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Date: Mon, 11 Mar 2013 12:52:20 +0100
From: Jan Kara <jack@suse.cz>
Subject: Re: mmap vs fs cache
Message-ID: <20130311115220.GB29799@quack.suse.cz>
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To: Phillip Susi <psusi@ubuntu.com>
Cc: Howard Chu <hyc@symas.com>, Chris Friesen <chris.friesen@genband.com>, "Kirill A. Shutemov" <kirill@shutemov.name>, Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>, linux-kernel <linux-kernel@vger.kernel.org>, linux-mm@kvack.org

On Fri 08-03-13 20:22:19, Phillip Susi wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> 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.
  Why do you think so? AFAICS it is implemented by setting VM_RAND_READ
flag in the VMA and do_async_mmap_readahead() and do_sync_mmap_readahead()
check for the flag and don't do anything if it is set...

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

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