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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * from: @(#)vm_glue.c 8.6 (Berkeley) 1/5/94 35 * 36 * 37 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 38 * All rights reserved. 39 * 40 * Permission to use, copy, modify and distribute this software and 41 * its documentation is hereby granted, provided that both the copyright 42 * notice and this permission notice appear in all copies of the 43 * software, derivative works or modified versions, and any portions 44 * thereof, and that both notices appear in supporting documentation. 45 * 46 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 47 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 48 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 49 * 50 * Carnegie Mellon requests users of this software to return to 51 * 52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 53 * School of Computer Science 54 * Carnegie Mellon University 55 * Pittsburgh PA 15213-3890 56 * 57 * any improvements or extensions that they make and grant Carnegie the 58 * rights to redistribute these changes. 59 * 60 * $FreeBSD: src/sys/vm/vm_glue.c,v 1.94.2.4 2003/01/13 22:51:17 dillon Exp $ 61 */ 62 63 #include "opt_vm.h" 64 65 #include <sys/param.h> 66 #include <sys/systm.h> 67 #include <sys/proc.h> 68 #include <sys/resourcevar.h> 69 #include <sys/buf.h> 70 #include <sys/shm.h> 71 #include <sys/vmmeter.h> 72 #include <sys/sysctl.h> 73 74 #include <sys/kernel.h> 75 #include <sys/unistd.h> 76 77 #include <machine/limits.h> 78 #include <machine/vmm.h> 79 80 #include <vm/vm.h> 81 #include <vm/vm_param.h> 82 #include <sys/lock.h> 83 #include <vm/pmap.h> 84 #include <vm/vm_map.h> 85 #include <vm/vm_page.h> 86 #include <vm/vm_pageout.h> 87 #include <vm/vm_kern.h> 88 #include <vm/vm_extern.h> 89 90 #include <sys/user.h> 91 #include <vm/vm_page2.h> 92 #include <sys/thread2.h> 93 #include <sys/sysref2.h> 94 95 /* 96 * THIS MUST BE THE LAST INITIALIZATION ITEM!!! 97 * 98 * Note: run scheduling should be divorced from the vm system. 99 */ 100 static void scheduler (void *); 101 SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, scheduler, NULL); 102 103 #ifdef INVARIANTS 104 105 static int swap_debug = 0; 106 SYSCTL_INT(_vm, OID_AUTO, swap_debug, 107 CTLFLAG_RW, &swap_debug, 0, ""); 108 109 #endif 110 111 static int scheduler_notify; 112 113 static void swapout (struct proc *); 114 115 /* 116 * No requirements. 117 */ 118 int 119 kernacc(c_caddr_t addr, int len, int rw) 120 { 121 boolean_t rv; 122 vm_offset_t saddr, eaddr; 123 vm_prot_t prot; 124 125 KASSERT((rw & (~VM_PROT_ALL)) == 0, 126 ("illegal ``rw'' argument to kernacc (%x)", rw)); 127 128 /* 129 * The globaldata space is not part of the kernel_map proper, 130 * check access separately. 131 */ 132 if (is_globaldata_space((vm_offset_t)addr, (vm_offset_t)(addr + len))) 133 return (TRUE); 134 135 /* 136 * Nominal kernel memory access - check access via kernel_map. 137 */ 138 if ((vm_offset_t)addr + len > kernel_map.max_offset || 139 (vm_offset_t)addr + len < (vm_offset_t)addr) { 140 return (FALSE); 141 } 142 prot = rw; 143 saddr = trunc_page((vm_offset_t)addr); 144 eaddr = round_page((vm_offset_t)addr + len); 145 rv = vm_map_check_protection(&kernel_map, saddr, eaddr, prot, FALSE); 146 147 return (rv == TRUE); 148 } 149 150 /* 151 * No requirements. 