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Decrease the latency/overhead in the prezero code when there is

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an adequate number of prezeroed pages.
This commit is contained in:
John Dyson 1997-03-22 04:28:16 +00:00
parent c16cb2c78b
commit 8e56e56134
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=24099
2 changed files with 34 additions and 4 deletions
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19
sys/amd64/amd64/vm_machdep.c
View File

@ -38,7 +38,7 @@
*
* from: @(#)vm_machdep.c 7.3 (Berkeley) 5/13/91
* Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
* $Id$
* $Id: vm_machdep.c,v 1.75 1997/02/22 09:33:01 peter Exp $
*/
#include "npx.h"
@ -854,7 +854,22 @@ int
vm_page_zero_idle() {
vm_page_t m;
static int free_rover = 0;
if ((cnt.v_free_count > cnt.v_interrupt_free_min) &&
/* XXX
* We stop zeroing pages when there are sufficent prezeroed pages.
* This threshold isn't really needed, except we want to
* bypass unneeded calls to vm_page_list_find, and the
* associated cache flush and latency. The pre-zero will
* still be called when there are significantly more
* non-prezeroed pages than zeroed pages. The threshold
* of half the number of reserved pages is arbitrary, but
* approximately the right amount. Eventually, we should
* perhaps interrupt the zero operation when a process
* is found to be ready to run.
*/
if (((cnt.v_free_count - vm_page_zero_count) > (cnt.v_free_reserved / 2)) &&
#ifdef NOT_NEEDED
(cnt.v_free_count > cnt.v_interrupt_free_min) &&
#endif
(m = vm_page_list_find(PQ_FREE, free_rover))) {
--(*vm_page_queues[m->queue].lcnt);
TAILQ_REMOVE(vm_page_queues[m->queue].pl, m, pageq);

19
sys/i386/i386/vm_machdep.c
View File

@ -38,7 +38,7 @@
*
* from: @(#)vm_machdep.c 7.3 (Berkeley) 5/13/91
* Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
* $Id$
* $Id: vm_machdep.c,v 1.75 1997/02/22 09:33:01 peter Exp $
*/
#include "npx.h"
@ -854,7 +854,22 @@ int
vm_page_zero_idle() {
vm_page_t m;
static int free_rover = 0;
if ((cnt.v_free_count > cnt.v_interrupt_free_min) &&
/* XXX
* We stop zeroing pages when there are sufficent prezeroed pages.
* This threshold isn't really needed, except we want to
* bypass unneeded calls to vm_page_list_find, and the
* associated cache flush and latency. The pre-zero will
* still be called when there are significantly more
* non-prezeroed pages than zeroed pages. The threshold
* of half the number of reserved pages is arbitrary, but
* approximately the right amount. Eventually, we should
* perhaps interrupt the zero operation when a process
* is found to be ready to run.
*/
if (((cnt.v_free_count - vm_page_zero_count) > (cnt.v_free_reserved / 2)) &&
#ifdef NOT_NEEDED
(cnt.v_free_count > cnt.v_interrupt_free_min) &&
#endif
(m = vm_page_list_find(PQ_FREE, free_rover))) {
--(*vm_page_queues[m->queue].lcnt);
TAILQ_REMOVE(vm_page_queues[m->queue].pl, m, pageq);