2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * The Mach Operating System project at Carnegie-Mellon University.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * from: @(#)vm_glue.c 8.6 (Berkeley) 1/5/94
35 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
36 * All rights reserved.
38 * Permission to use, copy, modify and distribute this software and
39 * its documentation is hereby granted, provided that both the copyright
40 * notice and this permission notice appear in all copies of the
41 * software, derivative works or modified versions, and any portions
42 * thereof, and that both notices appear in supporting documentation.
44 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
45 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
46 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
48 * Carnegie Mellon requests users of this software to return to
50 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
51 * School of Computer Science
52 * Carnegie Mellon University
53 * Pittsburgh PA 15213-3890
55 * any improvements or extensions that they make and grant Carnegie the
56 * rights to redistribute these changes.
58 * $FreeBSD: src/sys/vm/vm_glue.c,v 1.94.2.4 2003/01/13 22:51:17 dillon Exp $
63 #include <sys/param.h>
64 #include <sys/systm.h>
66 #include <sys/resourcevar.h>
69 #include <sys/vmmeter.h>
70 #include <sys/sysctl.h>
72 #include <sys/kernel.h>
73 #include <sys/unistd.h>
75 #include <machine/limits.h>
76 #include <machine/vmm.h>
79 #include <vm/vm_param.h>
82 #include <vm/vm_map.h>
83 #include <vm/vm_page.h>
84 #include <vm/vm_pageout.h>
85 #include <vm/vm_kern.h>
86 #include <vm/vm_extern.h>
89 #include <vm/vm_page2.h>
90 #include <sys/thread2.h>
93 * THIS MUST BE THE LAST INITIALIZATION ITEM!!!
95 * Note: run scheduling should be divorced from the vm system.
97 static void scheduler (void *);
98 SYSINIT(scheduler
, SI_SUB_RUN_SCHEDULER
, SI_ORDER_FIRST
, scheduler
, NULL
);
102 static int swap_debug
= 0;
103 SYSCTL_INT(_vm
, OID_AUTO
, swap_debug
,
104 CTLFLAG_RW
, &swap_debug
, 0, "");
108 static int scheduler_notify
;
110 static void swapout (struct proc
*);
116 kernacc(c_caddr_t addr
, int len
, int rw
)
119 vm_offset_t saddr
, eaddr
;
122 KASSERT((rw
& (~VM_PROT_ALL
)) == 0,
123 ("illegal ``rw'' argument to kernacc (%x)", rw
));
126 * The globaldata space is not part of the kernel_map proper,
127 * check access separately.
129 if (is_globaldata_space((vm_offset_t
)addr
, (vm_offset_t
)(addr
+ len
)))
133 * Nominal kernel memory access - check access via kernel_map.
135 if ((vm_offset_t
)addr
+ len
> kernel_map
.max_offset
||
136 (vm_offset_t
)addr
+ len
< (vm_offset_t
)addr
) {
140 saddr
= trunc_page((vm_offset_t
)addr
);
141 eaddr
= round_page((vm_offset_t
)addr
+ len
);
142 rv
= vm_map_check_protection(&kernel_map
, saddr
, eaddr
, prot
, FALSE
);
151 useracc(c_caddr_t addr
, int len
, int rw
)
159 KASSERT((rw
& (~VM_PROT_ALL
)) == 0,
160 ("illegal ``rw'' argument to useracc (%x)", rw
));
163 if (curthread
->td_vmm
) {
164 if (vmm_vm_get_gpa(curproc
, (register_t
*)&gpa
, (register_t
) addr
))
165 panic("%s: could not get GPA\n", __func__
);
166 addr
= (c_caddr_t
) gpa
;
170 * XXX - check separately to disallow access to user area and user
171 * page tables - they are in the map.
173 wrap
= (vm_offset_t
)addr
+ len
;
174 if (wrap
> VM_MAX_USER_ADDRESS
|| wrap
< (vm_offset_t
)addr
) {
177 map
= &curproc
->p_vmspace
->vm_map
;
178 vm_map_lock_read(map
);
180 rv
= vm_map_check_protection(map
, trunc_page((vm_offset_t
)addr
),
181 round_page(wrap
), prot
, TRUE
);
182 vm_map_unlock_read(map
);
191 vslock(caddr_t addr
, u_int len
)
194 vm_map_wire(&curproc
->p_vmspace
->vm_map
,
195 trunc_page((vm_offset_t
)addr
),
196 round_page((vm_offset_t
)addr
+ len
), 0);
204 vsunlock(caddr_t addr
, u_int len
)
207 vm_map_wire(&curproc
->p_vmspace
->vm_map
,
208 trunc_page((vm_offset_t
)addr
),
209 round_page((vm_offset_t
)addr
+ len
),
215 * Implement fork's actions on an address space.
216 * Here we arrange for the address space to be copied or referenced,
217 * allocate a user struct (pcb and kernel stack), then call the
218 * machine-dependent layer to fill those in and make the new process
219 * ready to run. The new process is set up so that it returns directly
220 * to user mode to avoid stack copying and relocation problems.
