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From: Tejun Heo <tj@kernel.org>
To: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Greg Thelen <gthelen@google.com>,
	linux-mm@kvack.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/5] memcg/kmem: switch to white list policy
Date: Mon, 9 Nov 2015 15:30:53 -0500	[thread overview]
Message-ID: <20151109203053.GD28507@mtj.duckdns.org> (raw)
In-Reply-To: <20151109201218.GP31308@esperanza>

Hello, Vladimir.

On Mon, Nov 09, 2015 at 11:12:18PM +0300, Vladimir Davydov wrote:
> Because we won't be able to distinguish kmem_cache_alloc calls that
> should be accounted from those that shouldn't. The problem is if two
> caches
> 
> 	A = kmem_cache_create(...)
> 
> and
> 
> 	B = kmem_cache_create(...)
> 
> happen to be merged, A and B will point to the same kmem_cache struct.
> As a result, there is no way to distinguish
> 
> 	kmem_cache_alloc(A)
> 
> which we want to account from
> 
> 	kmem_cache_alloc(B)
> 
> which we don't.

Hmm.... can't we simply merge among !SLAB_ACCOUNT and SLAB_ACCOUNT
kmem_caches within themselves?  I don't think we'd be losing anything
by restricting merge at that level.  For anything to be tagged
SLAB_ACCOUNT, it has to have a potential to grow enormous after all.

Thanks.

-- 
tejun

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  reply	other threads:[~2015-11-09 20:30 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-07 20:07 [PATCH 0/5] memcg/kmem: switch to white list policy Vladimir Davydov
2015-11-07 20:07 ` [PATCH 1/5] Revert "kernfs: do not account ino_ida allocations to memcg" Vladimir Davydov
2015-11-07 20:07 ` [PATCH 2/5] Revert "gfp: add __GFP_NOACCOUNT" Vladimir Davydov
2015-11-07 20:07 ` [PATCH 3/5] memcg: only account kmem allocations marked as __GFP_ACCOUNT Vladimir Davydov
2015-11-07 20:07 ` [PATCH 4/5] vmalloc: allow to account vmalloc to memcg Vladimir Davydov
2015-11-07 20:07 ` [PATCH 5/5] Account certain kmem allocations " Vladimir Davydov
2015-11-09 14:39   ` Michal Hocko
2015-11-10  8:07     ` Vladimir Davydov
2015-11-10 13:23       ` Michal Hocko
2015-11-09 14:08 ` [PATCH 0/5] memcg/kmem: switch to white list policy Michal Hocko
2015-11-09 16:45   ` Johannes Weiner
2015-11-09 18:28   ` Vladimir Davydov
2015-11-09 18:54     ` Tejun Heo
2015-11-09 19:27       ` Vladimir Davydov
2015-11-09 19:32         ` Tejun Heo
2015-11-09 20:12           ` Vladimir Davydov
2015-11-09 20:30             ` Tejun Heo [this message]
2015-11-10  7:49               ` Vladimir Davydov
2015-11-11  8:12     ` Michal Hocko

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