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freebsd-dev/sys/vm/vm_glue.c
Alan Cox d19ef81437 The synchronization provided by vm object locking has eliminated the 
need for most calls to vm_page_busy().  Specifically, most calls to
vm_page_busy() occur immediately prior to a call to vm_page_remove().
In such cases, the containing vm object is locked across both calls.
Consequently, the setting of the vm page's PG_BUSY flag is not even
visible to other threads that are following the synchronization
protocol.

This change (1) eliminates the calls to vm_page_busy() that
immediately precede a call to vm_page_remove() or functions, such as
vm_page_free() and vm_page_rename(), that call it and (2) relaxes the
requirement in vm_page_remove() that the vm page's PG_BUSY flag is
set.  Now, the vm page's PG_BUSY flag is set only when the vm object
lock is released while the vm page is still in transition.  Typically,
this is when it is undergoing I/O.
2004-11-03 20:17:31 +00:00

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/*
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* The Mach Operating System project at Carnegie-Mellon University.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)vm_glue.c 8.6 (Berkeley) 1/5/94
*
*
* Copyright (c) 1987, 1990 Carnegie-Mellon University.
* All rights reserved.
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_vm.h"
#include "opt_kstack_pages.h"
#include "opt_kstack_max_pages.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/shm.h>
#include <sys/vmmeter.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/unistd.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_object.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/vm_pager.h>
#include <vm/swap_pager.h>
#include <sys/user.h>
extern int maxslp;
/*
* System initialization
*
* Note: proc0 from proc.h
*/
static void vm_init_limits(void *);
SYSINIT(vm_limits, SI_SUB_VM_CONF, SI_ORDER_FIRST, vm_init_limits, &proc0)
/*
* THIS MUST BE THE LAST INITIALIZATION ITEM!!!
*
* Note: run scheduling should be divorced from the vm system.
*/
static void scheduler(void *);
SYSINIT(scheduler, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY, scheduler, NULL)
#ifndef NO_SWAPPING
static void swapout(struct proc *);
static void vm_proc_swapin(struct proc *p);
static void vm_proc_swapout(struct proc *p);
#endif
/*
* MPSAFE
*
* WARNING! This code calls vm_map_check_protection() which only checks
* the associated vm_map_entry range. It does not determine whether the
* contents of the memory is actually readable or writable. In most cases
* just checking the vm_map_entry is sufficient within the kernel's address
* space.
*/
int
kernacc(addr, len, rw)
void *addr;
int len, rw;
{
boolean_t rv;
vm_offset_t saddr, eaddr;
vm_prot_t prot;
KASSERT((rw & ~VM_PROT_ALL) == 0,
("illegal ``rw'' argument to kernacc (%x)\n", rw));
prot = rw;
saddr = trunc_page((vm_offset_t)addr);
eaddr = round_page((vm_offset_t)addr + len);
vm_map_lock_read(kernel_map);
rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot);
vm_map_unlock_read(kernel_map);
return (rv == TRUE);
}
/*
* MPSAFE
*
* WARNING! This code calls vm_map_check_protection() which only checks
* the associated vm_map_entry range. It does not determine whether the
* contents of the memory is actually readable or writable. vmapbuf(),
* vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be
* used in conjuction with this call.
*/
int
useracc(addr, len, rw)
void *addr;
int len, rw;
{
boolean_t rv;
vm_prot_t prot;
vm_map_t map;
KASSERT((rw & ~VM_PROT_ALL) == 0,
("illegal ``rw'' argument to useracc (%x)\n", rw));
prot = rw;
map = &curproc->p_vmspace->vm_map;
if ((vm_offset_t)addr + len > vm_map_max(map) ||
(vm_offset_t)addr + len < (vm_offset_t)addr) {
return (FALSE);
}
vm_map_lock_read(map);
rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr),
round_page((vm_offset_t)addr + len), prot);
vm_map_unlock_read(map);
return (rv == TRUE);
}
int
vslock(void *addr, size_t len)
{
vm_offset_t end, last, start;
vm_size_t npages;
int error;
last = (vm_offset_t)addr + len;
start = trunc_page((vm_offset_t)addr);
end = round_page(last);
if (last < (vm_offset_t)addr || end < (vm_offset_t)addr)
return (EINVAL);
npages = atop(end - start);
if (npages > vm_page_max_wired)
return (ENOMEM);
PROC_LOCK(curproc);
if (ptoa(npages +
pmap_wired_count(vm_map_pmap(&curproc->p_vmspace->vm_map))) >
lim_cur(curproc, RLIMIT_MEMLOCK)) {
PROC_UNLOCK(curproc);
return (ENOMEM);
}
PROC_UNLOCK(curproc);
#if 0
/*
* XXX - not yet
*
* The limit for transient usage of wired pages should be
* larger than for "permanent" wired pages (mlock()).
