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Simple changes to paging algorithms...but boy do they make a difference.

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FreeBSD's paging performance has never been better. Wow.

Submitted by:	John Dyson
This commit is contained in:
dg 1994-09-06 11:28:46 +00:00
parent a4e49c14f0
commit 0a37b9feee
2 changed files with 100 additions and 21 deletions
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3
sys/vm/vm_page.h
View File

@ -61,7 +61,7 @@
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $Id: vm_page.h,v 1.3 1994/08/02 07:55:32 davidg Exp $
* $Id: vm_page.h,v 1.4 1994/08/04 03:06:45 davidg Exp $
*/
/*
@ -111,6 +111,7 @@ struct vm_page {
u_short flags; /* see below */
short hold_count; /* page hold count */
u_short act_count; /* page usage count */
u_short busy; /* page busy count */
vm_offset_t phys_addr; /* physical address of page */
};

118
sys/vm/vm_pageout.c
View File

@ -65,7 +65,7 @@
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $Id: vm_pageout.c,v 1.8 1994/08/18 22:36:07 wollman Exp $
* $Id: vm_pageout.c,v 1.9 1994/08/30 18:27:44 davidg Exp $
*/
/*
@ -89,6 +89,7 @@ int vm_pageout_free_min = 0; /* Stop pageout to wait for pagers at this free lev
int vm_pageout_pages_needed = 0; /* flag saying that the pageout daemon needs pages */
int vm_page_pagesfreed;
int vm_desired_cache_size;
extern int npendingio;
extern int hz;
@ -182,7 +183,8 @@ vm_pageout_clean(m, sync)
return 0;
}
if ((m->flags & PG_BUSY) || (m->hold_count != 0)) {
if ((m->busy != 0) ||
(m->flags & PG_BUSY) || (m->hold_count != 0)) {
return 0;
}
}
@ -196,6 +198,7 @@ vm_pageout_clean(m, sync)
if (( ((ms[i]->flags & (PG_CLEAN|PG_INACTIVE|PG_BUSY)) == PG_INACTIVE)
|| ( (ms[i]->flags & PG_CLEAN|PG_BUSY) == 0 && sync == VM_PAGEOUT_FORCE))
&& (ms[i]->wire_count == 0)
&& (ms[i]->busy == 0)
&& (ms[i]->hold_count == 0))
pageout_count++;
else
@ -305,8 +308,10 @@ vm_pageout_clean(m, sync)
PAGE_WAKEUP(ms[i]);
if (--object->paging_in_progress == 0)
wakeup((caddr_t) object);
if (pmap_is_referenced(VM_PAGE_TO_PHYS(ms[i]))) {
if ((ms[i]->flags & PG_REFERENCED) ||
pmap_is_referenced(VM_PAGE_TO_PHYS(ms[i]))) {
pmap_clear_reference(VM_PAGE_TO_PHYS(ms[i]));
ms[i]->flags &= ~PG_REFERENCED;
if( ms[i]->flags & PG_INACTIVE)
vm_page_activate(ms[i]);
}
@ -366,8 +371,10 @@ vm_pageout_object_deactivate_pages(map, object, count)
if ((p->flags & (PG_ACTIVE|PG_BUSY)) == PG_ACTIVE &&
p->wire_count == 0 &&
p->hold_count == 0 &&
p->busy == 0 &&
pmap_page_exists(vm_map_pmap(map), VM_PAGE_TO_PHYS(p))) {
if (!pmap_is_referenced(VM_PAGE_TO_PHYS(p))) {
if (!pmap_is_referenced(VM_PAGE_TO_PHYS(p)) &&
(p->flags & PG_REFERENCED) == 0) {
p->act_count -= min(p->act_count, ACT_DECLINE);
/*
* if the page act_count is zero -- then we deactivate
@ -405,6 +412,7 @@ vm_pageout_object_deactivate_pages(map, object, count)
* Move the page to the bottom of the queue.
*/
pmap_clear_reference(VM_PAGE_TO_PHYS(p));
p->flags &= ~PG_REFERENCED;
if (p->act_count < ACT_MAX)
p->act_count += ACT_ADVANCE;
@ -480,8 +488,78 @@ vm_pageout_scan()
vm_object_t object;
int s;
int force_wakeup = 0;
int cache_size, orig_cache_size;
/*
* deactivate pages for objects on the cached queue are 0
* we manage the cached memory by attempting to keep it
* at about the desired level.
* we deactivate the pages for the oldest cached objects
* first.
*/
orig_cache_size = 0;
object = vm_object_cached_list.tqh_first;
while( object) {
orig_cache_size += object->resident_page_count;
object = object->cached_list.tqe_next;
}
redeact:
cache_size = orig_cache_size;
object = vm_object_cached_list.tqh_first;
