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Move the implementation of the vmspace_swap_count() (used only in

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the "toss the largest process" emergency handling) from vm_map.c to
swap_pager.c.

The quantity calculated depends strongly on the internals of the
swap_pager and by moving it, we no longer need to expose the
internal metrics of the swap_pager to the world.
This commit is contained in:
Poul-Henning Kamp 2003-07-18 10:47:58 +00:00
parent 567104a148
commit ec38b344cb
3 changed files with 65 additions and 64 deletions
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65
sys/vm/swap_pager.c
View File

@ -111,6 +111,33 @@ __FBSDID("$FreeBSD$");
#define NSWAPDEV 4
#endif
/*
* SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, or 16
* pages per allocation. We recommend you stick with the default of 8.
* The 16-page limit is due to the radix code (kern/subr_blist.c).
*/
#ifndef MAX_PAGEOUT_CLUSTER
#define MAX_PAGEOUT_CLUSTER 16
#endif
#if !defined(SWB_NPAGES)
#define SWB_NPAGES MAX_PAGEOUT_CLUSTER
#endif
/*
* Piecemeal swap metadata structure. Swap is stored in a radix tree.
*
* If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix
* is basically 8. Assuming PAGE_SIZE == 4096, one tree level represents
* 32K worth of data, two levels represent 256K, three levels represent
* 2 MBytes. This is acceptable.
*
* Overall memory utilization is about the same as the old swap structure.
*/
#define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
#define SWAP_META_PAGES (SWB_NPAGES * 2)
#define SWAP_META_MASK (SWAP_META_PAGES - 1)
typedef int32_t swblk_t; /* swap offset */
struct swblock {
@ -2716,3 +2743,41 @@ SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswdev, 0,
"Number of swap devices");
SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info,
"Swap statistics by device");
/*
* 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
* count for at least 1 swap page.
*/
int
vmspace_swap_count(struct vmspace *vmspace)
{
vm_map_t map = &vmspace->vm_map;
vm_map_entry_t cur;
int count = 0;
for (cur = map->header.next; cur != &map->header; cur = cur->next) {
vm_object_t object;
if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 &&
(object = cur->object.vm_object) != NULL) {
VM_OBJECT_LOCK(object);
if (object->type == OBJT_SWAP &&
object->un_pager.swp.swp_bcount != 0) {
int n = (cur->end - cur->start) / PAGE_SIZE;
count += object->un_pager.swp.swp_bcount *
SWAP_META_PAGES * n / object->size + 1;
}
VM_OBJECT_UNLOCK(object);
}
}
return (count);
}

27
sys/vm/swap_pager.h
View File

@ -65,33 +65,6 @@ struct swdevt {
#ifdef _KERNEL
/*
* SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, or 16
* pages per allocation. We recommend you stick with the default of 8.
* The 16-page limit is due to the radix code (kern/subr_blist.c).
*/
#ifndef MAX_PAGEOUT_CLUSTER
#define MAX_PAGEOUT_CLUSTER 16
#endif
#if !defined(SWB_NPAGES)
#define SWB_NPAGES MAX_PAGEOUT_CLUSTER
#endif
/*
* Piecemeal swap metadata structure. Swap is stored in a radix tree.
*
* If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix
* is basically 8. Assuming PAGE_SIZE == 4096, one tree level represents
* 32K worth of data, two levels represent 256K, three levels represent
* 2 MBytes. This is acceptable.
*
* Overall memory utilization is about the same as the old swap structure.
*/
#define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
#define SWAP_META_PAGES (SWB_NPAGES * 2)
#define SWAP_META_MASK (SWAP_META_PAGES - 1)
extern int swap_pager_full;
extern int vm_swap_size;

37
sys/vm/vm_map.c
View File

@ -342,43 +342,6 @@ vmspace_exitfree(struct proc *p)
vmspace_dofree(vm);
}
/*
* 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
* count for at least 1 swap page.
*/
int
vmspace_swap_count(struct vmspace *vmspace)
{
vm_map_t map = &vmspace->vm_map;
vm_map_entry_t cur;
int count = 0;
for (cur = map->header.next; cur != &map->header; cur = cur->next) {
vm_object_t object;
if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 &&
(object = cur->object.vm_object) != NULL) {
VM_OBJECT_LOCK(object);
if (object->type == OBJT_SWAP &&
object->un_pager.swp.swp_bcount != 0) {
int n = (cur->end - cur->start) / PAGE_SIZE;
count += object->un_pager.swp.swp_bcount *
SWAP_META_PAGES * n / object->size + 1;
}
VM_OBJECT_UNLOCK(object);
}
}
return (count);
}
void
_vm_map_lock(vm_map_t map, const char *file, int line)
{