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Don't keep cpu interrupts enabled during the lookup in vm_page_zero_idle().

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Lookup isn't done every time the system goes idle now, but it can still
take > 1800 instructions in the worst case, so if cpu interrupts are kept
disabled then it might lose 20 characters of sio input at 115200 bps.

Fixed style in vm_page_zero_idle().
This commit is contained in:
Bruce Evans 1997-03-29 04:35:26 +00:00
parent 1c8af87873
commit 83eab616cf
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=24361
2 changed files with 70 additions and 50 deletions
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60
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: vm_machdep.c,v 1.75 1997/02/22 09:33:01 peter Exp $
* $Id: vm_machdep.c,v 1.76 1997/03/22 04:28:16 dyson Exp $
*/
#include "npx.h"
@ -847,41 +847,51 @@ grow(p, sp)
}
/*
* prototype routine to implement the pre-zeroed page mechanism
* this routine is called from the idle loop.
* Implement the pre-zeroed page mechanism.
* This routine is called from the idle loop.
*/
int
vm_page_zero_idle() {
vm_page_zero_idle()
{
static int free_rover;
vm_page_t m;
static int free_rover = 0;
/* 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) &&
int s;
#ifdef WRONG
if (cnt.v_free_count <= cnt.v_interrupt_free_min)
return (0);
#endif
(m = vm_page_list_find(PQ_FREE, free_rover))) {
/*
* 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)
return (0);
s = splvm();
enable_intr();
m = vm_page_list_find(PQ_FREE, free_rover);
if (m != NULL) {
--(*vm_page_queues[m->queue].lcnt);
TAILQ_REMOVE(vm_page_queues[m->queue].pl, m, pageq);
enable_intr();
splx(s);
pmap_zero_page(VM_PAGE_TO_PHYS(m));
disable_intr();
(void)splvm();
m->queue = PQ_ZERO + m->pc;
++(*vm_page_queues[m->queue].lcnt);
TAILQ_INSERT_HEAD(vm_page_queues[m->queue].pl, m, pageq);
free_rover = (free_rover + PQ_PRIME3) & PQ_L2_MASK;
++vm_page_zero_count;
return 1;
}
return 0;
splx(s);
disable_intr();
return (1);
}

60
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: vm_machdep.c,v 1.75 1997/02/22 09:33:01 peter Exp $
* $Id: vm_machdep.c,v 1.76 1997/03/22 04:28:16 dyson Exp $
*/
#include "npx.h"
@ -847,41 +847,51 @@ grow(p, sp)
}
/*
* prototype routine to implement the pre-zeroed page mechanism
* this routine is called from the idle loop.
* Implement the pre-zeroed page mechanism.
* This routine is called from the idle loop.
*/
int
vm_page_zero_idle() {
vm_page_zero_idle()
{
static int free_rover;
vm_page_t m;
static int free_rover = 0;
/* 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) &&
int s;
#ifdef WRONG
if (cnt.v_free_count <= cnt.v_interrupt_free_min)
return (0);
#endif
(m = vm_page_list_find(PQ_FREE, free_rover))) {
/*
* 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)
return (0);
s = splvm();
enable_intr();
m = vm_page_list_find(PQ_FREE, free_rover);
if (m != NULL) {
--(*vm_page_queues[m->queue].lcnt);
TAILQ_REMOVE(vm_page_queues[m->queue].pl, m, pageq);
enable_intr();
splx(s);
pmap_zero_page(VM_PAGE_TO_PHYS(m));
disable_intr();
(void)splvm();
m->queue = PQ_ZERO + m->pc;
++(*vm_page_queues[m->queue].lcnt);
TAILQ_INSERT_HEAD(vm_page_queues[m->queue].pl, m, pageq);
free_rover = (free_rover + PQ_PRIME3) & PQ_L2_MASK;
++vm_page_zero_count;
return 1;
}
return 0;
splx(s);
disable_intr();
return (1);
}