | /* |
| 1012 | * kill the process, fail allocation, etc.. |
| 1013 | */ |
| 1014 | |
| 1015 | return false; |
| 1016 | } |
| 1017 | |
| 1018 | void |
| 1019 | uvm_estimatepageable(int *active, int *inactive) |
| 1020 | { |
| 1021 | |
| 1022 | uvmpdpol_estimatepageable(active, inactive); |
| 1023 | } |
| 1024 | |
| 1025 | |