linux-kernel - Re: [PATCH] Documentation/memcg: update memcg/kmem status

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Message-ID: <20150404152934.2db95051@lwn.net>
Date:	Sat, 4 Apr 2015 15:29:34 +0200
From:	Jonathan Corbet <corbet@....net>
To:	Vladimir Davydov <vdavydov@...allels.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, <linux-mm@...ck.org>,
	<cgroups@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Documentation/memcg: update memcg/kmem status

On Wed, 1 Apr 2015 18:17:17 +0300
Vladimir Davydov <vdavydov@...allels.com> wrote:

> > 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.

So I believe you, but I'm still a bit nervous about taking this one
because I can't really judge whether we should be advising people to turn
on this feature at this point or not.  A well-placed ack or two would
help there; otherwise, Andrew, if you think it makes sense, you can just
grab it :)

Thanks,

jon
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