[RFC][PATCH][0/4] Memory controller (RSS Control)

[Balbir Singh <balbir@in.ibm.com>]

This patch applies on top of Paul Menage's container patches (V7) posted at

	http://lkml.org/lkml/2007/2/12/88

It implements a controller within the containers framework for limiting
memory usage (RSS usage).

The memory controller was discussed at length in the RFC posted to lkml
	http://lkml.org/lkml/2006/10/30/51

Steps to use the controller
--------------------------


0. Download the patches, apply the patches
1. Turn on CONFIG_CONTAINER_MEMCTLR in kernel config, build the kernel
   and boot into the new kernel
2. mount -t container container -o memctlr /<mount point>
3. cd /<mount point>
   optionally do (mkdir <directory>; cd <directory>) under /<mount point>
4. echo $$ > tasks (attaches the current shell to the container)
5. echo -n (limit value) > memctlr_limit
6. cat memctlr_usage
7. Run tasks, check the usage of the controller, reclaim behaviour
8. Report bugs, get bug fixes and iterate (goto step 0).

Advantages of the patchset
--------------------------

1. Zero overhead in struct page (struct page is not expanded)
2. Minimal changes to the core-mm code
3. Shared pages are not reclaimed unless all mappings belong to overlimit
   containers.
4. It can be used to debug drivers/applications/kernel components in a
   constrained memory environment (similar to mem=XXX option), except that
   several containers can be created simultaneously without rebooting and
   the limits can be changed. NOTE: There is no support for limiting
   kernel memory allocations and page cache control (presently).

Testing
-------
Ran kernbench and lmbench with containers enabled (container filesystem not
mounted), they seemed to run fine
Created containers, attached tasks to containers with lower limits than
the memory the tasks require (memory hog tests) and ran some basic tests on
them

TODO's and improvement areas
----------------------------
1. Come up with cool page replacement algorithms for containers
   (if possible without any changes to struct page)
2. Add page cache control
3. Add kernel memory allocator control
4. Extract benchmark numbers and overhead data

Comments & criticism are welcome.

Series
------
memctlr-setup.patch
memctlr-acct.patch
memctlr-reclaim-on-limit.patch
memctlr-doc.patch

-- 
	Warm Regards,
	Balbir Singh