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Initial support for MADV_FREE, support for pages that we don't care

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about the contents anymore.  This gives us alot of the advantage of
freeing individual pages through munmap, but with almost none of the
overhead.
This commit is contained in:
John Dyson 1996-05-23 00:45:58 +00:00
parent b96e2ef41b
commit 0a47b48b9f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=15873
5 changed files with 45 additions and 60 deletions
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3
sys/sys/mman.h
View File

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)mman.h 8.2 (Berkeley) 1/9/95
* $Id: mman.h,v 1.12 1996/03/11 02:09:09 hsu Exp $
* $Id: mman.h,v 1.13 1996/05/19 07:36:41 dyson Exp $
*/
#ifndef _SYS_MMAN_H_
@ -83,6 +83,7 @@
#define MADV_SEQUENTIAL 2 /* expect sequential page references */
#define MADV_WILLNEED 3 /* will need these pages */
#define MADV_DONTNEED 4 /* dont need these pages */
#define MADV_FREE 5 /* dont need these pages, and junk contents */
/*
* Return bits from mincore

28
sys/vm/swap_pager.c
View File

@ -39,7 +39,7 @@
* from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
*
* @(#)swap_pager.c 8.9 (Berkeley) 3/21/94
* $Id: swap_pager.c,v 1.65 1996/05/03 21:01:47 phk Exp $
* $Id: swap_pager.c,v 1.66 1996/05/18 03:37:32 dyson Exp $
*/
/*
@ -438,6 +438,32 @@ swap_pager_freespace(object, start, size)
splx(s);
}
/*
* same as freespace, but don't free, just force a DMZ next time
*/
void
swap_pager_dmzspace(object, start, size)
vm_object_t object;
vm_pindex_t start;
vm_size_t size;
{
vm_pindex_t i;
int s;
s = splbio();
for (i = start; i < start + size; i += 1) {
int valid;
daddr_t *addr = swap_pager_diskaddr(object, i, &valid);
if (addr && *addr != SWB_EMPTY) {
if (valid) {
swap_pager_setvalid(object, i, 0);
}
}
}
splx(s);
}
static void
swap_pager_free_swap(object)
vm_object_t object;

3
sys/vm/swap_pager.h
View File

@ -36,7 +36,7 @@
* SUCH DAMAGE.
*
* from: @(#)swap_pager.h 7.1 (Berkeley) 12/5/90
* $Id: swap_pager.h,v 1.14 1996/01/30 23:02:29 mpp Exp $
* $Id: swap_pager.h,v 1.15 1996/03/03 21:11:06 dyson Exp $
*/
/*
@ -73,6 +73,7 @@ int swap_pager_swp_alloc __P((vm_object_t, int));
void swap_pager_copy __P((vm_object_t, vm_pindex_t, vm_object_t,
vm_pindex_t, vm_pindex_t));
void swap_pager_freespace __P((vm_object_t, vm_pindex_t, vm_size_t));
void swap_pager_dmzspace __P((vm_object_t, vm_pindex_t, vm_size_t));
void swap_pager_swap_init __P((void));
#endif

3
sys/vm/vm_map.c
View File

@ -61,7 +61,7 @@
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $Id: vm_map.c,v 1.45 1996/05/18 03:37:43 dyson Exp $
* $Id: vm_map.c,v 1.46 1996/05/19 07:36:46 dyson Exp $
*/
/*
@ -1225,6 +1225,7 @@ vm_map_madvise(map, pmap, start, end, advise)
* Right now, we could handle DONTNEED and WILLNEED with common code.
* They are mostly the same, except for the potential async reads (NYI).
*/
case MADV_FREE:
case MADV_DONTNEED:
{
vm_pindex_t pindex;

68
sys/vm/vm_object.c
View File

@ -61,7 +61,7 @@
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $Id: vm_object.c,v 1.71 1996/05/21 05:26:27 dyson Exp $
* $Id: vm_object.c,v 1.72 1996/05/21 17:13:31 dyson Exp $
*/
/*
@ -709,7 +709,9 @@ vm_object_madvise(object, pindex, count, advise)
if (advise == MADV_WILLNEED) {
if (m->queue != PQ_ACTIVE)
vm_page_activate(m);
} else if (advise == MADV_DONTNEED) {
} else if ((advise == MADV_DONTNEED) ||
((advise == MADV_FREE) &&
((object->type != OBJT_DEFAULT) && (object->type != OBJT_SWAP)))) {
/*
* If the upper level VM system doesn't think that
* the page is dirty, check the pmap layer.
@ -732,64 +734,18 @@ vm_object_madvise(object, pindex, count, advise)
vm_page_protect(m, VM_PROT_NONE);
vm_page_deactivate(m);
}
} else if (advise == MADV_FREE) {
/*
* Force a demand-zero on next ref
*/
if (object->type == OBJT_SWAP)
swap_pager_dmzspace(object, m->pindex, 1);
vm_page_protect(m, VM_PROT_NONE);
vm_page_free(m);
}
}
}
/*
* vm_object_copy:
*
* Create a new object which is a copy of an existing
* object, and mark all of the pages in the existing
* object 'copy-on-write'. The new object has one reference.
* Returns the new object.
*
* May defer the copy until later if the object is not backed
* up by a non-default pager.
*
*/
void
vm_object_copy(src_object, src_offset,
dst_object, dst_offset, src_needs_copy)
register vm_object_t src_object;
vm_pindex_t src_offset;
vm_object_t *dst_object;/* OUT */
vm_pindex_t *dst_offset;/* OUT */
boolean_t *src_needs_copy; /* OUT */
{
if (src_object == NULL) {
/*
* Nothing to copy
*/
*dst_object = NULL;
*dst_offset = 0;
*src_needs_copy = FALSE;
return;
}
/*
* Try to collapse the object before copying it.
*/
if (src_object->handle == NULL &&
(src_object->type == OBJT_DEFAULT ||
src_object->type == OBJT_SWAP))
vm_object_collapse(src_object);
/*
* Make another reference to the object
*/
src_object->ref_count++;
*dst_object = src_object;
*dst_offset = src_offset;
/*
* Must make a shadow when write is desired
*/
*src_needs_copy = TRUE;
return;
}
/*
* vm_object_shadow:
*