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Subject[RFC][PATCH 0/8] RSS controller for containers
Here is set of patches that implements a *simple minded* RSS controller
for containers. It would be nice to split up the memory controller design
and implementation in phases

1. RSS control
2. Page Cache control (with split clean and dirty accounting/control)
3. mlock() control
4. Kernel accounting and control

The beancounter implementation follows a very similar approach. The split
up makes the design of the controller easier. RSS for example, can be tracked
per mm_struct. Page Cache could be tracked per inode, per thread
or per mm_struct (depending on what form is most suitable).

The definition of RSS was debated on lkml, please see

This patchset is a proof of concept implementation and the accounting can
be easily adapted to meet the definition of RSS as and when it is re-defined
or revisited. The changes required should be small.

The reclamation logic has been borrowed from Dave Hansen's challenged
memory controller and from shrink_all_memory(). The accounting was inspired
from Rohit Seth's container patches.

The good

No additional pointers required in struct page.
There is also a lot of scope for code reuse in tracking the rss of a process
(this reuse is yet to be exploited).

The not so good
The patches contain a lot of debugging code.

Applying the patches
This patchset has been developed on top of 2.6.19-rc2 with the latest
containers patch applied.

To run and test this patch, additional fixes are required.

Please see


To test the series, here's what you need to do

0. Get the latest containers patches against 2.6.19-rc2
1. Apply all the fixes
2. Apply these patches
3. Build the kernel and mount the container filesystem
mount -t container container /container

4. Disable cpuset's (to simply assignment of tasks to resource groups)

cd /container
echo 0 > cpuset_enabled

5. Add the current task to a new group

mkdir /container/a
echo $$ > tasks
cat memctlr_stats

6. Set limits

echo "res=memctlr,max_shares=10" > memctlr_shares

7. Spin the system, hang it, revolve it, crash it!!
8. Please provide feedback, both code review and any thing else that
can be useful for further development

Kernbench was run on these patches and it did not show any significant
overhead in the tests.


Balbir Singh,
Linux Technology Center,
IBM Software Labs
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