Re: kmem accounting netperf data

From: Andrew Morton
Date: Wed Nov 21 2012 - 02:52:19 EST


On Fri, 16 Nov 2012 09:03:52 -0800 Greg Thelen <gthelen@xxxxxxxxxx> wrote:

> We ran some netperf comparisons measuring the overhead of enabling
> CONFIG_MEMCG_KMEM with a kmem limit. Short answer: no regression seen.
>
> This is a multiple machine (client,server) netperf test. Both client
> and server machines were running the same kernel with the same
> configuration.
>
> A baseline run (with CONFIG_MEMCG_KMEM unset) was compared with a full
> featured run (CONFIG_MEMCG_KMEM=y and a kmem limit large enough not to
> put additional pressure on the workload). We saw no noticeable
> regression running:
> - TCP_CRR efficiency, latency
> - TCP_RR latency, rate
> - TCP_STREAM efficiency, throughput
> - UDP_RR efficiency, latency
> The tests were run with a varying number of concurrent connections
> (between 1 and 200).
>
> The source came from one of Glauber's branches
> (git://git.kernel.org/pub/scm/linux/kernel/git/glommer/memcg
> kmemcg-slab):
> commit 70506dcf756aaafd92f4a34752d6b8d8ff4ed360
> Author: Glauber Costa <glommer@xxxxxxxxxxxxx>
> Date: Thu Aug 16 17:16:21 2012 +0400
>
> Add slab-specific documentation about the kmem controller
>
> It's not the latest source, but I figured the data might still be
> useful.

Let's cc the netdev guys, who will be pleased to hear that we didn't
break their stuff for once ;)

Thanks for testing - it was a concern.
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