From 96f973e7de4d8f2a11ecedfae50b316319fd1026 Mon Sep 17 00:00:00 2001 From: das Date: Wed, 12 Mar 2003 23:13:16 +0000 Subject: - When the VM daemon is out of swap space and looking for a process to kill, don't block on a map lock while holding the process lock. Instead, skip processes whose map locks are held and find something else to kill. - Add vm_map_trylock_read() to support the above. Reviewed by: alc, mike (mentor) --- sys/vm/vm_map.c | 15 +++++++++++++-- sys/vm/vm_map.h | 3 +++ sys/vm/vm_pageout.c | 9 +++++++-- 3 files changed, 23 insertions(+), 4 deletions(-) diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c index 33e819d..6e96db3 100644 --- a/sys/vm/vm_map.c +++ b/sys/vm/vm_map.c @@ -346,6 +346,8 @@ vmspace_exitfree(struct proc *p) * vmspace_swap_count() - count the approximate swap useage in pages for a * vmspace. * + * The map must be locked. + * * Swap useage is determined by taking the proportional swap used by * VM objects backing the VM map. To make up for fractional losses, * if the VM object has any swap use at all the associated map entries @@ -358,7 +360,6 @@ vmspace_swap_count(struct vmspace *vmspace) vm_map_entry_t cur; int count = 0; - vm_map_lock_read(map); for (cur = map->header.next; cur != &map->header; cur = cur->next) { vm_object_t object; @@ -374,7 +375,6 @@ vmspace_swap_count(struct vmspace *vmspace) } } } - vm_map_unlock_read(map); return (count); } @@ -439,6 +439,17 @@ _vm_map_trylock(vm_map_t map, const char *file, int line) } int +_vm_map_trylock_read(vm_map_t map, const char *file, int line) +{ + int error; + + error = map->system_map ? + !_mtx_trylock(&map->system_mtx, 0, file, line) : + lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT, NULL, curthread); + return (error == 0); +} + +int _vm_map_lock_upgrade(vm_map_t map, const char *file, int line) { diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h index eef9a48..b685a18 100644 --- a/sys/vm/vm_map.h +++ b/sys/vm/vm_map.h @@ -248,6 +248,7 @@ void _vm_map_unlock(vm_map_t map, const char *file, int line); void _vm_map_lock_read(vm_map_t map, const char *file, int line); void _vm_map_unlock_read(vm_map_t map, const char *file, int line); int _vm_map_trylock(vm_map_t map, const char *file, int line); +int _vm_map_trylock_read(vm_map_t map, const char *file, int line); int _vm_map_lock_upgrade(vm_map_t map, const char *file, int line); void _vm_map_lock_downgrade(vm_map_t map, const char *file, int line); int vm_map_unlock_and_wait(vm_map_t map, boolean_t user_wait); @@ -258,6 +259,8 @@ void vm_map_wakeup(vm_map_t map); #define vm_map_lock_read(map) _vm_map_lock_read(map, LOCK_FILE, LOCK_LINE) #define vm_map_unlock_read(map) _vm_map_unlock_read(map, LOCK_FILE, LOCK_LINE) #define vm_map_trylock(map) _vm_map_trylock(map, LOCK_FILE, LOCK_LINE) +#define vm_map_trylock_read(map) \ + _vm_map_trylock_read(map, LOCK_FILE, LOCK_LINE) #define vm_map_lock_upgrade(map) \ _vm_map_lock_upgrade(map, LOCK_FILE, LOCK_LINE) #define vm_map_lock_downgrade(map) \ diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c index 8e3c39f..dab4ae2 100644 --- a/sys/vm/vm_pageout.c +++ b/sys/vm/vm_pageout.c @@ -1214,8 +1214,13 @@ rescan0: /* * get the process size */ - size = vmspace_resident_count(p->p_vmspace) + - vmspace_swap_count(p->p_vmspace); + if (!vm_map_trylock_read(&p->p_vmspace->vm_map)) { + PROC_UNLOCK(p); + continue; + } + size = vmspace_swap_count(p->p_vmspace); + vm_map_unlock_read(&p->p_vmspace->vm_map); + size += vmspace_resident_count(p->p_vmspace); /* * if the this process is bigger than the biggest one * remember it. -- cgit v1.1