There are two places where we reclaim free pages, but we never
update the all_unreclaimable flag for the relevant zone.
This patch helped reduce the frequency of oom-kills under high load
for us a while back, and we've been carrying it since.
I posted this a few months back and from what I recall it didn't
get a great deal of interest.
Signed-off-by: Dave Jones <[email protected]>
--- linux-2.6/mm/filemap.c~ 2005-12-10 01:47:15.000000000 -0500
+++ linux-2.6/mm/filemap.c 2005-12-10 01:47:46.000000000 -0500
@@ -471,11 +471,18 @@ EXPORT_SYMBOL(unlock_page);
*/
void end_page_writeback(struct page *page)
{
+ struct zone *zone = page_zone(page);
if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
if (!test_clear_page_writeback(page))
BUG();
}
smp_mb__after_clear_bit();
+ if (zone->all_unreclaimable) {
+ spin_lock(&zone->lock);
+ zone->all_unreclaimable = 0;
+ zone->pages_scanned = 0;
+ spin_unlock(&zone->lock);
+ }
wake_up_page(page, PG_writeback);
}
EXPORT_SYMBOL(end_page_writeback);
--- linux-2.6/mm/page_alloc.c~ 2006-01-09 13:40:03.000000000 -0500
+++ linux-2.6/mm/page_alloc.c 2006-01-09 13:40:50.000000000 -0500
@@ -722,6 +722,11 @@ static void fastcall free_hot_cold_page(
if (pcp->count >= pcp->high) {
free_pages_bulk(zone, pcp->batch, &pcp->list, 0);
pcp->count -= pcp->batch;
+ } else if (zone->all_unreclaimable) {
+ spin_lock(&zone->lock);
+ zone->all_unreclaimable = 0;
+ zone->pages_scanned = 0;
+ spin_unlock(&zone->lock);
}
local_irq_restore(flags);
put_cpu();
--
http://www.codemonkey.org.uk
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