Re: Swappiness vs. mmap() and interactive response

Elladan
2009-04-28T07:27:21Z

On Tue, Apr 28, 2009 at 03:52:29PM +0900, KOSAKI Motohiro wrote:
> Hi
>
> > 3. cache limitation of memcgroup solve this problem?
> >
> > I was unable to get this to work -- do you have some documentation handy?
>
> Do you have kernel source tarball?
> Documentation/cgroups/memory.txt explain usage kindly.

Thank you. My documentation was out of date.

I created a cgroup with limited memory and placed a copy command in it, and the
latency problem seems to essentially go away. However, I'm also a bit
suspicious that my test might have become invalid, since my IO performance
seems to have dropped somewhat too.

So, am I right in concluding that this more or less implicates bad page
replacement as the culprit? After I dropped vm caches and let my working set
re-form, the memory cgroup seems to be effective at keeping a large pool of
memory free from file pressure.