152 */ 153 int 154 useracc(c_caddr_t addr, int len, int rw) 155 { 156 boolean_t rv; 157 vm_prot_t prot; 158 vm_map_t map; 159 vm_map_entry_t save_hint; 160 vm_offset_t wrap; 161 vm_offset_t gpa; 162 163 KASSERT((rw & (~VM_PROT_ALL)) == 0, 164 ("illegal ``rw'' argument to useracc (%x)", rw)); 165 prot = rw; 166 167 if (curthread->td_vmm) { 168 if (vmm_vm_get_gpa(curproc, (register_t *)&gpa, (register_t) addr)) 169 panic("%s: could not get GPA\n", __func__); 170 addr = (c_caddr_t) gpa; 171 } 172 173 /* 174 * XXX - check separately to disallow access to user area and user 175 * page tables - they are in the map. 176 */ 177 wrap = (vm_offset_t)addr + len; 178 if (wrap > VM_MAX_USER_ADDRESS || wrap < (vm_offset_t)addr) { 179 return (FALSE); 180 } 181 map = &curproc->p_vmspace->vm_map; 182 vm_map_lock_read(map); 183 /* 184 * We save the map hint, and restore it. Useracc appears to distort 185 * the map hint unnecessarily. 186 */ 187 save_hint = map->hint; 188 rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr), 189 round_page(wrap), prot, TRUE); 190 map->hint = save_hint; 191 vm_map_unlock_read(map); 192 193 return (rv == TRUE); 194 } 195 196 /* 197 * No requirements. 198 */ 199 void 200 vslock(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), 0); 206 } 207 } 208 209 /* 210 * No requirements. 211 */ 212 void 213 vsunlock(caddr_t addr, u_int len) 214 { 215 if (len) { 216 vm_map_wire(&curproc->p_vmspace->vm_map, 217 trunc_page((vm_offset_t)addr), 218 round_page((vm_offset_t)addr + len), 219 KM_PAGEABLE); 220 } 221 } 222 223 /* 224 * Implement fork's actions on an address space. 225 * Here we arrange for the address space to be copied or referenced, 226 * allocate a user struct (pcb and kernel stack), then call the 227 * machine-dependent layer to fill those in and make the new process 228 * ready to run. The new process is set up so that it returns directly 229 * to user mode to avoid stack copying and relocation problems. 230 * 231 * No requirements. 232 */ 233 void 234 vm_fork(struct proc *p1, struct proc *p2, int flags) 235 { 236 if ((flags & RFPROC) == 0) { 237 /* 238 * Divorce the memory, if it is shared, essentially 239 * this changes shared memory amongst threads, into 240 * COW locally. 241 */ 242 if ((flags & RFMEM) == 0) { 243 if (vmspace_getrefs(p1->p_vmspace) > 1) { 244 vmspace_unshare(p1); 245 } 246 } 247 cpu_fork(ONLY_LWP_IN_PROC(p1), NULL, flags); 248 return; 249 } 250 251 if (flags & RFMEM) { 252 vmspace_ref(p1->p_vmspace); 253 p2->p_vmspace = p1->p_vmspace; 254 } 255 256 while (vm_page_count_severe()) { 257 vm_wait(0); 258 } 259 260 if ((flags & RFMEM) == 0) { 261 p2->p_vmspace = vmspace_fork(p1->p_vmspace); 262 263 pmap_pinit2(vmspace_pmap(p2->p_vmspace)); 264 265 if (p1->p_vmspace->vm_shm) 266 shmfork(p1, p2); 267 } 268 269 pmap_init_proc(p2); 270 } 271 272 /* 273 * Set default limits for VM system. Call during proc0's initialization. 274 * 275 * Called from the low level boot code only. 276 */ 277 void 278 vm_init_limits(struct proc *p) 279 { 280 int rss_limit; 281 282 /* 283 * Set up the initial limits on process VM. Set the maximum resident 284 * set size to be half of (reasonably) available memory. Since this 285 * is a soft limit, it comes into effect only when the system is out 286 * of memory - half of main memory helps to favor smaller processes, 287 * and reduces thrashing of the object cache. 288 */ 289 p->p_rlimit[RLIMIT_STACK].rlim_cur = dflssiz; 290 p->p_rlimit[RLIMIT_STACK].rlim_max = maxssiz; 291 p->p_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz; 292 p->p_rlimit[RLIMIT_DATA].rlim_max = maxdsiz; 293 /* limit the limit to no less than 2MB */ 294 rss_limit = max(vmstats.v_free_count, 512); 295 p->p_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit); 296 p->p_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY; 297 } 298 299 /* 300 * Faultin the specified process. Note that the process can be in any 301 * state. Just clear P_SWAPPEDOUT and call wakeup in case the process is 302 * sleeping. 303 * 304 * No requirements. 305 */ 306 void 307 faultin(struct proc *p) 308 { 309 if (p->p_flags & P_SWAPPEDOUT) { 310 /* 311 * The process is waiting in the kernel to return to user 312 * mode but cannot until P_SWAPPEDOUT gets cleared. 