225 vm_fork(struct proc
*p1
, struct proc
*p2
, int flags
)
227 if ((flags
& RFPROC
) == 0) {
229 * Divorce the memory, if it is shared, essentially
230 * this changes shared memory amongst threads, into
233 if ((flags
& RFMEM
) == 0) {
234 if (vmspace_getrefs(p1
->p_vmspace
) > 1) {
238 cpu_fork(ONLY_LWP_IN_PROC(p1
), NULL
, flags
);
243 vmspace_ref(p1
->p_vmspace
);
244 p2
->p_vmspace
= p1
->p_vmspace
;
247 while (vm_page_count_severe()) {
251 if ((flags
& RFMEM
) == 0) {
252 p2
->p_vmspace
= vmspace_fork(p1
->p_vmspace
);
254 pmap_pinit2(vmspace_pmap(p2
->p_vmspace
));
256 if (p1
->p_vmspace
->vm_shm
)
264 * Set default limits for VM system. Call during proc0's initialization.
266 * Called from the low level boot code only.
269 vm_init_limits(struct proc
*p
)
274 * Set up the initial limits on process VM. Set the maximum resident
275 * set size to be half of (reasonably) available memory. Since this
276 * is a soft limit, it comes into effect only when the system is out
277 * of memory - half of main memory helps to favor smaller processes,
278 * and reduces thrashing of the object cache.
280 p
->p_rlimit
[RLIMIT_STACK
].rlim_cur
= dflssiz
;
281 p
->p_rlimit
[RLIMIT_STACK
].rlim_max
= maxssiz
;
282 p
->p_rlimit
[RLIMIT_DATA
].rlim_cur
= dfldsiz
;
283 p
->p_rlimit
[RLIMIT_DATA
].rlim_max
= maxdsiz
;
284 /* limit the limit to no less than 2MB */
285 rss_limit
= max(vmstats
.v_free_count
, 512);
286 p
->p_rlimit
[RLIMIT_RSS
].rlim_cur
= ptoa(rss_limit
);
287 p
->p_rlimit
[RLIMIT_RSS
].rlim_max
= RLIM_INFINITY
;
291 * Faultin the specified process. Note that the process can be in any
292 * state. Just clear P_SWAPPEDOUT and call wakeup in case the process is
298 faultin(struct proc
*p
)
300 if (p
->p_flags
& P_SWAPPEDOUT
) {
302 * The process is waiting in the kernel to return to user
303 * mode but cannot until P_SWAPPEDOUT gets cleared.
305 lwkt_gettoken(&p
->p_token
);
306 p
->p_flags
&= ~(P_SWAPPEDOUT
| P_SWAPWAIT
);
309 kprintf("swapping in %d (%s)\n", p
->p_pid
, p
->p_comm
);
312 lwkt_reltoken(&p
->p_token
);
317 * Kernel initialization eventually falls through to this function,
318 * which is process 0.
320 * This swapin algorithm attempts to swap-in processes only if there
321 * is enough space for them. Of course, if a process waits for a long
322 * time, it will be swapped in anyway.
324 struct scheduler_info
{
329 static int scheduler_callback(struct proc
*p
, void *data
);
332 scheduler(void *dummy
)
334 struct scheduler_info info
;
337 KKASSERT(!IN_CRITICAL_SECT(curthread
));
339 scheduler_notify
= 0;
341 * Don't try to swap anything in if we are low on memory.
343 if (vm_page_count_severe()) {
349 * Look for a good candidate to wake up
351 * XXX we should make the schedule thread pcpu and then use a
352 * segmented allproc scan.
356 allproc_scan(scheduler_callback
, &info
, 0);
359 * Nothing to do, back to sleep for at least 1/10 of a second. If
360 * we are woken up, immediately process the next request. If
361 * multiple requests have built up the first is processed
362 * immediately and the rest are staggered.
364 if ((p
= info
.pp
) == NULL
) {
365 tsleep(&proc0
, 0, "nowork", hz
/ 10);
366 if (scheduler_notify
== 0)
367 tsleep(&scheduler_notify
, 0, "nowork", 0);
372 * Fault the selected process in, then wait for a short period of
375 * XXX we need a heuristic to get a measure of system stress and
376 * then adjust our stagger wakeup delay accordingly.
378 lwkt_gettoken(&p
->p_token
);
381 lwkt_reltoken(&p
->p_token
);
383 tsleep(&proc0
, 0, "swapin", hz
/ 10);
388 * Process only has its hold count bumped, we need the token
389 * to safely scan the LWPs
392 scheduler_callback(struct proc
*p
, void *data
)
394 struct scheduler_info
*info
= data
;
401 * We only care about processes in swap-wait. Interlock test with
402 * token if the flag is found set.
