1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * The Mach Operating System project at Carnegie-Mellon University. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 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 the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * from: @(#)vm_glue.c 8.6 (Berkeley) 1/5/94 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 * $FreeBSD: src/sys/vm/vm_glue.c,v 1.94.2.4 2003/01/13 22:51:17 dillon Exp $ 65 * $DragonFly: src/sys/vm/vm_glue.c,v 1.56 2008/07/01 02:02:56 dillon Exp $ 66 */ 67 68 #include "opt_vm.h" 69 70 #include <sys/param.h> 71 #include <sys/systm.h> 72 #include <sys/proc.h> 73 #include <sys/resourcevar.h> 74 #include <sys/buf.h> 75 #include <sys/shm.h> 76 #include <sys/vmmeter.h> 77 #include <sys/sysctl.h> 78 79 #include <sys/kernel.h> 80 #include <sys/unistd.h> 81 82 #include <machine/limits.h> 83 84 #include <vm/vm.h> 85 #include <vm/vm_param.h> 86 #include <sys/lock.h> 87 #include <vm/pmap.h> 88 #include <vm/vm_map.h> 89 #include <vm/vm_page.h> 90 #include <vm/vm_pageout.h> 91 #include <vm/vm_kern.h> 92 #include <vm/vm_extern.h> 93 94 #include <sys/user.h> 95 #include <vm/vm_page2.h> 96 #include <sys/thread2.h> 97 #include <sys/sysref2.h> 98 99 /* 100 * THIS MUST BE THE LAST INITIALIZATION ITEM!!! 101 * 102 * Note: run scheduling should be divorced from the vm system. 103 */ 104 static void scheduler (void *); 105 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, scheduler, NULL) 106 107 #ifdef INVARIANTS 108 109 static int swap_debug = 0; 110 SYSCTL_INT(_vm, OID_AUTO, swap_debug, 111 CTLFLAG_RW, &swap_debug, 0, ""); 112 113 #endif 114 115 static int scheduler_notify; 116 117 static void swapout (struct proc *); 118 119 /* 120 * No requirements. 121 */ 122 int 123 kernacc(c_caddr_t addr, int len, int rw) 124 { 125 boolean_t rv; 126 vm_offset_t saddr, eaddr; 127 vm_prot_t prot; 128 129 KASSERT((rw & (~VM_PROT_ALL)) == 0, 130 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 131 132 /* 133 * The globaldata space is not part of the kernel_map proper, 134 * check access separately. 135 */ 136 if (is_globaldata_space((vm_offset_t)addr, (vm_offset_t)(addr + len))) 137 return (TRUE); 138 139 /* 140 * Nominal kernel memory access - check access via kernel_map. 141 */ 142 if ((vm_offset_t)addr + len > kernel_map.max_offset || 143 (vm_offset_t)addr + len < (vm_offset_t)addr) { 144 return (FALSE); 145 } 146 prot = rw; 147 saddr = trunc_page((vm_offset_t)addr); 148 eaddr = round_page((vm_offset_t)addr + len); 149 rv = vm_map_check_protection(&kernel_map, saddr, eaddr, prot, FALSE); 150 151 return (rv == TRUE); 152 } 153 154 /* 155 * No requirements. 156 */ 157 int 158 useracc(c_caddr_t addr, int len, int rw) 159 { 160 boolean_t rv; 161 vm_prot_t prot; 162 vm_map_t map; 163 vm_map_entry_t save_hint; 164 vm_offset_t wrap; 165 166 KASSERT((rw & (~VM_PROT_ALL)) == 0, 167 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 168 prot = rw; 169 /* 170 * XXX - check separately to disallow access to user area and user 171 * page tables - they are in the map. 172 */ 173 wrap = (vm_offset_t)addr + len; 174 if (wrap > VM_MAX_USER_ADDRESS || wrap < (vm_offset_t)addr) { 175 return (FALSE); 176 } 177 map = &curproc->p_vmspace->vm_map; 178 vm_map_lock_read(map); 179 /* 180 * We save the map hint, and restore it. Useracc appears to distort 181 * the map hint unnecessarily. 