1 /* 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * The Mach Operating System project at Carnegie-Mellon University. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. 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 * from: @(#)vm_glue.c 8.6 (Berkeley) 1/5/94 37 * 38 * 39 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 40 * All rights reserved. 41 * 42 * Permission to use, copy, modify and distribute this software and 43 * its documentation is hereby granted, provided that both the copyright 44 * notice and this permission notice appear in all copies of the 45 * software, derivative works or modified versions, and any portions 46 * thereof, and that both notices appear in supporting documentation. 47 * 48 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 49 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 50 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 51 * 52 * Carnegie Mellon requests users of this software to return to 53 * 54 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 55 * School of Computer Science 56 * Carnegie Mellon University 57 * Pittsburgh PA 15213-3890 58 * 59 * any improvements or extensions that they make and grant Carnegie the 60 * rights to redistribute these changes. 61 * 62 * $FreeBSD: src/sys/vm/vm_glue.c,v 1.94.2.4 2003/01/13 22:51:17 dillon Exp $ 63 * $DragonFly: src/sys/vm/vm_glue.c,v 1.56 2008/07/01 02:02:56 dillon Exp $ 64 */ 65 66 #include "opt_vm.h" 67 68 #include <sys/param.h> 69 #include <sys/systm.h> 70 #include <sys/proc.h> 71 #include <sys/resourcevar.h> 72 #include <sys/buf.h> 73 #include <sys/shm.h> 74 #include <sys/vmmeter.h> 75 #include <sys/sysctl.h> 76 77 #include <sys/kernel.h> 78 #include <sys/unistd.h> 79 80 #include <machine/limits.h> 81 82 #include <vm/vm.h> 83 #include <vm/vm_param.h> 84 #include <sys/lock.h> 85 #include <vm/pmap.h> 86 #include <vm/vm_map.h> 87 #include <vm/vm_page.h> 88 #include <vm/vm_pageout.h> 89 #include <vm/vm_kern.h> 90 #include <vm/vm_extern.h> 91 92 #include <sys/user.h> 93 #include <vm/vm_page2.h> 94 #include <sys/thread2.h> 95 #include <sys/sysref2.h> 96 97 /* 98 * THIS MUST BE THE LAST INITIALIZATION ITEM!!! 99 * 100 * Note: run scheduling should be divorced from the vm system. 101 */ 102 static void scheduler (void *); 103 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, scheduler, NULL) 104 105 #ifdef INVARIANTS 106 107 static int swap_debug = 0; 108 SYSCTL_INT(_vm, OID_AUTO, swap_debug, 109 CTLFLAG_RW, &swap_debug, 0, ""); 110 111 #endif 112 113 static int scheduler_notify; 114 115 static void swapout (struct proc *); 116 117 int 118 kernacc(c_caddr_t addr, int len, int rw) 119 { 120 boolean_t rv; 121 vm_offset_t saddr, eaddr; 122 vm_prot_t prot; 123 124 KASSERT((rw & (~VM_PROT_ALL)) == 0, 125 ("illegal ``rw'' argument to kernacc (%x)\n", rw)); 126 127 /* 128 * The globaldata space is not part of the kernel_map proper, 129 * check access separately. 130 */ 131 if (is_globaldata_space((vm_offset_t)addr, (vm_offset_t)(addr + len))) 132 return (TRUE); 133 134 /* 135 * Nominal kernel memory access - check access via kernel_map. 136 */ 137 if ((vm_offset_t)addr + len > kernel_map.max_offset || 138 (vm_offset_t)addr + len < (vm_offset_t)addr) { 139 return (FALSE); 140 } 141 prot = rw; 142 saddr = trunc_page((vm_offset_t)addr); 143 eaddr = round_page((vm_offset_t)addr + len); 144 vm_map_lock_read(&kernel_map); 145 rv = vm_map_check_protection(&kernel_map, saddr, eaddr, prot); 146 vm_map_unlock_read(&kernel_map); 147 return (rv == TRUE); 148 } 149 150 int 151 useracc(c_caddr_t addr, int len, int rw) 152 { 153 boolean_t rv; 154 vm_prot_t prot; 155 vm_map_t