lkml.org 
[lkml]   [2012]   [Sep]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC 2/4] memcg: make it suck faster
On Wed, Sep 26, 2012 at 12:53:21PM +0400, Glauber Costa wrote:
> On 09/26/2012 01:02 AM, Andrew Morton wrote:
> >> nomemcg : memcg compile disabled.
> >> > base : memcg enabled, patch not applied.
> >> > bypassed : memcg enabled, with patch applied.
> >> >
> >> > base bypassed
> >> > User 109.12 105.64
> >> > System 1646.84 1597.98
> >> > Elapsed 229.56 215.76
> >> >
> >> > nomemcg bypassed
> >> > User 104.35 105.64
> >> > System 1578.19 1597.98
> >> > Elapsed 212.33 215.76
> >> >
> >> > So as one can see, the difference between base and nomemcg in terms
> >> > of both system time and elapsed time is quite drastic, and consistent
> >> > with the figures shown by Mel Gorman in the Kernel summit. This is a
> >> > ~ 7 % drop in performance, just by having memcg enabled. memcg functions
> >> > appear heavily in the profiles, even if all tasks lives in the root
> >> > memcg.
> >> >
> >> > With bypassed kernel, we drop this down to 1.5 %, which starts to fall
> >> > in the acceptable range. More investigation is needed to see if we can
> >> > claim that last percent back, but I believe at last part of it should
> >> > be.
> > Well that's encouraging. I wonder how many users will actually benefit
> > from this - did I hear that major distros are now using memcg in some
> > system-infrastructure-style code?
> >
>
> If they do, they actually be come "users of memcg". This here is aimed
> at non-users of memcg, which given all the whining about it, it seems to
> be plenty.
>
> Also, I noticed, for instance, that libvirt is now creating memcg
> hierarchies for lxc and qemu as placeholders, before you actually create
> any vm or container.

This is mostly just lazyness on our part. There's no technical reason
why we can't delay creating our intermediate cgroups until we actually
have a VM ready to start, it was just simpler to create them when we
started the main daemon.


Daniel
--
|: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|


\
 
 \ /
  Last update: 2012-09-26 11:41    [W:0.053 / U:0.036 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site