182 */ 183 save_hint = map->hint; 184 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 185 round_page(wrap), prot, TRUE); 186 map->hint = save_hint; 187 vm_map_unlock_read(map); 188 189 return (rv == TRUE); 190 } 191 192 /* 193 * No requirements. 194 */ 195 void 196 vslock(caddr_t addr, u_int len) 197 { 198 if (len) { 199 vm_map_wire(&curproc->p_vmspace->vm_map, 200 trunc_page((vm_offset_t)addr), 201 round_page((vm_offset_t)addr + len), 0); 202 } 203 } 204 205 /* 206 * No requirements. 207 */ 208 void 209 vsunlock(caddr_t addr, u_int len) 210 { 211 if (len) { 212 vm_map_wire(&curproc->p_vmspace->vm_map, 213 trunc_page((vm_offset_t)addr), 214 round_page((vm_offset_t)addr + len), 215 KM_PAGEABLE); 216 } 217 } 218 219 /* 220 * Implement fork's actions on an address space. 221 * Here we arrange for the address space to be copied or referenced, 222 * allocate a user struct (pcb and kernel stack), then call the 223 * machine-dependent layer to fill those in and make the new process 224 * ready to run. The new process is set up so that it returns directly 225 * to user mode to avoid stack copying and relocation problems. 226 * 227 * No requirements. 228 */ 229 void 230 vm_fork(struct proc *p1, struct proc *p2, int flags) 231 { 232 if ((flags & RFPROC) == 0) { 233 /* 234 * Divorce the memory, if it is shared, essentially 235 * this changes shared memory amongst threads, into 236 * COW locally. 237 */ 238 if ((flags & RFMEM) == 0) { 239 if (p1->p_vmspace->vm_sysref.refcnt > 1) { 240 vmspace_unshare(p1); 241 } 242 } 243 cpu_fork(ONLY_LWP_IN_PROC(p1), NULL, flags); 244 return; 245 } 246 247 if (flags & RFMEM) { 248 vmspace_ref(p1->p_vmspace); 249 p2->p_vmspace = p1->p_vmspace; 250 } 251 252 while (vm_page_count_severe()) { 253 vm_wait(0); 254 } 255 256 if ((flags & RFMEM) == 0) { 257 p2->p_vmspace = vmspace_fork(p1->p_vmspace); 258 259 pmap_pinit2(vmspace_pmap(p2->p_vmspace)); 260 261 if (p1->p_vmspace->vm_shm) 262 shmfork(p1, p2); 263 } 264 265 pmap_init_proc(p2); 266 } 267 268 /* 269 * Set default limits for VM system. Call during proc0's initialization. 270 * 271 * Called from the low level boot code only. 272 */ 273 void 274 vm_init_limits(struct proc *p) 275 { 276 int rss_limit; 277 278 /* 279 * Set up the initial limits on process VM. Set the maximum resident 280 * set size to be half of (reasonably) available memory. Since this 281 * is a soft limit, it comes into effect only when the system is out 282 * of memory - half of main memory helps to favor smaller processes, 283 * and reduces thrashing of the object cache. 284 */ 285 p->p_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 286 p->p_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 287 p->p_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 288 p->p_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 289 /* limit the limit to no less than 2MB */ 290 rss_limit = max(vmstats.v_free_count, 512); 291 p->p_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 292 p->p_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 293 } 294 295 /* 296 * Faultin the specified process. Note that the process can be in any 297 * state. Just clear P_SWAPPEDOUT and call wakeup in case the process is 298 * sleeping. 299 * 300 * No requirements. 301 */ 302 void 303 faultin(struct proc *p) 304 { 305 if (p->p_flags & P_SWAPPEDOUT) { 306 /* 307 * The process is waiting in the kernel to return to user 308 * mode but cannot until P_SWAPPEDOUT gets cleared. 