kmem accounting netperf data

kmem accounting netperf data

[Greg Thelen]

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@parallels.com>
  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.

Re: kmem accounting netperf data

[Andrew Morton]

On Fri, 16 Nov 2012 09:03:52 -0800 Greg Thelen <gthelen@google.com> 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@parallels.com>
>   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.