linux-kernel - Re: [patch 1/3] mm: embed the memcg pointer directly into struct page

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Message-ID: <20141103210607.GA24091@node.dhcp.inet.fi>
Date:	Mon, 3 Nov 2014 23:06:07 +0200
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Hocko <mhocko@...e.cz>,
	Vladimir Davydov <vdavydov@...allels.com>,
	Tejun Heo <tj@...nel.org>, David Miller <davem@...emloft.net>,
	linux-mm@...ck.org, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 1/3] mm: embed the memcg pointer directly into struct page

On Sat, Nov 01, 2014 at 11:15:54PM -0400, Johannes Weiner wrote:
> Memory cgroups used to have 5 per-page pointers.  To allow users to
> disable that amount of overhead during runtime, those pointers were
> allocated in a separate array, with a translation layer between them
> and struct page.
> 
> There is now only one page pointer remaining: the memcg pointer, that
> indicates which cgroup the page is associated with when charged.  The
> complexity of runtime allocation and the runtime translation overhead
> is no longer justified to save that *potential* 0.19% of memory.

How much do you win by the change?

-- 
 Kirill A. Shutemov
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