[PATCH] zone_reclaim: dynamic slab reclaim

[pandora-kernel.git] / Documentation / sysctl / vm.txt

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 7cee902..20d0d79 100644 (file)
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -29,6 +29,7 @@ Currently, these files are in /proc/sys/vm:
 - drop-caches
 - zone_reclaim_mode
 - min_unmapped_ratio
+- min_slab_ratio
 - panic_on_oom
 
 ==============================================================
@@ -138,7 +139,6 @@ This is value ORed together of
 1      = Zone reclaim on
 2      = Zone reclaim writes dirty pages out
 4      = Zone reclaim swaps pages
-8      = Also do a global slab reclaim pass
 
 zone_reclaim_mode is set during bootup to 1 if it is determined that pages
 from remote zones will cause a measurable performance reduction. The
@@ -162,18 +162,13 @@ Allowing regular swap effectively restricts allocations to the local
 node unless explicitly overridden by memory policies or cpuset
 configurations.
 
-It may be advisable to allow slab reclaim if the system makes heavy
-use of files and builds up large slab caches. However, the slab
-shrink operation is global, may take a long time and free slabs
-in all nodes of the system.
-
 =============================================================
 
 min_unmapped_ratio:
 
 This is available only on NUMA kernels.
 
-A percentage of the file backed pages in each zone.  Zone reclaim will only
+A percentage of the total pages in each zone.  Zone reclaim will only
 occur if more than this percentage of pages are file backed and unmapped.
 This is to insure that a minimal amount of local pages is still available for
 file I/O even if the node is overallocated.
@@ -182,6 +177,24 @@ The default is 1 percent.
 
 =============================================================
 
+min_slab_ratio:
+
+This is available only on NUMA kernels.
+
+A percentage of the total pages in each zone.  On Zone reclaim
+(fallback from the local zone occurs) slabs will be reclaimed if more
+than this percentage of pages in a zone are reclaimable slab pages.
+This insures that the slab growth stays under control even in NUMA
+systems that rarely perform global reclaim.
+
+The default is 5 percent.
+
+Note that slab reclaim is triggered in a per zone / node fashion.
+The process of reclaiming slab memory is currently not node specific
+and may not be fast.
+
+=============================================================
+
 panic_on_oom
 
 This enables or disables panic on out-of-memory feature.  If this is set to 1,