freebsd-dev/sys/vm/vm_glue.c
Jeff Roberson 8df78c41d6 - Make SCHED_STATS more generic by adding a wrapper to create the
variables and sysctl nodes.
 - In reset walk the children of kern_sched_stats and reset the counters
   via the oid_arg1 pointer.  This allows us to add arbitrary counters to
   the tree and still reset them properly.
 - Define a set of switch types to be passed with flags to mi_switch().
   These types are named SWT_*.  These types correspond to SCHED_STATS
   counters and are automatically handled in this way.
 - Make the new SWT_ types more specific than the older switch stats.
   There are now stats for idle switches, remote idle wakeups, remote
   preemption ithreads idling, etc.
 - Add switch statistics for ULE's pickcpu algorithm.  These stats include
   how much migration there is, how often affinity was successful, how
   often threads were migrated to the local cpu on wakeup, etc.

Sponsored by:	Nokia
2008-04-17 04:20:10 +00:00

1047 lines
25 KiB
C

/*-
* 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/sched.h>
#include <sys/sf_buf.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>
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 int swapout(struct proc *);
static void swapclear(struct proc *);
#endif
static volatile int proc0_rescan;
/*
* 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));
if ((vm_offset_t)addr + len > kernel_map->max_offset ||
(vm_offset_t)addr + len < (vm_offset_t)addr)
return (FALSE);
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);
}
/*
* Pin the page contained within the given object at the given offset. If the
* page is not resident, allocate and load it using the given object's pager.
* Return the pinned page if successful; otherwise, return NULL.
*/
static vm_page_t
vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset)
{
vm_page_t m, ma[1];
vm_pindex_t pindex;
int rv;
VM_OBJECT_LOCK(object);
pindex = OFF_TO_IDX(offset);
m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) {
ma[0] = m;
rv = vm_pager_get_pages(object, ma, 1, 0);
m = vm_page_lookup(object, pindex);
if (m == NULL)
goto out;
if (m->valid == 0 || rv != VM_PAGER_OK) {
vm_page_lock_queues();
vm_page_free(m);
vm_page_unlock_queues();
m = NULL;
goto out;
}
}
vm_page_lock_queues();
vm_page_hold(m);
vm_page_unlock_queues();
vm_page_wakeup(m);
out:
VM_OBJECT_UNLOCK(object);
return (m);
}
/*
* Return a CPU private mapping to the page at the given offset within the
* given object. The page is pinned before it is mapped.
*/
struct sf_buf *
vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset)
{
vm_page_t m;
m = vm_imgact_hold_page(object, offset);
if (m == NULL)
return (NULL);
sched_pin();
return (sf_buf_alloc(m, SFB_CPUPRIVATE));
}
/*
* Destroy the given CPU private mapping and unpin the page that it mapped.
*/
void
vm_imgact_unmap_page(struct sf_buf *sf)
{
vm_page_t m;
m = sf_buf_page(sf);
sf_buf_free(sf);
sched_unpin();
vm_page_lock_queues();
vm_page_unhold(m);
vm_page_unlock_queues();
}
#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.
*/
int
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);
/*
* 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) {
printf("vm_thread_new: kstack allocation failed\n");
vm_object_deallocate(ksobj);
return (0);
}
if (KSTACK_GUARD_PAGES != 0) {
pmap_qremove(ks, KSTACK_GUARD_PAGES);
ks += KSTACK_GUARD_PAGES * PAGE_SIZE;
}
td->td_kstack_obj = ksobj;
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);
return (1);
}
/*
* 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);
td->td_kstack = 0;
}
/*
* 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_unlock_queues();
vm_page_wakeup(m);
}
VM_OBJECT_UNLOCK(ksobj);
pmap_qenter(td->td_kstack, ma, pages);
cpu_thread_swapin(td);
}
/*
* Set up a variable-sized alternate kstack.
*/
int
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;
return (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.
*/
int
vm_forkproc(td, p2, td2, vm2, flags)
struct thread *td;
struct proc *p2;
struct thread *td2;
struct vmspace *vm2;
int flags;
{
struct proc *p1 = td->td_proc;
int error;
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) {
error = vmspace_unshare(p1);
if (error)
return (error);
}
}
cpu_fork(td, p2, td2, flags);
return (0);
}
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 = vm2;
if (p1->p_vmspace->vm_shm)
shmfork(p1, p2);
}
/*
* 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);
return (0);
}
/*
* 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_flag & P_INMEM) == 0)
panic("faultin: proc swapped out with NO_SWAPPING!");
#else /* !NO_SWAPPING */
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
/*
* If another process is swapping in this process,
* just wait until it finishes.
*/
if (p->p_flag & P_SWAPPINGIN) {
while (p->p_flag & P_SWAPPINGIN)
msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0);
return;
}
if ((p->p_flag & P_INMEM) == 0) {
/*
* Don't let another thread swap process p out while we are
* busy swapping it in.
*/
++p->p_lock;
p->p_flag |= P_SWAPPINGIN;
PROC_UNLOCK(p);
/*
* We hold no lock here because the list of threads
* can not change while all threads in the process are
* swapped out.
*/
FOREACH_THREAD_IN_PROC(p, td)
vm_thread_swapin(td);
PROC_LOCK(p);
swapclear(p);
p->p_swtick = ticks;
wakeup(&p->p_flag);
/* 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.
