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-rw-r--r--Documentation/filesystems/proc.txt17
-rw-r--r--Documentation/sysctl/vm.txt3
2 files changed, 19 insertions, 1 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index d477356..a4dcf42 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -1302,6 +1302,23 @@ VM has token based thrashing control mechanism and uses the token to prevent
unnecessary page faults in thrashing situation. The unit of the value is
second. The value would be useful to tune thrashing behavior.
+drop_caches
+-----------
+
+Writing to this will cause the kernel to drop clean caches, dentries and
+inodes from memory, causing that memory to become free.
+
+To free pagecache:
+ echo 1 > /proc/sys/vm/drop_caches
+To free dentries and inodes:
+ echo 2 > /proc/sys/vm/drop_caches
+To free pagecache, dentries and inodes:
+ echo 3 > /proc/sys/vm/drop_caches
+
+As this is a non-destructive operation and dirty objects are not freeable, the
+user should run `sync' first.
+
+
2.5 /proc/sys/dev - Device specific parameters
----------------------------------------------
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 2f1aae3..89ba1a4 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -26,12 +26,13 @@ Currently, these files are in /proc/sys/vm:
- min_free_kbytes
- laptop_mode
- block_dump
+- drop-caches
==============================================================
dirty_ratio, dirty_background_ratio, dirty_expire_centisecs,
dirty_writeback_centisecs, vfs_cache_pressure, laptop_mode,
-block_dump, swap_token_timeout:
+block_dump, swap_token_timeout, drop-caches:
See Documentation/filesystems/proc.txt
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