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f-stack/freebsd/vm/vm_glue.c

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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 "opt_kstack_usage_prof.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/sched.h>
#include <sys/sf_buf.h>
#include <sys/shm.h>
#include <sys/vmmeter.h>
#include <sys/vmem.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/_kstack_cache.h>
#include <sys/eventhandler.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 <machine/cpu.h>
#ifndef NO_SWAPPING
static int swapout(struct proc *);
static void swapclear(struct proc *);
static void vm_thread_swapin(struct thread *td);
static void vm_thread_swapout(struct thread *td);
#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));
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 conjunction 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);
#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 + vm_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;
vm_pindex_t pindex;
int rv;
VM_OBJECT_WLOCK(object);
pindex = OFF_TO_IDX(offset);
m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
if (m->valid != VM_PAGE_BITS_ALL) {
rv = vm_pager_get_pages(object, &m, 1, NULL, NULL);
if (rv != VM_PAGER_OK) {
vm_page_lock(m);
vm_page_free(m);
vm_page_unlock(m);
m = NULL;
goto out;
}
}
vm_page_xunbusy(m);
vm_page_lock(m);
vm_page_hold(m);
vm_page_activate(m);
vm_page_unlock(m);
out:
VM_OBJECT_WUNLOCK(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(m);
vm_page_unhold(m);
vm_page_unlock(m);
}
void
vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz)
{
pmap_sync_icache(map->pmap, va, sz);
}
struct kstack_cache_entry *kstack_cache;
static int kstack_cache_size = 128;
static int kstacks;
static struct mtx kstack_cache_mtx;
MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF);
SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0,
"");
SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0,
"");
#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];
struct kstack_cache_entry *ks_ce;
int i;
/* Bounds check */
if (pages <= 1)
pages = kstack_pages;
else if (pages > KSTACK_MAX_PAGES)
pages = KSTACK_MAX_PAGES;
if (pages == kstack_pages) {
mtx_lock(&kstack_cache_mtx);
if (kstack_cache != NULL) {
ks_ce = kstack_cache;
kstack_cache = ks_ce->next_ks_entry;
mtx_unlock(&kstack_cache_mtx);
td->td_kstack_obj = ks_ce->ksobj;
td->td_kstack = (vm_offset_t)ks_ce;
td->td_kstack_pages = kstack_pages;
return (1);
}
mtx_unlock(&kstack_cache_mtx);
}
/*
* Allocate an object for the kstack.
*/
ksobj = vm_object_allocate(OBJT_DEFAULT, pages);
/*
* Get a kernel virtual address for this thread's kstack.
*/
#if defined(__mips__)
/*
* We need to align the kstack's mapped address to fit within
* a single TLB entry.
*/
if (vmem_xalloc(kernel_arena, (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE,
PAGE_SIZE * 2, 0, 0, VMEM_ADDR_MIN, VMEM_ADDR_MAX,
M_BESTFIT | M_NOWAIT, &ks)) {
ks = 0;
}
#else
ks = kva_alloc((pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
#endif
if (ks == 0) {
printf("vm_thread_new: kstack allocation failed\n");
vm_object_deallocate(ksobj);
return (0);
}
atomic_add_int(&kstacks, 1);
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_WLOCK(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_WIRED);
ma[i] = m;
m->valid = VM_PAGE_BITS_ALL;
}
VM_OBJECT_WUNLOCK(ksobj);
pmap_qenter(ks, ma, pages);
return (1);
}
static void
vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages)
{
vm_page_t m;
int i;
atomic_add_int(&kstacks, -1);
pmap_qremove(ks, pages);
VM_OBJECT_WLOCK(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(m);
vm_page_unwire(m, PQ_NONE);
vm_page_free(m);
vm_page_unlock(m);
}
VM_OBJECT_WUNLOCK(ksobj);
vm_object_deallocate(ksobj);
kva_free(ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
(pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
}
/*
* Dispose of a thread's kernel stack.
*/
void
vm_thread_dispose(struct thread *td)
{
vm_object_t ksobj;
vm_offset_t ks;
struct kstack_cache_entry *ks_ce;
int pages;
pages = td->td_kstack_pages;
ksobj = td->td_kstack_obj;
ks = td->td_kstack;
td->td_kstack = 0;
td->td_kstack_pages = 0;
if (pages == kstack_pages && kstacks <= kstack_cache_size) {
ks_ce = (struct kstack_cache_entry *)ks;
ks_ce->ksobj = ksobj;
mtx_lock(&kstack_cache_mtx);
ks_ce->next_ks_entry = kstack_cache;
kstack_cache = ks_ce;
mtx_unlock(&kstack_cache_mtx);
return;
}
vm_thread_stack_dispose(ksobj, ks, pages);
}
static void
vm_thread_stack_lowmem(void *nulll)
{
struct kstack_cache_entry *ks_ce, *ks_ce1;
mtx_lock(&kstack_cache_mtx);
ks_ce = kstack_cache;
kstack_cache = NULL;
mtx_unlock(&kstack_cache_mtx);
while (ks_ce != NULL) {
ks_ce1 = ks_ce;
ks_ce = ks_ce->next_ks_entry;
vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1,
kstack_pages);
}
}
static void
kstack_cache_init(void *nulll)
{
EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL,
EVENTHANDLER_PRI_ANY);
}
SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL);
#ifdef KSTACK_USAGE_PROF
/*
* Track maximum stack used by a thread in kernel.