309 */ 310 lwkt_gettoken(&p->p_token); 311 p->p_flags &= ~(P_SWAPPEDOUT | P_SWAPWAIT); 312 #ifdef INVARIANTS 313 if (swap_debug) 314 kprintf("swapping in %d (%s)\n", p->p_pid, p->p_comm); 315 #endif 316 wakeup(p); 317 lwkt_reltoken(&p->p_token); 318 } 319 } 320 321 /* 322 * Kernel initialization eventually falls through to this function, 323 * which is process 0. 324 * 325 * This swapin algorithm attempts to swap-in processes only if there 326 * is enough space for them. Of course, if a process waits for a long 327 * time, it will be swapped in anyway. 328 */ 329 struct scheduler_info { 330 struct proc *pp; 331 int ppri; 332 }; 333 334 static int scheduler_callback(struct proc *p, void *data); 335 336 static void 337 scheduler(void *dummy) 338 { 339 struct scheduler_info info; 340 struct proc *p; 341 342 KKASSERT(!IN_CRITICAL_SECT(curthread)); 343 loop: 344 scheduler_notify = 0; 345 /* 346 * Don't try to swap anything in if we are low on memory. 347 */ 348 if (vm_page_count_severe()) { 349 vm_wait(0); 350 goto loop; 351 } 352 353 /* 354 * Look for a good candidate to wake up 355 */ 356 info.pp = NULL; 357 info.ppri = INT_MIN; 358 allproc_scan(scheduler_callback, &info); 359 360 /* 361 * Nothing to do, back to sleep for at least 1/10 of a second. If 362 * we are woken up, immediately process the next request. If 363 * multiple requests have built up the first is processed 364 * immediately and the rest are staggered. 365 */ 366 if ((p = info.pp) == NULL) { 367 tsleep(&proc0, 0, "nowork", hz / 10); 368 if (scheduler_notify == 0) 369 tsleep(&scheduler_notify, 0, "nowork", 0); 370 goto loop; 371 } 372 373 /* 374 * Fault the selected process in, then wait for a short period of 375 * time and loop up. 376 * 377 * XXX we need a heuristic to get a measure of system stress and 378 * then adjust our stagger wakeup delay accordingly. 379 */ 380 lwkt_gettoken(&proc_token); 381 faultin(p); 382 p->p_swtime = 0; 383 PRELE(p); 384 lwkt_reltoken(&proc_token); 385 tsleep(&proc0, 0, "swapin", hz / 10); 386 goto loop; 387 } 388 389 /* 390 * The caller must hold proc_token. 391 */ 392 static int 393 scheduler_callback(struct proc *p, void *data) 394 { 395 struct scheduler_info *info = data; 396 struct lwp *lp; 397 segsz_t pgs; 398 int pri; 399 400 if (p->p_flags & P_SWAPWAIT) { 401 pri = 0; 402 FOREACH_LWP_IN_PROC(lp, p) { 403 /* XXX lwp might need a different metric */ 404 pri += lp->lwp_slptime; 405 } 406 pri += p->p_swtime - p->p_nice * 8; 407 408 /* 409 * The more pages paged out while we were swapped, 410 * the more work we have to do to get up and running 411 * again and the lower our wakeup priority. 412 * 413 * Each second of sleep time is worth ~1MB 414 */ 415 lwkt_gettoken(&p->p_vmspace->vm_map.token); 416 pgs = vmspace_resident_count(p->p_vmspace); 417 if (pgs < p->p_vmspace->vm_swrss) { 418 pri -= (p->p_vmspace->vm_swrss - pgs) / 419 (1024 * 1024 / PAGE_SIZE); 420 } 421 lwkt_reltoken(&p->p_vmspace->vm_map.token); 422 423 /* 424 * If this process is higher priority and there is 425 * enough space, then select this process instead of 426 * the previous selection. 427 */ 428 if (pri > info->ppri) { 429 if (info->pp) 430 PRELE(info->pp); 431 PHOLD(p); 432 info->pp = p; 433 info->ppri = pri; 434 } 435 } 436 return(0); 437 } 438 439 /* 440 * SMP races ok. 441 * No requirements. 