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-rw-r--r--Documentation/vm/overcommit-accounting8
1 files changed, 7 insertions, 1 deletions
diff --git a/Documentation/vm/overcommit-accounting b/Documentation/vm/overcommit-accounting
index 706d7ed9d8d..8eaa2fc4b8f 100644
--- a/Documentation/vm/overcommit-accounting
+++ b/Documentation/vm/overcommit-accounting
@@ -8,7 +8,9 @@ The Linux kernel supports the following overcommit handling modes
default.
1 - Always overcommit. Appropriate for some scientific
- applications.
+ applications. Classic example is code using sparse arrays
+ and just relying on the virtual memory consisting almost
+ entirely of zero pages.
2 - Don't overcommit. The total address space commit
for the system is not permitted to exceed swap + a
@@ -18,6 +20,10 @@ The Linux kernel supports the following overcommit handling modes
pages but will receive errors on memory allocation as
appropriate.
+ Useful for applications that want to guarantee their
+ memory allocations will be available in the future
+ without having to initialize every page.
+
The overcommit policy is set via the sysctl `vm.overcommit_memory'.
The overcommit percentage is set via `vm.overcommit_ratio'.