map; 156 vm_map_entry_t save_hint; 157 158 KASSERT((rw & (~VM_PROT_ALL)) == 0, 159 ("illegal ``rw'' argument to useracc (%x)\n", rw)); 160 prot = rw; 161 /* 162 * XXX - check separately to disallow access to user area and user 163 * page tables - they are in the map. 164 * 165 * XXX - VM_MAX_USER_ADDRESS is an end address, not a max. It was once 166 * only used (as an end address) in trap.c. Use it as an end address 167 * here too. This bogusness has spread. I just fixed where it was 168 * used as a max in vm_mmap.c. 169 */ 170 if ((vm_offset_t) addr + len > /* XXX */ VM_MAX_USER_ADDRESS 171 || (vm_offset_t) addr + len < (vm_offset_t) addr) { 172 return (FALSE); 173 } 174 map = &curproc->p_vmspace->vm_map; 175 vm_map_lock_read(map); 176 /* 177 * We save the map hint, and restore it. Useracc appears to distort 178 * the map hint unnecessarily. 179 */ 180 save_hint = map->hint; 181 rv = vm_map_check_protection(map, 182 trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len), prot); 183 map->hint = save_hint; 184 vm_map_unlock_read(map); 185 186 return (rv == TRUE); 187 } 188 189 void 190 vslock(caddr_t addr, u_int len) 191 { 192 if (len) { 193 vm_map_wire(&curproc->p_vmspace->vm_map, 194 trunc_page((vm_offset_t)addr), 195 round_page((vm_offset_t)addr + len), 0); 196 } 197 } 198 199 void 200 vsunlock(caddr_t addr, u_int len) 201 { 202 if (len) { 203 vm_map_wire(&curproc->p_vmspace->vm_map, 204 trunc_page((vm_offset_t)addr), 205 round_page((vm_offset_t)addr + len), 206 KM_PAGEABLE); 207 } 208 } 209 210 /* 211 * Implement fork's actions on an address space. 212 * Here we arrange for the address space to be copied or referenced, 213 * allocate a user struct (pcb and kernel stack), then call the 214 * machine-dependent layer to fill those in and make the new process 215 * ready to run. The new process is set up so that it returns directly 216 * to user mode to avoid stack copying and relocation problems. 217 */ 218 void 219 vm_fork(struct proc *p1, struct proc *p2, int flags) 220 { 221 if ((flags & RFPROC) == 0) { 222 /* 223 * Divorce the memory, if it is shared, essentially 224 * this changes shared memory amongst threads, into 225 * COW locally. 226 */ 227 if ((flags & RFMEM) == 0) { 228 if (p1->p_vmspace->vm_sysref.refcnt > 1) { 229 vmspace_unshare(p1); 230 } 231 } 232 cpu_fork(ONLY_LWP_IN_PROC(p1), NULL, flags); 233 return; 234 } 235 236 if (flags & RFMEM) { 237 p2->p_vmspace = p1->p_vmspace; 238 sysref_get(&p1->p_vmspace->vm_sysref); 239 } 240 241 while (vm_page_count_severe()) { 242 vm_wait(0); 243 } 244 245 if ((flags & RFMEM) == 0) { 246 p2->p_vmspace = vmspace_fork(p1->p_vmspace); 247 248 pmap_pinit2(vmspace_pmap(p2->p_vmspace)); 249 250 if (p1->p_vmspace->vm_shm) 251 shmfork(p1, p2); 252 } 253 254 pmap_init_proc(p2); 255 } 256 257 /* 258 * Called after process has been wait(2)'ed apon and is being reaped. 259 * The idea is to reclaim resources that we could not reclaim while 260 * the process was still executing. 261 */ 262 void 263 vm_waitproc(struct proc *p) 264 { 265 cpu_proc_wait(p); 266 vmspace_exitfree(p); /* and clean-out the vmspace */ 267 } 268 269 /* 270 * Set default limits for VM system. Call during proc0's initialization. 271 */ 272 void 273 vm_init_limits(struct proc *p) 274 { 275 int rss_limit; 276 277 /* 278 * Set up the initial limits on process VM. Set the maximum resident 279 * set size to be half of (reasonably) available memory. Since this 280 * is a soft limit, it comes into effect only when the system is out 281 * of memory - half of main memory helps to favor smaller processes, 282 * and reduces thrashing of the object cache. 