Date: Wed, 1 Apr 2015 18:17:17 +0300
From: Vladimir Davydov <vdavydov@parallels.com>
To: Jonathan Corbet <corbet@lwn.net>
CC: Andrew Morton <akpm@linux-foundation.org>, <linux-mm@kvack.org>,
        <cgroups@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Documentation/memcg: update memcg/kmem status
Message-ID: <20150401151717.GE21839@esperanza>
References: <1427898636-4505-1-git-send-email-vdavydov@parallels.com>
 <20150401164431.1e88220a@lwn.net>
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On Wed, Apr 01, 2015 at 04:44:31PM +0200, Jonathan Corbet wrote:
> On Wed, 1 Apr 2015 17:30:36 +0300
> Vladimir Davydov <vdavydov@parallels.com> wrote:
> 
> > Memcg/kmem reclaim support has been finally merged. Reflect this in the
> > documentation.
> 
> So the text you've removed says not to select kmem support "unless for
> development purposes."  Do we now believe that this feature is ready for
> use in a production setting?  If the answer is "yes," I'd be happy to
> take this through the docs tree.

I added this warning because of the following issues, which made
memcg/kmem useless:

 - no reclaim support
 - lack of memcg slab caches auto destruction
 - several obvious races/bugs

They are all fixed now, so I think the answer is yes, it can be used in
production. There might be bugs that I am not aware of, of course, but
It must be safe to compile it in anyway, because memcg/kmem accounting
is disabled by default and must be enabled explicitly at runtime by
writing to cgroup/memory.kmem.limit_in_bytes.

Thanks,
Vladimir
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