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-rw-r--r--Documentation/sysctl/vm.txt20
1 files changed, 20 insertions, 0 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 078701fdbd4d..f69895738357 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -53,6 +53,7 @@ Currently, these files are in /proc/sys/vm:
- percpu_pagelist_fraction
- stat_interval
- swappiness
+- user_reserve_kbytes
- vfs_cache_pressure
- zone_reclaim_mode
@@ -542,6 +543,7 @@ memory until it actually runs out.
When this flag is 2, the kernel uses a "never overcommit"
policy that attempts to prevent any overcommit of memory.
+Note that user_reserve_kbytes affects this policy.
This feature can be very useful because there are a lot of
programs that malloc() huge amounts of memory "just-in-case"
@@ -645,6 +647,24 @@ The default value is 60.
==============================================================
+- user_reserve_kbytes
+
+When overcommit_memory is set to 2, "never overommit" mode, reserve
+min(3% of current process size, user_reserve_kbytes) of free memory.
+This is intended to prevent a user from starting a single memory hogging
+process, such that they cannot recover (kill the hog).
+
+user_reserve_kbytes defaults to min(3% of the current process size, 128MB).
+
+If this is reduced to zero, then the user will be allowed to allocate
+all free memory with a single process, minus admin_reserve_kbytes.
+Any subsequent attempts to execute a command will result in
+"fork: Cannot allocate memory".
+
+Changing this takes effect whenever an application requests memory.
+
+==============================================================
+
vfs_cache_pressure
------------------