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

From: Balbir Singh
Date: Thu Nov 29 2007 - 22:14:16 EST

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

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

and at

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

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
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