283 */ 284 p->p_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 285 p->p_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 286 p->p_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 287 p->p_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 288 /* limit the limit to no less than 2MB */ 289 rss_limit = max(vmstats.v_free_count, 512); 290 p->p_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 291 p->p_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 292 } 293 294 /* 295 * Faultin the specified process. Note that the process can be in any 296 * state. Just clear P_SWAPPEDOUT and call wakeup in case the process is 297 * sleeping. 298 */ 299 void 300 faultin(struct proc *p) 301 { 302 if (p->p_flag & P_SWAPPEDOUT) { 303 /* 304 * The process is waiting in the kernel to return to user 305 * mode but cannot until P_SWAPPEDOUT gets cleared. 306 */ 307 crit_enter(); 308 p->p_flag &= ~(P_SWAPPEDOUT | P_SWAPWAIT); 309 #ifdef INVARIANTS 310 if (swap_debug) 311 kprintf("swapping in %d (%s)\n", p->p_pid, p->p_comm); 312 #endif 313 wakeup(p); 314 315 crit_exit(); 316 } 317 } 318 319 /* 320 * Kernel initialization eventually falls through to this function, 321 * which is process 0. 322 * 323 * This swapin algorithm attempts to swap-in processes only if there 324 * is enough space for them. Of course, if a process waits for a long 325 * time, it will be swapped in anyway. 326 */ 327 328 struct scheduler_info { 329 struct proc *pp; 330 int ppri; 331 }; 332 333 static int scheduler_callback(struct proc *p, void *data); 334 335 static void 336 scheduler(void *dummy) 337 { 338 struct scheduler_info info; 339 struct proc *p; 340 341 KKASSERT(!IN_CRITICAL_SECT(curthread)); 342 loop: 343 scheduler_notify = 0; 344 /* 345 * Don't try to swap anything in if we are low on memory. 346 */ 347 if (vm_page_count_severe()) { 348 vm_wait(0); 349 goto loop; 350 } 351 352 /* 353 * Look for a good candidate to wake up 354 */ 355 info.pp = NULL; 356 info.ppri = INT_MIN; 357 allproc_scan(scheduler_callback, &info); 358 359 /* 360 * Nothing to do, back to sleep for at least 1/10 of a second. If 361 * we are woken up, immediately process the next request. If 362 * multiple requests have built up the first is processed 363 * immediately and the rest are staggered. 364 */ 365 if ((p = info.pp) == NULL) { 366 tsleep(&proc0, 0, "nowork", hz / 10); 367 if (scheduler_notify == 0) 368 tsleep(&scheduler_notify, 0, "nowork", 0); 369 goto loop; 370 } 371 372 /* 373 * Fault the selected process in, then wait for a short period of 374 * time and loop up. 375 * 376 * XXX we need a heuristic to get a measure of system stress and 377 * then adjust our stagger wakeup delay accordingly. 378 */ 379 faultin(p); 380 p->p_swtime = 0; 381 PRELE(p); 382 tsleep(&proc0, 0, "swapin", hz / 10); 383 goto loop; 384 } 385 386 static int 387 scheduler_callback(struct proc *p, void *data) 388 { 389 struct scheduler_info *info = data; 390 struct lwp *lp; 391 segsz_t pgs; 392 int pri; 393 394 if (p->p_flag & P_SWAPWAIT) { 395 pri = 0; 396 FOREACH_LWP_IN_PROC(lp, p) { 397 /* XXX lwp might need a different metric */ 398 pri += lp->lwp_slptime; 399 } 400 pri += p->p_swtime - p->p_nice * 8; 401 402 /* 403 * The more pages paged out while we were swapped, 404 * the more work we have to do to get up and running 405 * again and the lower our wakeup priority. 406 * 407 * Each second of sleep time is worth ~1MB 408 */ 409 pgs = vmspace_resident_count(p->p_vmspace); 410 if (pgs < p->p_vmspace->vm_swrss) { 411 pri -= (p->p_vmspace->vm_swrss - pgs) / 412 (1024 * 1024 / PAGE_SIZE); 413 } 414 415 /* 416 * If this process is higher priority and there is 417 * enough space, then select this process instead of 418 * the previous selection. 