*
* Also, the sysctl code, which is the only present user
* of vslock(), does a hard loop on EAGAIN.
*/
if (npages + cnt.v_wire_count > vm_page_max_wired)
return (EAGAIN);
#endif
error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end,
VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
/*
* Return EFAULT on error to match copy{in,out}() behaviour
* rather than returning ENOMEM like mlock() would.
*/
return (error == KERN_SUCCESS ? 0 : EFAULT);
}
void
vsunlock(void *addr, size_t len)
{
/* Rely on the parameter sanity checks performed by vslock(). */
(void)vm_map_unwire(&curproc->p_vmspace->vm_map,
trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len),
VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
}
/*
* Create the U area for a new process.
* This routine directly affects the fork perf for a process.
*/
void
vm_proc_new(struct proc *p)
{
vm_page_t ma[UAREA_PAGES];
vm_object_t upobj;
vm_offset_t up;
vm_page_t m;
u_int i;
/*
* Get a kernel virtual address for the U area for this process.
*/
up = kmem_alloc_nofault(kernel_map, UAREA_PAGES * PAGE_SIZE);
if (up == 0)
panic("vm_proc_new: upage allocation failed");
p->p_uarea = (struct user *)up;
/*
* Allocate object and page(s) for the U area.
*/
upobj = vm_object_allocate(OBJT_DEFAULT, UAREA_PAGES);
p->p_upages_obj = upobj;
VM_OBJECT_LOCK(upobj);
for (i = 0; i < UAREA_PAGES; i++) {
m = vm_page_grab(upobj, i, VM_ALLOC_NOBUSY |
VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED);
ma[i] = m;
m->valid = VM_PAGE_BITS_ALL;
}
VM_OBJECT_UNLOCK(upobj);
/*
* Enter the pages into the kernel address space.
*/
pmap_qenter(up, ma, UAREA_PAGES);
}
/*
* Dispose the U area for a process that has exited.
* This routine directly impacts the exit perf of a process.
*
* XXX UNUSED
* U areas of free proc structures are no longer freed and are never
* swapped out. Ideally we would free U areas lazily, when low on memory.
*/
void
vm_proc_dispose(struct proc *p)
{
vm_object_t upobj;
vm_offset_t up;
vm_page_t m;
upobj = p->p_upages_obj;
VM_OBJECT_LOCK(upobj);
if (upobj->resident_page_count != UAREA_PAGES)
panic("vm_proc_dispose: incorrect number of pages in upobj");
vm_page_lock_queues();
while ((m = TAILQ_FIRST(&upobj->memq)) != NULL) {
vm_page_unwire(m, 0);
vm_page_free(m);
}
vm_page_unlock_queues();
VM_OBJECT_UNLOCK(upobj);
up = (vm_offset_t)p->p_uarea;
pmap_qremove(up, UAREA_PAGES);
kmem_free(kernel_map, up, UAREA_PAGES * PAGE_SIZE);
vm_object_deallocate(upobj);
}
#ifndef NO_SWAPPING
/*
* Allow the U area for a process to be prejudicially paged out.
*/
static void
vm_proc_swapout(struct proc *p)
{
vm_object_t upobj;
vm_offset_t up;
vm_page_t m;
upobj = p->p_upages_obj;
VM_OBJECT_LOCK(upobj);
if (upobj->resident_page_count != UAREA_PAGES)
panic("vm_proc_dispose: incorrect number of pages in upobj");
vm_page_lock_queues();
TAILQ_FOREACH(m, &upobj->memq, listq) {
vm_page_dirty(m);
vm_page_unwire(m, 0);
}
vm_page_unlock_queues();
VM_OBJECT_UNLOCK(upobj);
up = (vm_offset_t)p->p_uarea;
pmap_qremove(up, UAREA_PAGES);
}
/*
* Bring the U area for a specified process back in.
