linux-kernel - Re: mmap vs fs cache

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Message-ID: <20130308084246.GA4411@shutemov.name>
Date:	Fri, 8 Mar 2013 10:42:46 +0200
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Howard Chu <hyc@...as.com>
Cc:	Johannes Weiner <hannes@...xchg.org>, Jan Kara <jack@...e.cz>,
	linux-kernel <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: mmap vs fs cache

On Thu, Mar 07, 2013 at 11:46:39PM -0800, Howard Chu wrote:
> You're misreading the information then. slapd is doing no caching of
> its own, its RSS and SHR memory size are both the same. All it is
> using is the mmap, nothing else. The RSS == SHR == FS cache, up to
> 16GB. RSS is always == SHR, but above 16GB they grow more slowly
> than the FS cache.

It only means, that some pages got unmapped from your process. It can
happned, for instance, due page migration. There's nothing worry about: it
will be mapped back on next page fault to the page and it's only minor
page fault since the page is in pagecache anyway.

-- 
 Kirill A. Shutemov
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