419 */ 420 if (pri > info->ppri) { 421 if (info->pp) 422 PRELE(info->pp); 423 PHOLD(p); 424 info->pp = p; 425 info->ppri = pri; 426 } 427 } 428 return(0); 429 } 430 431 void 432 swapin_request(void) 433 { 434 if (scheduler_notify == 0) { 435 scheduler_notify = 1; 436 wakeup(&scheduler_notify); 437 } 438 } 439 440 #ifndef NO_SWAPPING 441 442 #define swappable(p) \ 443 (((p)->p_lock == 0) && \ 444 ((p)->p_flag & (P_TRACED|P_SYSTEM|P_SWAPPEDOUT|P_WEXIT)) == 0) 445 446 447 /* 448 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 449 */ 450 static int swap_idle_threshold1 = 15; 451 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, 452 CTLFLAG_RW, &swap_idle_threshold1, 0, ""); 453 454 /* 455 * Swap_idle_threshold2 is the time that a process can be idle before 456 * it will be swapped out, if idle swapping is enabled. Default is 457 * one minute. 458 */ 459 static int swap_idle_threshold2 = 60; 460 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, 461 CTLFLAG_RW, &swap_idle_threshold2, 0, ""); 462 463 /* 464 * Swapout is driven by the pageout daemon. Very simple, we find eligible 465 * procs and mark them as being swapped out. This will cause the kernel 466 * to prefer to pageout those proc's pages first and the procs in question 467 * will not return to user mode until the swapper tells them they can. 468 * 469 * If any procs have been sleeping/stopped for at least maxslp seconds, 470 * they are swapped. Else, we swap the longest-sleeping or stopped process, 471 * if any, otherwise the longest-resident process. 472 */ 473 474 static int swapout_procs_callback(struct proc *p, void *data); 475 476 void 477 swapout_procs(int action) 478 { 479 allproc_scan(swapout_procs_callback, &action); 480 } 481 482 static int 483 swapout_procs_callback(struct proc *p, void *data) 484 { 485 struct vmspace *vm; 486 struct lwp *lp; 487 int action = *(int *)data; 488 int minslp = -1; 489 490 if (!swappable(p)) 491 return(0); 492 493 vm = p->p_vmspace; 494 495 /* 496 * We only consider active processes. 497 */ 498 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) 499 return(0); 500 501 FOREACH_LWP_IN_PROC(lp, p) { 502 /* 503 * do not swap out a realtime process 504 */ 505 if (RTP_PRIO_IS_REALTIME(lp->lwp_rtprio.type)) 506 return(0); 507 508 /* 509 * Guarentee swap_idle_threshold time in memory 510 */ 511 if (lp->lwp_slptime < swap_idle_threshold1) 512 return(0); 513 514 /* 515 * If the system is under memory stress, or if we 516 * are swapping idle processes >= swap_idle_threshold2, 517 * then swap the process out. 518 */ 519 if (((action & VM_SWAP_NORMAL) == 0) && 520 (((action & VM_SWAP_IDLE) == 0) || 521 (lp->lwp_slptime < swap_idle_threshold2))) { 522 return(0); 523 } 524 525 if (minslp == -1 || lp->lwp_slptime < minslp) 526 minslp = lp->lwp_slptime; 527 } 528 529 sysref_get(&vm->vm_sysref); 530 531 /* 532 * If the process has been asleep for awhile, swap 533 * it out. 534 */ 535 if ((action & VM_SWAP_NORMAL) || 536 ((action & VM_SWAP_IDLE) && 537 (minslp > swap_idle_threshold2))) { 538 swapout(p); 539 } 540 541 /* 542 * cleanup our reference 543 */ 544 sysref_put(&vm->vm_sysref); 545 546 return(0); 547 } 548 549 static void 550 swapout(struct proc *p) 551 { 552 #ifdef INVARIANTS 553 if (swap_debug) 554 kprintf("swapping out %d (%s)\n", p->p_pid, p->p_comm); 555 #endif 556 ++p->p_ru.ru_nswap; 557 /* 558 * remember the process resident count 559 */ 560 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 561 p->p_flag |= P_SWAPPEDOUT; 562 p->p_swtime = 0; 563 } 564 565 #endif /* !NO_SWAPPING */ 566 567