*/
static void
vm_proc_swapin(struct proc *p)
{
vm_page_t ma[UAREA_PAGES];
vm_object_t upobj;
vm_offset_t up;
vm_page_t m;
int rv;
int i;
upobj = p->p_upages_obj;
VM_OBJECT_LOCK(upobj);
for (i = 0; i < UAREA_PAGES; i++) {
m = vm_page_grab(upobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
if (m->valid != VM_PAGE_BITS_ALL) {
rv = vm_pager_get_pages(upobj, &m, 1, 0);
if (rv != VM_PAGER_OK)
panic("vm_proc_swapin: cannot get upage");
}
ma[i] = m;
}
if (upobj->resident_page_count != UAREA_PAGES)
panic("vm_proc_swapin: lost pages from upobj");
vm_page_lock_queues();
TAILQ_FOREACH(m, &upobj->memq, listq) {
m->valid = VM_PAGE_BITS_ALL;
vm_page_wire(m);
vm_page_wakeup(m);
}
vm_page_unlock_queues();
VM_OBJECT_UNLOCK(upobj);
up = (vm_offset_t)p->p_uarea;
pmap_qenter(up, ma, UAREA_PAGES);
}
/*
* Swap in the UAREAs of all processes swapped out to the given device.
* The pages in the UAREA are marked dirty and their swap metadata is freed.
*/
void
vm_proc_swapin_all(struct swdevt *devidx)
{
struct proc *p;
vm_object_t object;
vm_page_t m;
retry:
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
PROC_LOCK(p);
object = p->p_upages_obj;
if (object != NULL) {
VM_OBJECT_LOCK(object);
if (swap_pager_isswapped(object, devidx)) {
VM_OBJECT_UNLOCK(object);
sx_sunlock(&allproc_lock);
faultin(p);
PROC_UNLOCK(p);
VM_OBJECT_LOCK(object);
vm_page_lock_queues();
TAILQ_FOREACH(m, &object->memq, listq)
vm_page_dirty(m);
vm_page_unlock_queues();
swap_pager_freespace(object, 0,
object->un_pager.swp.swp_bcount);
VM_OBJECT_UNLOCK(object);
goto retry;
}
VM_OBJECT_UNLOCK(object);
}
PROC_UNLOCK(p);
}
sx_sunlock(&allproc_lock);
}
#endif
#ifndef KSTACK_MAX_PAGES
#define KSTACK_MAX_PAGES 32
#endif
/*
* Create the kernel stack (including pcb for i386) for a new thread.
* This routine directly affects the fork perf for a process and
* create performance for a thread.
*/
void
vm_thread_new(struct thread *td, int pages)
{
vm_object_t ksobj;
vm_offset_t ks;
vm_page_t m, ma[KSTACK_MAX_PAGES];
int i;
/* Bounds check */
if (pages <= 1)
pages = KSTACK_PAGES;
else if (pages > KSTACK_MAX_PAGES)
pages = KSTACK_MAX_PAGES;
/*
* Allocate an object for the kstack.
*/
ksobj = vm_object_allocate(OBJT_DEFAULT, pages);
td->td_kstack_obj = ksobj;
/*
* Get a kernel virtual address for this thread's kstack.
*/
ks = kmem_alloc_nofault(kernel_map,
(pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
if (ks == 0)
panic("vm_thread_new: kstack allocation failed");
if (KSTACK_GUARD_PAGES != 0) {
pmap_qremove(ks, KSTACK_GUARD_PAGES);
ks += KSTACK_GUARD_PAGES * PAGE_SIZE;
}
td->td_kstack = ks;
/*
* Knowing the number of pages allocated is useful when you
* want to deallocate them.
*/
td->td_kstack_pages = pages;
/*
* For the length of the stack, link in a real page of ram for each
* page of stack.
*/
VM_OBJECT_LOCK(ksobj);
for (i = 0; i < pages; i++) {
/*
* Get a kernel stack page.
*/
m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY |
VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED);
ma[i] = m;
m->valid = VM_PAGE_BITS_ALL;
}
VM_OBJECT_UNLOCK(ksobj);
pmap_qenter(ks, ma, pages);
}
/*
* Dispose of a thread's kernel stack.
