From: Dave Hansen <dave.hansen@linux.intel.com>
To: Michal Hocko <mhocko@suse.cz>, 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>,
Zhang Yanfei <zhangyanfei@cn.fujitsu.com>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
Lukas Czerner <lczerner@redhat.com>,
Damien Ramonda <damien.ramonda@intel.com>,
Mark Rutland <mark.rutland@arm.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH] mm: implement POSIX_FADV_NOREUSE
Date: Tue, 11 Mar 2014 08:24:42 -0700 [thread overview]
Message-ID: <531F2ABA.6060804@linux.intel.com> (raw)
In-Reply-To: <20140311140655.GD28292@dhcp22.suse.cz>
On 03/11/2014 07:06 AM, Michal Hocko wrote:
>> > 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.
Yeah, especially since the use so so transient. I can see why using a
flag is nice for a quick prototype, but this is a far cry from needing
one. :) You might be able to reuse a bit like PageReadahead. You could
probably also use a bit in the page pointer of the lruvec, or even have
a percpu variable that stores a pointer to the 'struct page' you want to
mark as NOREUSE.
This also looks to ignore the reuse flag for existing pages. Have you
thought about what the semantics should be there?
Also, *should* readahead pages really have this flag set? If a very
important page gets brought in via readahead, doesn't this put it at a
disadvantage for getting aged out?
--
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next prev parent reply other threads:[~2014-03-11 15:34 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
2014-03-11 15:24 ` Dave Hansen [this message]
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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