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From: Michal Hocko <mhocko@suse.cz>
To: Matthias Wirth <matthias.wirth@gmail.com>
Cc: Lukas Senger <lukas@fridolin.com>,
	Matthew Wilcox <matthew@wil.cx>, Jeff Layton <jlayton@redhat.com>,
	"J. Bruce Fields" <bfields@fieldses.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Rik van Riel <riel@redhat.com>, Lisa Du <cldu@marvell.com>,
	Paul Mackerras <paulus@samba.org>,
	Sasha Levin <sasha.levin@oracle.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Fengguang Wu <fengguang.wu@intel.com>,
	Shaohua Li <shli@kernel.org>,
	Alexey Kardashevskiy <aik@ozlabs.ru>,
	Minchan Kim <minchan@kernel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Steven Whitehouse <swhiteho@redhat.com>,
	Mel Gorman <mgorman@suse.de>,
	Cody P Schafer <cody@linux.vnet.ibm.com>,
	Jiang Liu <liuj97@gmail.com>,
	David Rientjes <rientjes@google.com>,
	"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
Subject: Re: [PATCH] mm: implement POSIX_FADV_NOREUSE
Date: Tue, 11 Mar 2014 15:06:55 +0100	[thread overview]
Message-ID: <20140311140655.GD28292@dhcp22.suse.cz> (raw)
In-Reply-To: <1394533550-18485-1-git-send-email-matthias.wirth@gmail.com>

On Tue 11-03-14 11:25:41, Matthias Wirth wrote:
> Backups, logrotation and indexers don't need files they read to remain
> in the page cache. Their pages can be reclaimed early and should not
> displace useful pages. POSIX specifices the POSIX_FADV_NOREUSE flag for
> these use cases but it's currently a noop.

Why don't you use POSIX_FADV_DONTNEED when you no longer use those
pages? E.g. on close()?

> In our implementation pages marked with the NoReuse flag are added to
> the tail of the LRU list the first time they are read. Therefore they
> are the first to be reclaimed.

page flags are really scarce and I am not sure this is the best usage of
the few remaining slots.

> We needed to add flags to the file and page structs in order to pass
> down the hint to the actual call to list_add.
> 
> Signed-off-by: Matthias Wirth <matthias.wirth@gmail.com>
> Signed-off-by: Lukas Senger <lukas@fridolin.com>
[...]
-- 
Michal Hocko
SUSE Labs

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  reply	other threads:[~2014-03-11 14:06 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-11 10:25 [PATCH] mm: implement POSIX_FADV_NOREUSE Matthias Wirth
2014-03-11 14:06 ` Michal Hocko [this message]
2014-03-11 15:24   ` Dave Hansen
2014-03-11 21:27     ` Andrew Morton
2014-03-12 11:59       ` Lukas Senger
2014-03-12 14:46         ` Michal Hocko
2014-03-12 16:05         ` Dave Hansen
2014-03-13 12:40           ` Lukas Senger
2014-03-13 18:43 ` [PATCHv2] " Matthias Wirth
2014-03-13 20:01   ` Andrew Morton
2014-03-14 12:34     ` Lukas Senger
2014-03-14 15:52 ` [PATCHv3] " Matthias Wirth
2014-03-18 15:14   ` Michal Hocko

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