On Wed, Feb 29, 2012 at 9:09 AM, Glauber Costa [off-list ref] wrote:

On 02/28/2012 08:36 PM, Suleiman Souhlal wrote:

quoted

On Tue, Feb 28, 2012 at 5:34 AM, Glauber Costa[off-list ref]
 wrote:

quoted

On 02/27/2012 07:58 PM, Suleiman Souhlal wrote:

quoted

This config option dictates whether or not kernel memory in the
root cgroup should be accounted.

This may be useful in an environment where everything is supposed to be
in a cgroup and accounted for. Large amounts of kernel memory in the
root cgroup would indicate problems with memory isolation or accounting.

I don't like accounting this stuff to the root memory cgroup. This causes
overhead for everybody, including people who couldn't care less about
memcg.

If it were up to me, we would simply not account it, and end of story.

However, if this is terribly important for you, I think you need to at
least make it possible to enable it at runtime, and default it to
disabled.

Yes, that is why I made it a config option. If the config option is
disabled, that memory does not get accounted at all.

Doesn't work. In reality, most of the distributions enable those stuff if
there is the possibility that someone will end up using. So everybody gets
to pay the penalty.

quoted

Making it configurable at runtime is not ideal, because we would
prefer slab memory that was allocated before cgroups are created to
still be counted toward root.

Again: Why is that you really need it ? Accounting slab to the root cgroup
feels quite weird to me

Because, for us, having large amounts of unaccounted memory is a
"bug", and we would like to know when it happens.
Also, we want to know how much memory is actually available in the
machine for jobs (sum of(accounted memory in containers) - unaccounted
kernel memory).

That said, I will drop this patch from the series for now.

-- Suleiman

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