*/
void
vm_thread_dispose(struct thread *td)
{
vm_object_t ksobj;
vm_offset_t ks;
vm_page_t m;
int i, pages;
pages = td->td_kstack_pages;
ksobj = td->td_kstack_obj;
ks = td->td_kstack;
pmap_qremove(ks, pages);
VM_OBJECT_LOCK(ksobj);
for (i = 0; i < pages; i++) {
m = vm_page_lookup(ksobj, i);
if (m == NULL)
panic("vm_thread_dispose: kstack already missing?");
vm_page_lock_queues();
vm_page_unwire(m, 0);
vm_page_free(m);
vm_page_unlock_queues();
}
VM_OBJECT_UNLOCK(ksobj);
vm_object_deallocate(ksobj);
kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
(pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
}
/*
* Allow a thread's kernel stack to be paged out.
*/
void
vm_thread_swapout(struct thread *td)
{
vm_object_t ksobj;
vm_page_t m;
int i, pages;
cpu_thread_swapout(td);
pages = td->td_kstack_pages;
ksobj = td->td_kstack_obj;
pmap_qremove(td->td_kstack, pages);
VM_OBJECT_LOCK(ksobj);
for (i = 0; i < pages; i++) {
m = vm_page_lookup(ksobj, i);
if (m == NULL)
panic("vm_thread_swapout: kstack already missing?");
vm_page_lock_queues();
vm_page_dirty(m);
vm_page_unwire(m, 0);
vm_page_unlock_queues();
}
VM_OBJECT_UNLOCK(ksobj);
}
/*
* Bring the kernel stack for a specified thread back in.
*/
void
vm_thread_swapin(struct thread *td)
{
vm_object_t ksobj;
vm_page_t m, ma[KSTACK_MAX_PAGES];
int i, pages, rv;
pages = td->td_kstack_pages;
ksobj = td->td_kstack_obj;
VM_OBJECT_LOCK(ksobj);
for (i = 0; i < pages; i++) {
m = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
if (m->valid != VM_PAGE_BITS_ALL) {
rv = vm_pager_get_pages(ksobj, &m, 1, 0);
if (rv != VM_PAGER_OK)
panic("vm_thread_swapin: cannot get kstack for proc: %d", td->td_proc->p_pid);
m = vm_page_lookup(ksobj, i);
m->valid = VM_PAGE_BITS_ALL;
}
ma[i] = m;
vm_page_lock_queues();
vm_page_wire(m);
vm_page_wakeup(m);
vm_page_unlock_queues();
}
VM_OBJECT_UNLOCK(ksobj);
pmap_qenter(td->td_kstack, ma, pages);
cpu_thread_swapin(td);
}
/*
* Set up a variable-sized alternate kstack.
*/
void
vm_thread_new_altkstack(struct thread *td, int pages)
{
td->td_altkstack = td->td_kstack;
td->td_altkstack_obj = td->td_kstack_obj;
td->td_altkstack_pages = td->td_kstack_pages;
vm_thread_new(td, pages);
}
/*
* Restore the original kstack.
*/
void
vm_thread_dispose_altkstack(struct thread *td)
{
vm_thread_dispose(td);
td->td_kstack = td->td_altkstack;
td->td_kstack_obj = td->td_altkstack_obj;
td->td_kstack_pages = td->td_altkstack_pages;
td->td_altkstack = 0;
td->td_altkstack_obj = NULL;
td->td_altkstack_pages = 0;
}
/*
* Implement fork's actions on an address space.
* Here we arrange for the address space to be copied or referenced,
* allocate a user struct (pcb and kernel stack), then call the
* machine-dependent layer to fill those in and make the new process
* ready to run. The new process is set up so that it returns directly
* to user mode to avoid stack copying and relocation problems.
*/
void
vm_forkproc(td, p2, td2, flags)
struct thread *td;
struct proc *p2;
struct thread *td2;
int flags;
{
struct proc *p1 = td->td_proc;
if ((flags & RFPROC) == 0) {
/*
* Divorce the memory, if it is shared, essentially
* this changes shared memory amongst threads, into
* COW locally.
*/
if ((flags & RFMEM) == 0) {
if (p1->p_vmspace->vm_refcnt > 1) {
vmspace_unshare(p1);
}
}
cpu_fork(td, p2, td2, flags);
return;
}
if (flags & RFMEM) {
p2->p_vmspace = p1->p_vmspace;
atomic_add_int(&p1->p_vmspace->vm_refcnt, 1);
}
while (vm_page_count_severe()) {
VM_WAIT;
}
if ((flags & RFMEM) == 0) {
p2->p_vmspace = vmspace_fork(p1->p_vmspace);
if (p1->p_vmspace->vm_shm)
shmfork(p1, p2);
}
/*
* p_stats currently points at fields in the user struct.
