Memory controller improve user interface

[net-next-2.6.git] / Documentation / controllers / memory.txt

diff --git a/Documentation/controllers/memory.txt b/Documentation/controllers/memory.txt
index 7e27baacca7bc514bac1687828cea71ec2f28c72..61df8f81c80369138aff22b88e600c6a6c6b87b6 100644 (file)
--- a/Documentation/controllers/memory.txt
+++ b/Documentation/controllers/memory.txt
@@ -165,11 +165,30 @@ c. Enable CONFIG_CGROUP_MEM_CONT
 
 Since now we're in the 0 cgroup,
 We can alter the memory limit:
-# echo -n 6000 > /cgroups/0/memory.limit
+# echo -n 4M > /cgroups/0/memory.limit_in_bytes
+
+NOTE: We can use a suffix (k, K, m, M, g or G) to indicate values in kilo,
+mega or gigabytes.
+
+# cat /cgroups/0/memory.limit_in_bytes
+4194304 Bytes
+
+NOTE: The interface has now changed to display the usage in bytes
+instead of pages
 
 We can check the usage:
-# cat /cgroups/0/memory.usage
-25
+# cat /cgroups/0/memory.usage_in_bytes
+1216512 Bytes
+
+A successful write to this file does not guarantee a successful set of
+this limit to the value written into the file.  This can be due to a
+number of factors, such as rounding up to page boundaries or the total
+availability of memory on the system.  The user is required to re-read
+this file after a write to guarantee the value committed by the kernel.
+
+# echo -n 1 > memory.limit_in_bytes
+# cat memory.limit_in_bytes
+4096 Bytes
 
 The memory.failcnt field gives the number of times that the cgroup limit was
 exceeded.
@@ -206,8 +225,8 @@ cgroup might have some charge associated with it, even though all
 tasks have migrated away from it. If some pages are still left, after following
 the steps listed in sections 4.1 and 4.2, check the Swap Cache usage in
 /proc/meminfo to see if the Swap Cache usage is showing up in the
-cgroups memory.usage counter. A simple test of swapoff -a and swapon -a
-should free any pending Swap Cache usage.
+cgroups memory.usage_in_bytes counter. A simple test of swapoff -a and
+swapon -a should free any pending Swap Cache usage.
 
 4.4 Choosing what to account  -- Page Cache (unmapped) vs RSS (mapped)?