Messages in this thread Patch in this message | | | From | KOSAKI Motohiro <> | Subject | [PATCH 4/4] zone_reclaim_mode is always 0 by default | Date | Wed, 13 May 2009 12:08:12 +0900 (JST) |
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Subject: [PATCH] zone_reclaim_mode is always 0 by default
Current linux policy is, if the machine has large remote node distance, zone_reclaim_mode is enabled by default because we've be able to assume to large distance mean large server until recently.
Unfrotunately, recent modern x86 CPU (e.g. Core i7, Opeteron) have P2P transport memory controller. IOW it's NUMA from software view.
Some Core i7 machine has large remote node distance and zone_reclaim don't fit desktop and small file server. it cause performance degression.
Thus, zone_reclaim == 0 is better by default. sorry, HPC gusy. you need to turn zone_reclaim_mode on manually now.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Rik van Riel <riel@redhat.com> --- mm/page_alloc.c | 7 ------- 1 file changed, 7 deletions(-)
Index: b/mm/page_alloc.c =================================================================== --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2494,13 +2494,6 @@ static void build_zonelists(pg_data_t *p int distance = node_distance(local_node, node); /* - * If another node is sufficiently far away then it is better - * to reclaim pages in a zone before going off node. - */ - if (distance > RECLAIM_DISTANCE) - zone_reclaim_mode = 1; - - /* * We don't want to pressure a particular node. * So adding penalty to the first node in same * distance group to make it round-robin.
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