* Copy parts of p_stats; zero the rest of p_stats (statistics).
*/
#define RANGEOF(type, start, end) (offsetof(type, end) - offsetof(type, start))
p2->p_stats = &p2->p_uarea->u_stats;
bzero(&p2->p_stats->pstat_startzero,
(unsigned) RANGEOF(struct pstats, pstat_startzero, pstat_endzero));
bcopy(&p1->p_stats->pstat_startcopy, &p2->p_stats->pstat_startcopy,
(unsigned) RANGEOF(struct pstats, pstat_startcopy, pstat_endcopy));
#undef RANGEOF
/*
* cpu_fork will copy and update the pcb, set up the kernel stack,
* and make the child ready to run.
*/
cpu_fork(td, p2, td2, flags);
}
/*
* Called after process has been wait(2)'ed apon and is being reaped.
* The idea is to reclaim resources that we could not reclaim while
* the process was still executing.
*/
void
vm_waitproc(p)
struct proc *p;
{
vmspace_exitfree(p); /* and clean-out the vmspace */
}
/*
* Set default limits for VM system.
* Called for proc 0, and then inherited by all others.
*
* XXX should probably act directly on proc0.
*/
static void
vm_init_limits(udata)
void *udata;
{
struct proc *p = udata;
struct plimit *limp;
int rss_limit;
/*
* Set up the initial limits on process VM. Set the maximum resident
* set size to be half of (reasonably) available memory. Since this
* is a soft limit, it comes into effect only when the system is out
* of memory - half of main memory helps to favor smaller processes,
* and reduces thrashing of the object cache.
*/
limp = p->p_limit;
limp->pl_rlimit[RLIMIT_STACK].rlim_cur = dflssiz;
limp->pl_rlimit[RLIMIT_STACK].rlim_max = maxssiz;
limp->pl_rlimit[RLIMIT_DATA].rlim_cur = dfldsiz;
limp->pl_rlimit[RLIMIT_DATA].rlim_max = maxdsiz;
/* limit the limit to no less than 2MB */
rss_limit = max(cnt.v_free_count, 512);
limp->pl_rlimit[RLIMIT_RSS].rlim_cur = ptoa(rss_limit);
limp->pl_rlimit[RLIMIT_RSS].rlim_max = RLIM_INFINITY;
}
void
faultin(p)
struct proc *p;
{
#ifdef NO_SWAPPING
PROC_LOCK_ASSERT(p, MA_OWNED);
if ((p->p_sflag & PS_INMEM) == 0)
panic("faultin: proc swapped out with NO_SWAPPING!");
#else /* !NO_SWAPPING */
struct thread *td;
GIANT_REQUIRED;
PROC_LOCK_ASSERT(p, MA_OWNED);
/*
* If another process is swapping in this process,
* just wait until it finishes.
*/
if (p->p_sflag & PS_SWAPPINGIN)
msleep(&p->p_sflag, &p->p_mtx, PVM, "faultin", 0);
else if ((p->p_sflag & PS_INMEM) == 0) {
/*
* Don't let another thread swap process p out while we are
* busy swapping it in.
*/
++p->p_lock;
mtx_lock_spin(&sched_lock);
p->p_sflag |= PS_SWAPPINGIN;
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
vm_proc_swapin(p);
FOREACH_THREAD_IN_PROC(p, td)
vm_thread_swapin(td);
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
p->p_sflag &= ~PS_SWAPPINGIN;
p->p_sflag |= PS_INMEM;
FOREACH_THREAD_IN_PROC(p, td) {
TD_CLR_SWAPPED(td);
if (TD_CAN_RUN(td))
setrunnable(td);
}
mtx_unlock_spin(&sched_lock);
wakeup(&p->p_sflag);
/* Allow other threads to swap p out now. */
--p->p_lock;
}
#endif /* NO_SWAPPING */
}
/*
* This swapin algorithm attempts to swap-in processes only if there
* is enough space for them. Of course, if a process waits for a long
* time, it will be swapped in anyway.
*
* XXXKSE - process with the thread with highest priority counts..