313 */ 314 lwkt_gettoken(&p->p_token); 315 p->p_flags &= ~(P_SWAPPEDOUT | P_SWAPWAIT); 316 #ifdef INVARIANTS 317 if (swap_debug) 318 kprintf("swapping in %d (%s)\n", p->p_pid, p->p_comm); 319 #endif 320 wakeup(p); 321 lwkt_reltoken(&p->p_token); 322 } 323 } 324 325 /* 326 * Kernel initialization eventually falls through to this function, 327 * which is process 0. 328 * 329 * This swapin algorithm attempts to swap-in processes only if there 330 * is enough space for them. Of course, if a process waits for a long 331 * time, it will be swapped in anyway. 332 */ 333 struct scheduler_info { 334 struct proc *pp; 335 int ppri; 336 }; 337 338 static int scheduler_callback(struct proc *p, void *data); 339 340 static void 341 scheduler(void *dummy) 342 { 343 struct scheduler_info info; 344 struct proc *p; 345 346 KKASSERT(!IN_CRITICAL_SECT(curthread)); 347 loop: 348 scheduler_notify = 0; 349 /* 350 * Don't try to swap anything in if we are low on memory. 351 */ 352 if (vm_page_count_severe()) { 353 vm_wait(0); 354 goto loop; 355 } 356 357 /* 358 * Look for a good candidate to wake up 359 */ 360 info.pp = NULL; 361 info.ppri = INT_MIN; 362 allproc_scan(scheduler_callback, &info); 363 364 /* 365 * Nothing to do, back to sleep for at least 1/10 of a second. If 366 * we are woken up, immediately process the next request. If 367 * multiple requests have built up the first is processed 368 * immediately and the rest are staggered. 369 */ 370 if ((p = info.pp) == NULL) { 371 tsleep(&proc0, 0, "nowork", hz / 10); 372 if (scheduler_notify == 0) 373 tsleep(&scheduler_notify, 0, "nowork", 0); 374 goto loop; 375 } 376 377 /* 378 * Fault the selected process in, then wait for a short period of 379 * time and loop up. 380 * 381 * XXX we need a heuristic to get a measure of system stress and 382 * then adjust our stagger wakeup delay accordingly. 383 */ 384 lwkt_gettoken(&p->p_token); 385 faultin(p); 386 p->p_swtime = 0; 387 lwkt_reltoken(&p->p_token); 388 PRELE(p); 389 tsleep(&proc0, 0, "swapin", hz / 10); 390 goto loop; 391 } 392 393 /* 394 * Process only has its hold count bumped, we need the token 395 * to safely scan the LWPs 396 */ 397 static int 398 scheduler_callback(struct proc *p, void *data) 399 { 400 struct scheduler_info *info = data; 401 struct vmspace *vm; 402 struct lwp *lp; 403 segsz_t pgs; 404 int pri; 405 406 /* 407 * We only care about processes in swap-wait. Interlock test with 408 * token if the flag is found set. 409 */ 410 if ((p->p_flags & P_SWAPWAIT) == 0) 411 return 0; 412 lwkt_gettoken_shared(&p->p_token); 413 if ((p->p_flags & P_SWAPWAIT) == 0) { 414 lwkt_reltoken(&p->p_token); 415 return 0; 416 } 417 418 /* 419 * Calculate priority for swap-in 420 */ 421 pri = 0; 422 FOREACH_LWP_IN_PROC(lp, p) { 423 /* XXX lwp might need a different metric */ 424 pri += lp->lwp_slptime; 425 } 426 pri += p->p_swtime - p->p_nice * 8; 427 428 /* 429 * The more pages paged out while we were swapped, 430 * the more work we have to do to get up and running 431 * again and the lower our wakeup priority. 432 * 433 * Each second of sleep time is worth ~1MB 434 */ 435 if ((vm = p->p_vmspace) != NULL) { 436 vmspace_hold(vm); 437 pgs = vmspace_resident_count(vm); 438 if (pgs < vm->vm_swrss) { 439 pri -= (vm->vm_swrss - pgs) / 440 (1024 * 1024 / PAGE_SIZE); 441 } 442 vmspace_drop(vm); 443 } 444 lwkt_reltoken(&p->p_token); 445 446 /* 447 * If this process is higher priority and there is 448 * enough space, then select this process instead of 449 * the previous selection. 450 */ 451 if (pri > info->ppri) { 452 if (info->pp) 453 PRELE(info->pp); 454 PHOLD(p); 455 info->pp = p; 456 info->ppri = pri; 457 } 458 return(0); 459 } 460 461 /* 462 * SMP races ok. 463 * No requirements. 