[PATCH] zone_reclaim: configurable off node allocation period.

Currently the zone_reclaim code has a fixed window of 30 seconds of off node
allocations should a local zone have no unused pagecache pages left.  Reclaim
will be attempted again after this timeout period to avoid repeated useless
scans for memory.  This is also useful to established sufficiently large off
node allocation chunks to relieve the local node.

It may be beneficial to adjust that time period for some special situations.
For example if memory use was exceeding node capacity one may want to give up
for longer periods of time.  If memory spikes intermittendly then one may want
to shorten the time period to reduce the number of off node allocations.

This patch allows just that....

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 3 insertions, 1 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 4a99e4a7fbf3..e53fef7051e6 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -178,6 +178,7 @@ extern int vm_swappiness;
 
 #ifdef CONFIG_NUMA
 extern int zone_reclaim_mode;
+extern int zone_reclaim_interval;
 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 #else
 #define zone_reclaim_mode 0
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 8352a7ce5895..32a4139c4ad8 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -182,7 +182,8 @@ enum
         VM_SWAP_TOKEN_TIMEOUT=28, /* default time for token time out */
         VM_DROP_PAGECACHE=29,   /* int: nuke lots of pagecache */
         VM_PERCPU_PAGELIST_FRACTION=30,/* int: fraction of pages in each percpu_pagelist */
-        VM_ZONE_RECLAIM_MODE=31,/* reclaim local zone memory before going off node */
+        VM_ZONE_RECLAIM_MODE=31, /* reclaim local zone memory before going off node */
+        VM_ZONE_RECLAIM_INTERVAL=32, /* time period to wait after reclaim failure */
 };