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authorJerome Marchand <jmarchan@redhat.com>2014-01-21 18:49:14 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-21 19:19:44 -0500
commit49f0ce5f92321cdcf741e35f385669a421013cb7 (patch)
treed41c5a2283b32be69840cb8722ffd8cd8c38a1b0 /Documentation/vm
parentaec6a8889a98a0cd58357cd0937a25189908f191 (diff)
mm: add overcommit_kbytes sysctl variable
Some applications that run on HPC clusters are designed around the availability of RAM and the overcommit ratio is fine tuned to get the maximum usage of memory without swapping. With growing memory, the 1%-of-all-RAM grain provided by overcommit_ratio has become too coarse for these workload (on a 2TB machine it represents no less than 20GB). This patch adds the new overcommit_kbytes sysctl variable that allow a much finer grain. [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: fix nommu build] Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> 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/overcommit-accounting7
1 files changed, 4 insertions, 3 deletions
diff --git a/Documentation/vm/overcommit-accounting b/Documentation/vm/overcommit-accounting
index 8eaa2fc4b8fa..cbfaaa674118 100644
--- a/Documentation/vm/overcommit-accounting
+++ b/Documentation/vm/overcommit-accounting
@@ -14,8 +14,8 @@ The Linux kernel supports the following overcommit handling modes
14 14
152 - Don't overcommit. The total address space commit 152 - Don't overcommit. The total address space commit
16 for the system is not permitted to exceed swap + a 16 for the system is not permitted to exceed swap + a
17 configurable percentage (default is 50) of physical RAM. 17 configurable amount (default is 50%) of physical RAM.
18 Depending on the percentage you use, in most situations 18 Depending on the amount you use, in most situations
19 this means a process will not be killed while accessing 19 this means a process will not be killed while accessing
20 pages but will receive errors on memory allocation as 20 pages but will receive errors on memory allocation as
21 appropriate. 21 appropriate.
@@ -26,7 +26,8 @@ The Linux kernel supports the following overcommit handling modes
26 26
27The overcommit policy is set via the sysctl `vm.overcommit_memory'. 27The overcommit policy is set via the sysctl `vm.overcommit_memory'.
28 28
29The overcommit percentage is set via `vm.overcommit_ratio'. 29The overcommit amount can be set via `vm.overcommit_ratio' (percentage)
30or `vm.overcommit_kbytes' (absolute value).
30 31
31The current overcommit limit and amount committed are viewable in 32The current overcommit limit and amount committed are viewable in
32/proc/meminfo as CommitLimit and Committed_AS respectively. 33/proc/meminfo as CommitLimit and Committed_AS respectively.