linux-kernel - Re: mmap vs fs cache

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Date:	Fri, 08 Mar 2013 20:22:19 -0500
From:	Phillip Susi <psusi@...ntu.com>
To:	Howard Chu <hyc@...as.com>
CC:	Chris Friesen <chris.friesen@...band.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	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

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On 03/08/2013 10:00 AM, Howard Chu wrote:
> Yes, that's what I was thinking. I added a 
> posix_madvise(..POSIX_MADV_RANDOM) but that had no effect on the
> test.

Yep, that's because it isn't implemented.

You might try MADV_WILLNEED to schedule it to be read in first.  I
believe that will only read in the requested page, without additional
readahead, and then when you fault on the page, it already has IO
scheduled, so the extra readahead will also be skipped.


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