vm_object_cache_lock();
while ( object && (cnt.v_inactive_count < cnt.v_inactive_target) &&
(cache_size >= vm_desired_cache_size)) {
vm_object_cache_unlock();
if (object != vm_object_lookup(object->pager))
panic("vm_object_deactivate: I'm sooo confused.");
/*
* if there are no resident pages -- get rid of the object
*/
if( object->resident_page_count == 0) {
pager_cache(object, FALSE);
goto redeact;
} else {
/*
* if there are resident pages -- deactivate them
*/
vm_object_deactivate_pages(object);
cache_size -= object->resident_page_count;
object = object->cached_list.tqe_next;
}
vm_object_cache_lock();
}
vm_object_cache_unlock();
morefree:
/*
* deactivate pages for objects whose ref-counts are 0
*/
simple_lock(&vm_object_list_lock);
object = vm_object_list.tqh_first;
while (object) {
if( cnt.v_inactive_count >= cnt.v_inactive_target)
break;
if( (object->ref_count == 0) && (object->resident_page_count != 0)) {
vm_object_deactivate_pages(object);
}
object = object->object_list.tqe_next;
}
simple_unlock(&vm_object_list_lock);
/*
* now check malloc area or swap processes out if we are in low
* memory conditions
*/
if (cnt.v_free_count <= cnt.v_free_min) {
/*
* swap out inactive processes
*/
swapout_threads();
}
/*
* scan the processes for exceeding their rlimits or if process
* is swapped out -- deactivate pages
@ -572,7 +650,7 @@ vm_pageout_scan()
/*
* dont mess with busy pages
*/
if (m->flags & PG_BUSY) {
if (m->busy || (m->flags & PG_BUSY)) {
m = next;
continue;
}
@ -585,7 +663,9 @@ vm_pageout_scan()
*/
if (m->flags & PG_CLEAN) {
if ((cnt.v_free_count > vm_pageout_free_min) /* XXX */
&& pmap_is_referenced(VM_PAGE_TO_PHYS(m))) {
&& ((pmap_is_referenced(VM_PAGE_TO_PHYS(m)) ||
(m->flags & PG_REFERENCED) != 0))) {
m->flags &= ~PG_REFERENCED;
vm_page_activate(m);
} else if (!m->act_count) {
pmap_page_protect(VM_PAGE_TO_PHYS(m),
@ -599,9 +679,11 @@ vm_pageout_scan()
}
} else if ((m->flags & PG_LAUNDRY) && maxlaunder > 0) {
int written;
if (pmap_is_referenced(VM_PAGE_TO_PHYS(m))) {
if (pmap_is_referenced(VM_PAGE_TO_PHYS(m)) ||
((m->flags & PG_REFERENCED) != 0)) {
pmap_clear_reference(VM_PAGE_TO_PHYS(m));
vm_page_activate(m);
m->flags &= ~PG_REFERENCED;
m = next;
continue;
}
@ -623,23 +705,15 @@ vm_pageout_scan()
*/
if ((next->flags & PG_INACTIVE) == 0)
goto rescan1;
} else if (pmap_is_referenced(VM_PAGE_TO_PHYS(m))) {
} else if ((m->flags & PG_REFERENCED) ||
pmap_is_referenced(VM_PAGE_TO_PHYS(m))) {
pmap_clear_reference(VM_PAGE_TO_PHYS(m));
m->flags &= ~PG_REFERENCED;
vm_page_activate(m);
}
m = next;
}
/*
* now check malloc area or swap processes out if we are in low
* memory conditions
*/
if (cnt.v_free_count <= cnt.v_free_min) {
/*
* swap out inactive processes
*/
swapout_threads();
}
/*
* Compute the page shortage. If we are still very low on memory
@ -673,13 +747,16 @@ vm_pageout_scan()
/*
* Don't deactivate pages that are busy.
*/
if ((m->flags & PG_BUSY) || (m->hold_count != 0)) {
if ((m->busy != 0) ||
(m->flags & PG_BUSY) || (m->hold_count != 0)) {
m = next;
continue;
}
if (pmap_is_referenced(VM_PAGE_TO_PHYS(m))) {
if ((m->flags & PG_REFERENCED) ||
pmap_is_referenced(VM_PAGE_TO_PHYS(m))) {
pmap_clear_reference(VM_PAGE_TO_PHYS(m));
m->flags &= ~PG_REFERENCED;
if (m->act_count < ACT_MAX)
m->act_count += ACT_ADVANCE;
TAILQ_REMOVE(&vm_page_queue_active, m, pageq);
@ -750,6 +827,7 @@ vm_pageout()
cnt.v_free_target = 2*cnt.v_free_min + cnt.v_free_reserved;
cnt.v_inactive_target = cnt.v_free_count / 12;
cnt.v_free_min += cnt.v_free_reserved;
vm_desired_cache_size = cnt.v_page_count / 3;
/* XXX does not really belong here */
if (vm_page_max_wired == 0)