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authorHugh Dickins <hughd@google.com>2013-02-22 16:36:03 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-23 17:50:23 -0800
commit8fdb3dbf02335d96bf170321381522709ba63a0c (patch)
tree5c81a212ef5960298ec4d284640c38f707f5dad6 /Documentation/vm
parent49cd0a5c290f99deca3463d16c3c1c7240107889 (diff)
downloadlinux-linaro-stable-8fdb3dbf02335d96bf170321381522709ba63a0c.tar.gz
ksm: add some comments
Added slightly more detail to the Documentation of merge_across_nodes, a few comments in areas indicated by review, and renamed get_ksm_page()'s argument from "locked" to "lock_it". No functional change. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Petr Holasek <pholasek@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/vm')
-rw-r--r--Documentation/vm/ksm.txt16
1 files changed, 12 insertions, 4 deletions
diff --git a/Documentation/vm/ksm.txt b/Documentation/vm/ksm.txt
index 25cc89ba811b..f34a8ee6f860 100644
--- a/Documentation/vm/ksm.txt
+++ b/Documentation/vm/ksm.txt
@@ -60,10 +60,18 @@ sleep_millisecs - how many milliseconds ksmd should sleep before next scan
merge_across_nodes - specifies if pages from different numa nodes can be merged.
When set to 0, ksm merges only pages which physically
- reside in the memory area of same NUMA node. It brings
- lower latency to access to shared page. Value can be
- changed only when there is no ksm shared pages in system.
- Default: 1
+ reside in the memory area of same NUMA node. That brings
+ lower latency to access of shared pages. Systems with more
+ nodes, at significant NUMA distances, are likely to benefit
+ from the lower latency of setting 0. Smaller systems, which
+ need to minimize memory usage, are likely to benefit from
+ the greater sharing of setting 1 (default). You may wish to
+ compare how your system performs under each setting, before
+ deciding on which to use. merge_across_nodes setting can be
+ changed only when there are no ksm shared pages in system:
+ set run 2 to unmerge pages first, then to 1 after changing
+ merge_across_nodes, to remerge according to the new setting.
+ Default: 1 (merging across nodes as in earlier releases)
run - set 0 to stop ksmd from running but keep merged pages,
set 1 to run ksmd e.g. "echo 1 > /sys/kernel/mm/ksm/run",