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SubjectRe: [PATCH] meminfo: show /proc/meminfo base on container's memcg
On Thu, 31 May 2012, Kamezawa Hiroyuki wrote:

> > It's not just a memcg issue, it would also be a cpusets issue.
>
> I think you can add cpuset.meminfo.
>

It's simple to find the same information by reading the per-node meminfo
files in sysfs for each of the allowed cpuset mems. This is why this
approach has been nacked in the past, specifically by Paul Jackson when he
implemented cpusets.

The bottomline is that /proc/meminfo is one of many global resource state
interfaces and doesn't imply that every thread has access to the full
resources. It never has. It's very simple for another thread to consume
a large amount of memory as soon as your read() of /proc/meminfo completes
and then that information is completely bogus. We also don't want to
virtualize every single global resource state interface, it would be never
ending.

Applications that administer memory cgroups or cpusets can get this
information very easily, each application within those memory cgroups or
cpusets does not need it and should not rely on it: it provides no
guarantee about future usage nor notifies the application when the amount
of free memory changes.


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