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-rw-r--r--Documentation/sysctl/vm.txt27
1 files changed, 20 insertions, 7 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 7cee90223d3a..20d0d797f539 100644
--- 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,