404 if ((p
->p_flags
& P_SWAPWAIT
) == 0)
406 lwkt_gettoken_shared(&p
->p_token
);
407 if ((p
->p_flags
& P_SWAPWAIT
) == 0) {
408 lwkt_reltoken(&p
->p_token
);
413 * Calculate priority for swap-in
416 FOREACH_LWP_IN_PROC(lp
, p
) {
417 /* XXX lwp might need a different metric */
418 pri
+= lp
->lwp_slptime
;
420 pri
+= p
->p_swtime
- p
->p_nice
* 8;
423 * The more pages paged out while we were swapped,
424 * the more work we have to do to get up and running
425 * again and the lower our wakeup priority.
427 * Each second of sleep time is worth ~1MB
429 if ((vm
= p
->p_vmspace
) != NULL
) {
431 pgs
= vmspace_resident_count(vm
);
432 if (pgs
< vm
->vm_swrss
) {
433 pri
-= (vm
->vm_swrss
- pgs
) /
434 (1024 * 1024 / PAGE_SIZE
);
438 lwkt_reltoken(&p
->p_token
);
441 * If this process is higher priority and there is
442 * enough space, then select this process instead of
443 * the previous selection.
445 if (pri
> info
->ppri
) {
462 if (scheduler_notify
== 0) {
463 scheduler_notify
= 1;
464 wakeup(&scheduler_notify
);
470 #define swappable(p) \
471 (((p)->p_lock == 0) && \
472 ((p)->p_flags & (P_TRACED|P_SYSTEM|P_SWAPPEDOUT|P_WEXIT)) == 0)
476 * Swap_idle_threshold1 is the guaranteed swapped in time for a process
478 static int swap_idle_threshold1
= 15;
479 SYSCTL_INT(_vm
, OID_AUTO
, swap_idle_threshold1
,
480 CTLFLAG_RW
, &swap_idle_threshold1
, 0, "Guaranteed process resident time (sec)");
483 * Swap_idle_threshold2 is the time that a process can be idle before
484 * it will be swapped out, if idle swapping is enabled. Default is
487 static int swap_idle_threshold2
= 60;
488 SYSCTL_INT(_vm
, OID_AUTO
, swap_idle_threshold2
,
489 CTLFLAG_RW
, &swap_idle_threshold2
, 0, "Time (sec) a process can idle before being swapped");
492 * Swapout is driven by the pageout daemon. Very simple, we find eligible
493 * procs and mark them as being swapped out. This will cause the kernel
494 * to prefer to pageout those proc's pages first and the procs in question
495 * will not return to user mode until the swapper tells them they can.
497 * If any procs have been sleeping/stopped for at least maxslp seconds,
498 * they are swapped. Else, we swap the longest-sleeping or stopped process,
499 * if any, otherwise the longest-resident process.
502 static int swapout_procs_callback(struct proc
*p
, void *data
);
508 swapout_procs(int action
)
510 allproc_scan(swapout_procs_callback
, &action
, 0);
514 swapout_procs_callback(struct proc
*p
, void *data
)
517 int action
= *(int *)data
;
523 lwkt_gettoken(&p
->p_token
);
526 * We only consider active processes.
528 if (p
->p_stat
!= SACTIVE
&& p
->p_stat
!= SSTOP
) {
529 lwkt_reltoken(&p
->p_token
);
533 FOREACH_LWP_IN_PROC(lp
, p
) {
535 * do not swap out a realtime process
537 if (RTP_PRIO_IS_REALTIME(lp
->lwp_rtprio
.type
)) {
538 lwkt_reltoken(&p
->p_token
);
543 * Guarentee swap_idle_threshold time in memory
545 if (lp
->lwp_slptime
< swap_idle_threshold1
) {
546 lwkt_reltoken(&p
->p_token
);
551 * If the system is under memory stress, or if we
552 * are swapping idle processes >= swap_idle_threshold2,
553 * then swap the process out.
555 if (((action
& VM_SWAP_NORMAL
) == 0) &&
556 (((action
& VM_SWAP_IDLE
) == 0) ||
557 (lp
->lwp_slptime
< swap_idle_threshold2
))) {
558 lwkt_reltoken(&p
->p_token
);
562 if (minslp
== -1 || lp
->lwp_slptime
< minslp
)
563 minslp
= lp
->lwp_slptime
;
567 * If the process has been asleep for awhile, swap
570 if ((action
& VM_SWAP_NORMAL
) ||
571 ((action
& VM_SWAP_IDLE
) &&
572 (minslp
> swap_idle_threshold2
))) {
577 * cleanup our reference
579 lwkt_reltoken(&p
->p_token
);
585 * The caller must hold p->p_token
588 swapout(struct proc
*p
)
592 kprintf("swapping out %d (%s)\n", p
->p_pid
, p
->p_comm
);
597 * remember the process resident count
599 p
->p_vmspace
->vm_swrss
= vmspace_resident_count(p
->p_vmspace
);
600 p
->p_flags
|= P_SWAPPEDOUT
;
604 #endif /* !NO_SWAPPING */