*
* Giant is held on entry.
*/
/* ARGSUSED*/
static void
scheduler(dummy)
void *dummy;
{
struct proc *p;
struct thread *td;
struct proc *pp;
int slptime;
int swtime;
int ppri;
int pri;
mtx_assert(&Giant, MA_OWNED | MA_NOTRECURSED);
mtx_unlock(&Giant);
loop:
if (vm_page_count_min()) {
VM_WAIT;
thread_lock(&thread0);
proc0_rescan = 0;
thread_unlock(&thread0);
goto loop;
}
pp = NULL;
ppri = INT_MIN;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
PROC_LOCK(p);
if (p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) {
PROC_UNLOCK(p);
continue;
}
swtime = (ticks - p->p_swtick) / hz;
FOREACH_THREAD_IN_PROC(p, td) {
/*
* An otherwise runnable thread of a process
* swapped out has only the TDI_SWAPPED bit set.
*
*/
thread_lock(td);
if (td->td_inhibitors == TDI_SWAPPED) {
slptime = (ticks - td->td_slptick) / hz;
pri = swtime + slptime;
if ((td->td_flags & TDF_SWAPINREQ) == 0)
pri -= p->p_nice * 8;
/*
* if this thread is higher priority
* and there is enough space, then select
* this process instead of the previous
* selection.
*/
if (pri > ppri) {
pp = p;
ppri = pri;
}
}
thread_unlock(td);
}
PROC_UNLOCK(p);
}
sx_sunlock(&allproc_lock);
/*
* Nothing to do, back to sleep.
*/
if ((p = pp) == NULL) {
thread_lock(&thread0);
if (!proc0_rescan) {
TD_SET_IWAIT(&thread0);
mi_switch(SW_VOL | SWT_IWAIT, NULL);
}
proc0_rescan = 0;
thread_unlock(&thread0);
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_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) {
PROC_UNLOCK(p);
thread_lock(&thread0);
proc0_rescan = 0;
thread_unlock(&thread0);
goto loop;
}
/*
* We would like to bring someone in. (only if there is space).
* [What checks the space? ]
*/
faultin(p);
PROC_UNLOCK(p);
thread_lock(&thread0);
proc0_rescan = 0;
thread_unlock(&thread0);
goto loop;
}
void kick_proc0(void)
{
struct thread *td = &thread0;
/* XXX This will probably cause a LOR in some cases */
thread_lock(td);
if (TD_AWAITING_INTR(td)) {
CTR2(KTR_INTR, "%s: sched_add %d", __func__, 0);
TD_CLR_IWAIT(td);
sched_add(td, SRQ_INTR);
} else {
proc0_rescan = 1;
CTR2(KTR_INTR, "%s: state %d",
__func__, td->td_state);
}
thread_unlock(td);
}
#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 swap out their stacks. 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;
int didswap = 0;
retry:
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
struct vmspace *vm;
int minslptime = 100000;
int slptime;
/*
* Watch out for a process in
* creation. It may have no
* address space or lock yet.
*/
if (p->p_state == PRS_NEW)
continue;
/*
* 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.
*/
vm = vmspace_acquire_ref(p);
if (vm == NULL)
continue;
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 nextproc;
}
/*
* only aiod changes vmspace, however it will be
* skipped because of the if statement above checking
* for P_SYSTEM
*/
if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM)
goto nextproc;
switch (p->p_state) {
default:
/* Don't swap out processes in any sort
* of 'special' state. */
break;
case PRS_NORMAL:
/*
* do not swapout a realtime process
* Check all the thread groups..
*/
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
if (PRI_IS_REALTIME(td->td_pri_class)) {
thread_unlock(td);
goto nextproc;
}
slptime = (ticks - td->td_slptick) / hz;
/*
* Guarantee swap_idle_threshold1
* time in memory.
*/
if (slptime < swap_idle_threshold1) {
thread_unlock(td);
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.
*/
if (!thread_safetoswapout(td)) {
thread_unlock(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) ||
(slptime < swap_idle_threshold2))) {
thread_unlock(td);
goto nextproc;
}
if (minslptime > slptime)
minslptime = slptime;
thread_unlock(td);
}
/*
* 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))) {
if (swapout(p) == 0)
didswap++;
PROC_UNLOCK(p);
vm_map_unlock(&vm->vm_map);
vmspace_free(vm);
sx_sunlock(&allproc_lock);
goto retry;
}
}
nextproc:
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
swapclear(p)
struct proc *p;
{
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
td->td_flags |= TDF_INMEM;
td->td_flags &= ~TDF_SWAPINREQ;
TD_CLR_SWAPPED(td);
if (TD_CAN_RUN(td))
setrunnable(td);
thread_unlock(td);
}
p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT);
p->p_flag |= P_INMEM;
}
static int
swapout(p)
struct proc *p;
{
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
#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_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM,
("swapout: lost a swapout race?"));
/*
* remember the process resident count
*/
p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
/*
* Check and mark all threads before we proceed.
*/
p->p_flag &= ~P_INMEM;
p->p_flag |= P_SWAPPINGOUT;
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
if (!thread_safetoswapout(td)) {
thread_unlock(td);
swapclear(p);
return (EBUSY);
}
td->td_flags &= ~TDF_INMEM;
TD_SET_SWAPPED(td);
thread_unlock(td);
}
td = FIRST_THREAD_IN_PROC(p);
++td->td_ru.ru_nswap;
PROC_UNLOCK(p);
/*
* This list is stable because all threads are now prevented from
* running. The list is only modified in the context of a running
* thread in this process.
*/
FOREACH_THREAD_IN_PROC(p, td)
vm_thread_swapout(td);
PROC_LOCK(p);
p->p_flag &= ~P_SWAPPINGOUT;
p->p_swtick = ticks;
return (0);
}
#endif /* !NO_SWAPPING */