Re: What can we do to get ready for memory controller merge in 2.6.25

[Balbir Singh <balbir@linux.vnet.ibm.com>]

Nick Piggin wrote:
> On Friday 30 November 2007 01:43, Balbir Singh wrote:
>> They say better strike when the iron is hot.
>>
>> Since we have so many people discussing the memory controller, I would
>> like to access the readiness of the memory controller for mainline
>> merge. Given that we have some time until the merge window, I'd like to
>> set aside some time (from my other work items) to work on the memory
>> controller, fix review comments and defects.
>>
>> In the past, we've received several useful comments from Rik Van Riel,
>> Lee Schermerhorn, Peter Zijlstra, Hugh Dickins, Nick Piggin, Paul Menage
>> and code contributions and bug fixes from Hugh Dickins, Pavel Emelianov,
>> Lee Schermerhorn, YAMAMOTO-San, Andrew Morton and KAMEZAWA-San. I
>> apologize if I missed out any other names or contributions
>>
>> At the VM-Summit we decided to try the current double LRU approach for
>> memory control. At this juncture in the space-time continuum, I seek
>> your support, feedback, comments and help to move the memory controller
> 
> Do you have any test cases, performance numbers, etc.? And also some
> results or even anecdotes of where this is going to be used would be
> interesting...
> 

Some test results were posted at

http://lkml.org/lkml/2007/8/17/69
http://lkml.org/lkml/2007/8/19/36
http://lwn.net/Articles/242554/

Some results for the RSS controller can be found in the OLS paper

https://ols2006.108.redhat.com/2007/Reprints/singh-Reprint.pdf

and at

http://lkml.org/lkml/2007/5/18/1

As far as test cases are concerned, I have a simple test case that I use
that allocates memory and touches all the allocated memory in a loop. I
can post that out if required. It uses various types of allocation

1. mmaped memory
2. anonymous memory
3. shared memory

I also run various benchmarks inside a control group, limited to 400 MB
of RAM.

One interesting that I noticed was that when I booted with mem=<some
memory> and created a container with the same <some value>. The swapout
test case ran much faster in the container (NOTE: This was prior to the
swap cache changes).

KAMEZAWA-San posted some test results on background reclaim and per zone
reclaim

http://forum.openvz.org/index.php?t=tree&th=4696&mid=23964&&rev=&reveal=

The simplest use cases that come to mind are

1. Memory control for containers/virtualization
2. Job Isolation


-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL