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Add hysteresis to alpha version of vm_page_zero_idle().

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This commit is contained in:
Matthew Dillon 1999-02-08 00:47:32 +00:00
parent faa273d5c2
commit d718be7be7
3 changed files with 51 additions and 42 deletions
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31
sys/alpha/alpha/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 1.8 1999/01/26 02:49:51 julian Exp $
* $Id: vm_machdep.c,v 1.9 1999/02/08 00:37:35 dillon Exp $
*/
/*
* Copyright (c) 1994, 1995, 1996 Carnegie-Mellon University.
@ -447,29 +447,30 @@ int
vm_page_zero_idle()
{
static int free_rover;
static int zero_state;
vm_page_t m;
int s;
/*
* 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.
* Attempt to maintain approximately 1/2 of our free pages in a
* PG_ZERO'd state. Add some hysteresis to (attempt to) avoid
* generally zeroing a page when the system is near steady-state.
* Otherwise we might get 'flutter' during disk I/O / IPC or
* fast sleeps. We also do not want to be continuously zeroing
* pages because doing so may flush our L1 and L2 caches too much.
*/
if (cnt.v_free_count - vm_page_zero_count <= cnt.v_free_reserved / 2)
return (0);
if (zero_state && vm_page_zero_count >= cnt.v_free_count / 3)
return(0);
if (vm_page_zero_count >= cnt.v_free_count / 2)
return(0);
#ifdef SMP
if (try_mplock()) {
#endif
s = splvm();
m = vm_page_list_find(PQ_FREE, free_rover, FALSE);
zero_state = 0;
if (m != NULL && (m->flags & PG_ZERO) == 0) {
--(*vm_page_queues[m->queue].lcnt);
TAILQ_REMOVE(vm_page_queues[m->queue].pl, m, pageq);
@ -490,6 +491,8 @@ vm_page_zero_idle()
pageq);
++vm_page_zero_count;
++cnt_prezero;
if (vm_page_zero_count >= cnt.v_free_count / 2)
zero_state = 1;
}
free_rover = (free_rover + PQ_PRIME3) & PQ_L2_MASK;
splx(s);

31
sys/powerpc/aim/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 1.8 1999/01/26 02:49:51 julian Exp $
* $Id: vm_machdep.c,v 1.9 1999/02/08 00:37:35 dillon Exp $
*/
/*
* Copyright (c) 1994, 1995, 1996 Carnegie-Mellon University.
@ -447,29 +447,30 @@ int
vm_page_zero_idle()
{
static int free_rover;
static int zero_state;
vm_page_t m;
int s;
/*
* 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.
* Attempt to maintain approximately 1/2 of our free pages in a
* PG_ZERO'd state. Add some hysteresis to (attempt to) avoid
* generally zeroing a page when the system is near steady-state.
* Otherwise we might get 'flutter' during disk I/O / IPC or
* fast sleeps. We also do not want to be continuously zeroing
* pages because doing so may flush our L1 and L2 caches too much.
*/
if (cnt.v_free_count - vm_page_zero_count <= cnt.v_free_reserved / 2)
return (0);
if (zero_state && vm_page_zero_count >= cnt.v_free_count / 3)
return(0);
if (vm_page_zero_count >= cnt.v_free_count / 2)
return(0);
#ifdef SMP
if (try_mplock()) {
#endif
s = splvm();
m = vm_page_list_find(PQ_FREE, free_rover, FALSE);
zero_state = 0;
if (m != NULL && (m->flags & PG_ZERO) == 0) {
--(*vm_page_queues[m->queue].lcnt);
TAILQ_REMOVE(vm_page_queues[m->queue].pl, m, pageq);
@ -490,6 +491,8 @@ vm_page_zero_idle()
pageq);
++vm_page_zero_count;
++cnt_prezero;
if (vm_page_zero_count >= cnt.v_free_count / 2)
zero_state = 1;
}
free_rover = (free_rover + PQ_PRIME3) & PQ_L2_MASK;
splx(s);

31
sys/powerpc/powerpc/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 1.8 1999/01/26 02:49:51 julian Exp $
* $Id: vm_machdep.c,v 1.9 1999/02/08 00:37:35 dillon Exp $
*/
/*
* Copyright (c) 1994, 1995, 1996 Carnegie-Mellon University.
@ -447,29 +447,30 @@ int
vm_page_zero_idle()
{
static int free_rover;
static int zero_state;
vm_page_t m;
int s;
/*
* 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.
* Attempt to maintain approximately 1/2 of our free pages in a
* PG_ZERO'd state. Add some hysteresis to (attempt to) avoid
* generally zeroing a page when the system is near steady-state.
* Otherwise we might get 'flutter' during disk I/O / IPC or
* fast sleeps. We also do not want to be continuously zeroing
* pages because doing so may flush our L1 and L2 caches too much.
*/
if (cnt.v_free_count - vm_page_zero_count <= cnt.v_free_reserved / 2)
return (0);
if (zero_state && vm_page_zero_count >= cnt.v_free_count / 3)
return(0);
if (vm_page_zero_count >= cnt.v_free_count / 2)
return(0);
#ifdef SMP
if (try_mplock()) {
#endif
s = splvm();
m = vm_page_list_find(PQ_FREE, free_rover, FALSE);
zero_state = 0;
if (m != NULL && (m->flags & PG_ZERO) == 0) {
--(*vm_page_queues[m->queue].lcnt);
TAILQ_REMOVE(vm_page_queues[m->queue].pl, m, pageq);
@ -490,6 +491,8 @@ vm_page_zero_idle()
pageq);
++vm_page_zero_count;
++cnt_prezero;
if (vm_page_zero_count >= cnt.v_free_count / 2)
zero_state = 1;
}
free_rover = (free_rover + PQ_PRIME3) & PQ_L2_MASK;
splx(s);