Message-ID: <1345037397.2976.44.camel@dabdike.int.hansenpartnership.com>
Subject: Re: [PATCH v2 04/11] kmem accounting basic infrastructure
From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@parallels.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, cgroups@vger.kernel.org, devel@openvz.org,
        Johannes Weiner <hannes@cmpxchg.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        kamezawa.hiroyu@jp.fujitsu.com, Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Pekka Enberg <penberg@kernel.org>
Date: Wed, 15 Aug 2012 14:29:57 +0100
In-Reply-To: <20120815125555.GG23985@dhcp22.suse.cz>
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	 <20120814162144.GC6905@dhcp22.suse.cz> <502B6D03.1080804@parallels.com>
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On Wed, 2012-08-15 at 14:55 +0200, Michal Hocko wrote:
> On Wed 15-08-12 12:12:23, James Bottomley wrote:
> > On Wed, 2012-08-15 at 13:33 +0400, Glauber Costa wrote:
> > > > This can
> > > > be quite confusing.  I am still not sure whether we should mix the two
> > > > things together. If somebody wants to limit the kernel memory he has to
> > > > touch the other limit anyway.  Do you have a strong reason to mix the
> > > > user and kernel counters?
> > > 
> > > This is funny, because the first opposition I found to this work was
> > > "Why would anyone want to limit it separately?" =p
> > > 
> > > It seems that a quite common use case is to have a container with a
> > > unified view of "memory" that it can use the way he likes, be it with
> > > kernel memory, or user memory. I believe those people would be happy to
> > > just silently account kernel memory to user memory, or at the most have
> > > a switch to enable it.
> > > 
> > > What gets clear from this back and forth, is that there are people
> > > interested in both use cases.
> > 
> > Haven't we already had this discussion during the Prague get together?
> > We discussed the use cases and finally agreed to separate accounting for
> > k and then k+u mem because that satisfies both the Google and Parallels
> > cases.  No-one was overjoyed by k and k+u but no-one had a better
> > suggestion ... is there a better way of doing this that everyone can
> > agree to?
> > We do need to get this nailed down because it's the foundation of the
> > patch series.
> 
> There is a slot in MM/memcg minisum at KS so we have a slot to discuss
> this.

Sure, to get things moving, can you pre-prime us with what you're
thinking in this area so we can be prepared (and if it doesn't work,
tell you beforehand)?

Thanks,

James


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