442 */ 443 void 444 swapin_request(void) 445 { 446 if (scheduler_notify == 0) { 447 scheduler_notify = 1; 448 wakeup(&scheduler_notify); 449 } 450 } 451 452 #ifndef NO_SWAPPING 453 454 #define swappable(p) \ 455 (((p)->p_lock == 0) && \ 456 ((p)->p_flags & (P_TRACED|P_SYSTEM|P_SWAPPEDOUT|P_WEXIT)) == 0) 457 458 459 /* 460 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 461 */ 462 static int swap_idle_threshold1 = 15; 463 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, 464 CTLFLAG_RW, &swap_idle_threshold1, 0, "Guaranteed process resident time (sec)"); 465 466 /* 467 * Swap_idle_threshold2 is the time that a process can be idle before 468 * it will be swapped out, if idle swapping is enabled. Default is 469 * one minute. 470 */ 471 static int swap_idle_threshold2 = 60; 472 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, 473 CTLFLAG_RW, &swap_idle_threshold2, 0, "Time (sec) a process can idle before being swapped"); 474 475 /* 476 * Swapout is driven by the pageout daemon. Very simple, we find eligible 477 * procs and mark them as being swapped out. This will cause the kernel 478 * to prefer to pageout those proc's pages first and the procs in question 479 * will not return to user mode until the swapper tells them they can. 480 * 481 * If any procs have been sleeping/stopped for at least maxslp seconds, 482 * they are swapped. Else, we swap the longest-sleeping or stopped process, 483 * if any, otherwise the longest-resident process. 484 */ 485 486 static int swapout_procs_callback(struct proc *p, void *data); 487 488 /* 489 * No requirements. 490 */ 491 void 492 swapout_procs(int action) 493 { 494 allproc_scan(swapout_procs_callback, &action); 495 } 496 497 /* 498 * The caller must hold proc_token 499 */ 500 static int 501 swapout_procs_callback(struct proc *p, void *data) 502 { 503 struct vmspace *vm; 504 struct lwp *lp; 505 int action = *(int *)data; 506 int minslp = -1; 507 508 if (!swappable(p)) 509 return(0); 510 511 lwkt_gettoken(&p->p_token); 512 vm = p->p_vmspace; 513 514 /* 515 * We only consider active processes. 516 */ 517 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) { 518 lwkt_reltoken(&p->p_token); 519 return(0); 520 } 521 522 FOREACH_LWP_IN_PROC(lp, p) { 523 /* 524 * do not swap out a realtime process 525 */ 526 if (RTP_PRIO_IS_REALTIME(lp->lwp_rtprio.type)) { 527 lwkt_reltoken(&p->p_token); 528 return(0); 529 } 530 531 /* 532 * Guarentee swap_idle_threshold time in memory 533 */ 534 if (lp->lwp_slptime < swap_idle_threshold1) { 535 lwkt_reltoken(&p->p_token); 536 return(0); 537 } 538 539 /* 540 * If the system is under memory stress, or if we 541 * are swapping idle processes >= swap_idle_threshold2, 542 * then swap the process out. 543 */ 544 if (((action & VM_SWAP_NORMAL) == 0) && 545 (((action & VM_SWAP_IDLE) == 0) || 546 (lp->lwp_slptime < swap_idle_threshold2))) { 547 lwkt_reltoken(&p->p_token); 548 return(0); 549 } 550 551 if (minslp == -1 || lp->lwp_slptime < minslp) 552 minslp = lp->lwp_slptime; 553 } 554 555 /* 556 * If the process has been asleep for awhile, swap 557 * it out. 558 */ 559 if ((action & VM_SWAP_NORMAL) || 560 ((action & VM_SWAP_IDLE) && 561 (minslp > swap_idle_threshold2))) { 562 swapout(p); 563 } 564 565 /* 566 * cleanup our reference 567 */ 568 lwkt_reltoken(&p->p_token); 569 570 return(0); 571 } 572 573 /* 574 * The caller must hold proc_token and p->p_token 575 */ 576 static void 577 swapout(struct proc *p) 578 { 579 #ifdef INVARIANTS 580 if (swap_debug) 581 kprintf("swapping out %d (%s)\n", p->p_pid, p->p_comm); 582 #endif 583 ++p->p_ru.ru_nswap; 584 585 /* 586 * remember the process resident count 587 */ 588 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 589 p->p_flags |= P_SWAPPEDOUT; 590 p->p_swtime = 0; 591 } 592 593 #endif /* !NO_SWAPPING */ 594 595