*/
static int max_kstack_used;
SYSCTL_INT(_debug, OID_AUTO, max_kstack_used, CTLFLAG_RD,
&max_kstack_used, 0,
"Maxiumum stack depth used by a thread in kernel");
void
intr_prof_stack_use(struct thread *td, struct trapframe *frame)
{
vm_offset_t stack_top;
vm_offset_t current;
int used, prev_used;
/*
* Testing for interrupted kernel mode isn't strictly
* needed. It optimizes the execution, since interrupts from
* usermode will have only the trap frame on the stack.
*/
if (TRAPF_USERMODE(frame))
return;
stack_top = td->td_kstack + td->td_kstack_pages * PAGE_SIZE;
current = (vm_offset_t)(uintptr_t)&stack_top;
/*
* Try to detect if interrupt is using kernel thread stack.
* Hardware could use a dedicated stack for interrupt handling.
*/
if (stack_top <= current || current < td->td_kstack)
return;
used = stack_top - current;
for (;;) {
prev_used = max_kstack_used;
if (prev_used >= used)
break;
if (atomic_cmpset_int(&max_kstack_used, prev_used, used))
break;
}
}
#endif /* KSTACK_USAGE_PROF */
#ifndef NO_SWAPPING
/*
* Allow a thread's kernel stack to be paged out.
*/
static 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_WLOCK(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_dirty(m);
vm_page_lock(m);
vm_page_unwire(m, PQ_INACTIVE);
vm_page_unlock(m);
}
VM_OBJECT_WUNLOCK(ksobj);
}
/*
* Bring the kernel stack for a specified thread back in.
*/
static void
vm_thread_swapin(struct thread *td)
{
vm_object_t ksobj;
vm_page_t ma[KSTACK_MAX_PAGES];
int pages;
pages = td->td_kstack_pages;
ksobj = td->td_kstack_obj;
VM_OBJECT_WLOCK(ksobj);
for (int i = 0; i < pages; i++)
ma[i] = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL |
VM_ALLOC_WIRED);
for (int i = 0; i < pages;) {
int j, a, count, rv;
vm_page_assert_xbusied(ma[i]);
if (ma[i]->valid == VM_PAGE_BITS_ALL) {
vm_page_xunbusy(ma[i]);
i++;
continue;
}
vm_object_pip_add(ksobj, 1);
for (j = i + 1; j < pages; j++)
if (ma[j]->valid == VM_PAGE_BITS_ALL)
break;
rv = vm_pager_has_page(ksobj, ma[i]->pindex, NULL, &a);
KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i]));
count = min(a + 1, j - i);
rv = vm_pager_get_pages(ksobj, ma + i, count, NULL, NULL);
KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d",
__func__, td->td_proc->p_pid));
vm_object_pip_wakeup(ksobj);
for (j = i; j < i + count; j++)
vm_page_xunbusy(ma[j]);
i += count;
}
VM_OBJECT_WUNLOCK(ksobj);
pmap_qenter(td->td_kstack, ma, pages);
cpu_thread_swapin(td);
}
#endif /* !NO_SWAPPING */
/*
* 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 upon 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 */
}
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.
*/
void
swapper(void)
{
struct proc *p;
struct thread *td;
struct proc *pp;
int slptime;
int swtime;
int ppri;
int pri;
loop:
if (vm_page_count_min()) {
VM_WAIT;
goto loop;
}
pp = NULL;
ppri = INT_MIN;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
PROC_LOCK(p);
if (p->p_state == PRS_NEW ||
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) {
tsleep(&proc0, PVM, "swapin", 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_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) {
PROC_UNLOCK(p);
goto loop;
}
/*
* We would like to bring someone in. (only if there is space).
* [What checks the space? ]
*/
faultin(p);
PROC_UNLOCK(p);
goto loop;
}
void
kick_proc0(void)
{
wakeup(&proc0);
}
#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");
/*
* First, if any processes have been sleeping or stopped for at least
* "swap_idle_threshold1" seconds, they are swapped out. If, however,
* no such processes exist, then the longest-sleeping or stopped
* process is swapped out. Finally, and only as a last resort, if
* there are no sleeping or stopped processes, the longest-resident
* process is swapped out.
*/
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;
PROC_LOCK(p);
/*
* Watch out for a process in
* creation. It may have no
* address space or lock yet.
*/
if (p->p_state == PRS_NEW) {
PROC_UNLOCK(p);
continue;
}
/*
* An aio daemon switches its
* address space while running.
* Perform a quick check whether
* a process has P_SYSTEM.
* Filter out exiting processes.
*/
if ((p->p_flag & (P_SYSTEM | P_WEXIT)) != 0) {
PROC_UNLOCK(p);
continue;
}
_PHOLD_LITE(p);
PROC_UNLOCK(p);
sx_sunlock(&allproc_lock);
/*
* 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)
goto nextproc2;
if (!vm_map_trylock(&vm->vm_map))
goto nextproc1;
PROC_LOCK(p);
if (p->p_lock != 1 || (p->p_flag & (P_STOPPED_SINGLE |
P_TRACED | P_SYSTEM)) != 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))) {
_PRELE(p);
if (swapout(p) == 0)
didswap++;
PROC_UNLOCK(p);
vm_map_unlock(&vm->vm_map);
vmspace_free(vm);
goto retry;
}
}
nextproc:
PROC_UNLOCK(p);
vm_map_unlock(&vm->vm_map);
nextproc1:
vmspace_free(vm);
nextproc2:
sx_slock(&allproc_lock);
PRELE(p);
}
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))
if (setrunnable(td)) {
#ifdef INVARIANTS
/*
* XXX: We just cleared TDI_SWAPPED
* above and set TDF_INMEM, so this
* should never happen.
*/
panic("not waking up swapper");
#endif
}
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 */
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