Date: Wed, 11 Nov 2015 19:07:19 +0300
From: Vladimir Davydov <vdavydov@virtuozzo.com>
To: Tejun Heo <tj@kernel.org>
CC: Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@kernel.org>,
        Greg Thelen <gthelen@google.com>, Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>, <linux-mm@kvack.org>,
        <cgroups@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 4/6] slab: add SLAB_ACCOUNT flag
Message-ID: <20151111160719.GX31308@esperanza>
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On Wed, Nov 11, 2015 at 10:54:50AM -0500, Tejun Heo wrote:
> Hello,
> 
> On Tue, Nov 10, 2015 at 09:54:01PM +0300, Vladimir Davydov wrote:
> > > Am I correct in thinking that we should eventually be able to removed
> > > __GFP_ACCOUNT and that only caches explicitly marked with SLAB_ACCOUNT
> > > would need to be handled by kmemcg?
> > 
> > Don't think so, because sometimes we want to account kmalloc.
> 
> I'm kinda skeptical about that because if those allocations are
> occassional by nature, we don't care and if there can be a huge number
> of them, splitting them into a separate cache makes sense.  I think it
> makes sense to pin down exactly which caches are memcg managed.  That
> has the potential to simplify the involved code path and shave off a
> small bit of hot path overhead.

What about external_name allocation in __d_alloc? Is it occasional?
Depends on the workload I guess. Can we create a separate cache for it?
No, because its size is variable. There are other things like that, e.g.
pipe_buffer array.

Thanks,
Vladimir
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