*
* Giant is still held at this point, to be released in tsleep.
*/
/* ARGSUSED*/
static void
scheduler(dummy)
void *dummy;
{
struct proc *p;
struct thread *td;
int pri;
struct proc *pp;
int ppri;
mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED);
/* GIANT_REQUIRED */
loop:
if (vm_page_count_min()) {
VM_WAIT;
goto loop;
}
pp = NULL;
ppri = INT_MIN;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
struct ksegrp *kg;
if (p->p_sflag & (PS_INMEM | PS_SWAPPINGOUT | PS_SWAPPINGIN)) {
continue;
}
mtx_lock_spin(&sched_lock);
FOREACH_THREAD_IN_PROC(p, td) {
/*
* An otherwise runnable thread of a process
* swapped out has only the TDI_SWAPPED bit set.
*
*/
if (td->td_inhibitors == TDI_SWAPPED) {
kg = td->td_ksegrp;
pri = p->p_swtime + kg->kg_slptime;
if ((p->p_sflag & PS_SWAPINREQ) == 0) {
pri -= p->p_nice * 8;
}
/*
* if this ksegrp is higher priority
* and there is enough space, then select
* this process instead of the previous
* selection.
*/
if (pri > ppri) {
pp = p;
ppri = pri;
}
}
}
mtx_unlock_spin(&sched_lock);
}
sx_sunlock(&allproc_lock);
/*
* Nothing to do, back to sleep.
*/
if ((p = pp) == NULL) {
tsleep(&proc0, PVM, "sched", maxslp * hz / 2);
goto loop;
}
PROC_LOCK(p);
/*
* Another process may be bringing or may have already
* brought this process in while we traverse all threads.
* Or, this process may even be being swapped out again.
*/
if (p->p_sflag & (PS_INMEM | PS_SWAPPINGOUT | PS_SWAPPINGIN)) {
PROC_UNLOCK(p);
goto loop;
}
mtx_lock_spin(&sched_lock);
p->p_sflag &= ~PS_SWAPINREQ;
mtx_unlock_spin(&sched_lock);
/*
* We would like to bring someone in. (only if there is space).
* [What checks the space? ]
*/
faultin(p);
PROC_UNLOCK(p);
mtx_lock_spin(&sched_lock);
p->p_swtime = 0;
mtx_unlock_spin(&sched_lock);
goto loop;
}
#ifndef NO_SWAPPING
/*
* Swap_idle_threshold1 is the guaranteed swapped in time for a process
*/
static int swap_idle_threshold1 = 2;
SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW,
&swap_idle_threshold1, 0, "Guaranteed swapped in time for a process");
/*
* Swap_idle_threshold2 is the time that a process can be idle before
* it will be swapped out, if idle swapping is enabled.
*/
static int swap_idle_threshold2 = 10;
SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW,
&swap_idle_threshold2, 0, "Time before a process will be swapped out");
/*
* Swapout is driven by the pageout daemon. Very simple, we find eligible
* procs and unwire their u-areas. We try to always "swap" at least one
* process in case we need the room for a swapin.
* If any procs have been sleeping/stopped for at least maxslp seconds,
* they are swapped. Else, we swap the longest-sleeping or stopped process,
* if any, otherwise the longest-resident process.
*/
void
swapout_procs(action)
int action;
{
struct proc *p;
struct thread *td;
struct ksegrp *kg;
int didswap = 0;
GIANT_REQUIRED;
retry:
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
struct vmspace *vm;
int minslptime = 100000;
/*
* Watch out for a process in
* creation. It may have no
* address space or lock yet.
*/
mtx_lock_spin(&sched_lock);
if (p->p_state == PRS_NEW) {
mtx_unlock_spin(&sched_lock);
continue;
}
mtx_unlock_spin(&sched_lock);
/*
* An aio daemon switches its
* address space while running.
* Perform a quick check whether
* a process has P_SYSTEM.
*/
if ((p->p_flag & P_SYSTEM) != 0)
continue;
/*
* Do not swapout a process that
* is waiting for VM data
* structures as there is a possible
* deadlock. Test this first as
* this may block.
*
* Lock the map until swapout
* finishes, or a thread of this
* process may attempt to alter
* the map.
