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authorRik van Riel <riel@redhat.com>2012-03-21 16:33:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 17:54:56 -0700
commit7be62de99adcab4449d416977b4274985c5fe023 (patch)
tree20ae021ec9811ad730e6a17a3530d3aa6b5027d0 /mm/vmscan.c
parentfe2c2a106663130a5ab45cb0e3414b52df2fff0c (diff)
vmscan: kswapd carefully call compaction
With CONFIG_COMPACTION enabled, kswapd does not try to free contiguous free pages, even when it is woken for a higher order request. This could be bad for eg. jumbo frame network allocations, which are done from interrupt context and cannot compact memory themselves. Higher than before allocation failure rates in the network receive path have been observed in kernels with compaction enabled. Teach kswapd to defragment the memory zones in a node, but only if required and compaction is not deferred in a zone. [akpm@linux-foundation.org: reduce scope of zones_need_compaction] Signed-off-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Hillf Danton <dhillf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index d7dad2a4e69c..b2b4c4a0ada2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2919,6 +2919,8 @@ out:
* and it is potentially going to sleep here.
*/
if (order) {
+ int zones_need_compaction = 1;
+
for (i = 0; i <= end_zone; i++) {
struct zone *zone = pgdat->node_zones + i;
@@ -2939,9 +2941,17 @@ out:
goto loop_again;
}
+ /* Check if the memory needs to be defragmented. */
+ if (zone_watermark_ok(zone, order,
+ low_wmark_pages(zone), *classzone_idx, 0))
+ zones_need_compaction = 0;
+
/* If balanced, clear the congested flag */
zone_clear_flag(zone, ZONE_CONGESTED);
}
+
+ if (zones_need_compaction)
+ compact_pgdat(pgdat, order);
}
/*