lkml.org 
[lkml]   [2013]   [Jun]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/2] mm: vmscan: Avoid direct reclaim scanning at maximum priority
Date
Page reclaim at priority 0 will scan the entire LRU as priority 0 is
considered to be a near OOM condition. Direct reclaim can reach this
priority while still making reclaim progress. This patch avoids
reclaiming at priority 0 unless no reclaim progress was made and
the page allocator would consider firing the OOM killer. The
user-visible impact is that direct reclaim will not easily reach
priority 0 and start swapping prematurely.

Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/vmscan.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index fe73724..65f2fbea 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2382,12 +2382,14 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
struct zone *zone;
unsigned long writeback_threshold;
bool aborted_reclaim;
+ int min_scan_priority = 1;

delayacct_freepages_start();

if (global_reclaim(sc))
count_vm_event(ALLOCSTALL);

+rescan:
do {
vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
sc->priority);
@@ -2442,7 +2444,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
WB_REASON_TRY_TO_FREE_PAGES);
sc->may_writepage = 1;
}
- } while (--sc->priority >= 0);
+ } while (--sc->priority >= min_scan_priority);

out:
delayacct_freepages_end();
@@ -2466,6 +2468,12 @@ out:
if (global_reclaim(sc) && !all_unreclaimable(zonelist, sc))
return 1;

+ /* If the page allocator is considering OOM, rescan at priority 0 */
+ if (min_scan_priority) {
+ min_scan_priority = 0;
+ goto rescan;
+ }
+
return 0;
}

--
1.8.1.4


\
 
 \ /
  Last update: 2013-06-26 15:21    [W:0.042 / U:0.280 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site