*/
PROC_LOCK(p);
vm = p->p_vmspace;
KASSERT(vm != NULL,
("swapout_procs: a process has no address space"));
atomic_add_int(&vm->vm_refcnt, 1);
PROC_UNLOCK(p);
if (!vm_map_trylock(&vm->vm_map))
goto nextproc1;
PROC_LOCK(p);
if (p->p_lock != 0 ||
(p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT)
) != 0) {
goto nextproc2;
}
/*
* only aiod changes vmspace, however it will be
* skipped because of the if statement above checking
* for P_SYSTEM
*/
if ((p->p_sflag & (PS_INMEM|PS_SWAPPINGOUT|PS_SWAPPINGIN)) != PS_INMEM)
goto nextproc2;
switch (p->p_state) {
default:
/* Don't swap out processes in any sort
* of 'special' state. */
break;
case PRS_NORMAL:
mtx_lock_spin(&sched_lock);
/*
* do not swapout a realtime process
* Check all the thread groups..
*/
FOREACH_KSEGRP_IN_PROC(p, kg) {
if (PRI_IS_REALTIME(kg->kg_pri_class))
goto nextproc;
/*
* Guarantee swap_idle_threshold1
* time in memory.
*/
if (kg->kg_slptime < swap_idle_threshold1)
goto nextproc;
/*
* Do not swapout a process if it is
* waiting on a critical event of some
* kind or there is a thread whose
* pageable memory may be accessed.
*
* This could be refined to support
* swapping out a thread.
*/
FOREACH_THREAD_IN_GROUP(kg, td) {
if ((td->td_priority) < PSOCK ||
!thread_safetoswapout(td))
goto nextproc;
}
/*
* If the system is under memory stress,
* or if we are swapping
* idle processes >= swap_idle_threshold2,
* then swap the process out.
*/
if (((action & VM_SWAP_NORMAL) == 0) &&
(((action & VM_SWAP_IDLE) == 0) ||
(kg->kg_slptime < swap_idle_threshold2)))
goto nextproc;
if (minslptime > kg->kg_slptime)
minslptime = kg->kg_slptime;
}
/*
* If the pageout daemon didn't free enough pages,
* or if this process is idle and the system is
* configured to swap proactively, swap it out.
*/
if ((action & VM_SWAP_NORMAL) ||
((action & VM_SWAP_IDLE) &&
(minslptime > swap_idle_threshold2))) {
swapout(p);
didswap++;
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
vm_map_unlock(&vm->vm_map);
vmspace_free(vm);
sx_sunlock(&allproc_lock);
goto retry;
}
nextproc:
mtx_unlock_spin(&sched_lock);
}
nextproc2:
PROC_UNLOCK(p);
vm_map_unlock(&vm->vm_map);
nextproc1:
vmspace_free(vm);
continue;
}
sx_sunlock(&allproc_lock);
/*
* If we swapped something out, and another process needed memory,
* then wakeup the sched process.
*/
if (didswap)
wakeup(&proc0);
}
static void
swapout(p)
struct proc *p;
{
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED);
#if defined(SWAP_DEBUG)
printf("swapping out %d\n", p->p_pid);
#endif
/*
* The states of this process and its threads may have changed
* by now. Assuming that there is only one pageout daemon thread,
* this process should still be in memory.
*/
KASSERT((p->p_sflag & (PS_INMEM|PS_SWAPPINGOUT|PS_SWAPPINGIN)) == PS_INMEM,
("swapout: lost a swapout race?"));
#if defined(INVARIANTS)
/*
* Make sure that all threads are safe to be swapped out.
*
* Alternatively, we could swap out only safe threads.
*/
FOREACH_THREAD_IN_PROC(p, td) {
KASSERT(thread_safetoswapout(td),
("swapout: there is a thread not safe for swapout"));
}
#endif /* INVARIANTS */
++p->p_stats->p_ru.ru_nswap;
/*
* remember the process resident count
*/
p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
p->p_sflag &= ~PS_INMEM;
p->p_sflag |= PS_SWAPPINGOUT;
PROC_UNLOCK(p);
FOREACH_THREAD_IN_PROC(p, td)
TD_SET_SWAPPED(td);
mtx_unlock_spin(&sched_lock);
vm_proc_swapout(p);
FOREACH_THREAD_IN_PROC(p, td)
vm_thread_swapout(td);
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
p->p_sflag &= ~PS_SWAPPINGOUT;
p->p_swtime = 0;
}
#endif /* !NO_SWAPPING */
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