464 */ 465 void 466 swapin_request(void) 467 { 468 if (scheduler_notify == 0) { 469 scheduler_notify = 1; 470 wakeup(&scheduler_notify); 471 } 472 } 473 474 #ifndef NO_SWAPPING 475 476 #define swappable(p) \ 477 (((p)->p_lock == 0) && \ 478 ((p)->p_flags & (P_TRACED|P_SYSTEM|P_SWAPPEDOUT|P_WEXIT)) == 0) 479 480 481 /* 482 * Swap_idle_threshold1 is the guaranteed swapped in time for a process 483 */ 484 static int swap_idle_threshold1 = 15; 485 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, 486 CTLFLAG_RW, &swap_idle_threshold1, 0, "Guaranteed process resident time (sec)"); 487 488 /* 489 * Swap_idle_threshold2 is the time that a process can be idle before 490 * it will be swapped out, if idle swapping is enabled. Default is 491 * one minute. 492 */ 493 static int swap_idle_threshold2 = 60; 494 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, 495 CTLFLAG_RW, &swap_idle_threshold2, 0, "Time (sec) a process can idle before being swapped"); 496 497 /* 498 * Swapout is driven by the pageout daemon. Very simple, we find eligible 499 * procs and mark them as being swapped out. This will cause the kernel 500 * to prefer to pageout those proc's pages first and the procs in question 501 * will not return to user mode until the swapper tells them they can. 502 * 503 * If any procs have been sleeping/stopped for at least maxslp seconds, 504 * they are swapped. Else, we swap the longest-sleeping or stopped process, 505 * if any, otherwise the longest-resident process. 506 */ 507 508 static int swapout_procs_callback(struct proc *p, void *data); 509 510 /* 511 * No requirements. 512 */ 513 void 514 swapout_procs(int action) 515 { 516 allproc_scan(swapout_procs_callback, &action); 517 } 518 519 static int 520 swapout_procs_callback(struct proc *p, void *data) 521 { 522 struct lwp *lp; 523 int action = *(int *)data; 524 int minslp = -1; 525 526 if (!swappable(p)) 527 return(0); 528 529 lwkt_gettoken(&p->p_token); 530 531 /* 532 * We only consider active processes. 533 */ 534 if (p->p_stat != SACTIVE && p->p_stat != SSTOP) { 535 lwkt_reltoken(&p->p_token); 536 return(0); 537 } 538 539 FOREACH_LWP_IN_PROC(lp, p) { 540 /* 541 * do not swap out a realtime process 542 */ 543 if (RTP_PRIO_IS_REALTIME(lp->lwp_rtprio.type)) { 544 lwkt_reltoken(&p->p_token); 545 return(0); 546 } 547 548 /* 549 * Guarentee swap_idle_threshold time in memory 550 */ 551 if (lp->lwp_slptime < swap_idle_threshold1) { 552 lwkt_reltoken(&p->p_token); 553 return(0); 554 } 555 556 /* 557 * If the system is under memory stress, or if we 558 * are swapping idle processes >= swap_idle_threshold2, 559 * then swap the process out. 560 */ 561 if (((action & VM_SWAP_NORMAL) == 0) && 562 (((action & VM_SWAP_IDLE) == 0) || 563 (lp->lwp_slptime < swap_idle_threshold2))) { 564 lwkt_reltoken(&p->p_token); 565 return(0); 566 } 567 568 if (minslp == -1 || lp->lwp_slptime < minslp) 569 minslp = lp->lwp_slptime; 570 } 571 572 /* 573 * If the process has been asleep for awhile, swap 574 * it out. 575 */ 576 if ((action & VM_SWAP_NORMAL) || 577 ((action & VM_SWAP_IDLE) && 578 (minslp > swap_idle_threshold2))) { 579 swapout(p); 580 } 581 582 /* 583 * cleanup our reference 584 */ 585 lwkt_reltoken(&p->p_token); 586 587 return(0); 588 } 589 590 /* 591 * The caller must hold p->p_token 592 */ 593 static void 594 swapout(struct proc *p) 595 { 596 #ifdef INVARIANTS 597 if (swap_debug) 598 kprintf("swapping out %d (%s)\n", p->p_pid, p->p_comm); 599 #endif 600 ++p->p_ru.ru_nswap; 601 602 /* 603 * remember the process resident count 604 */ 605 p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace); 606 p->p_flags |= P_SWAPPEDOUT; 607 p->p_swtime = 0; 608 } 609 610 #endif /* !NO_SWAPPING */ 611 612