From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Subject: Re: [PATCH 2/8] readahead: make default readahead size a kernel parameter
Date: Wed, 30 Nov 2011 14:04:11 +0100
Message-ID: <4ED629CB.401@linux.vnet.ibm.com>
References: <20111121091819.394895091@intel.com> <20111121093846.251104145@intel.com> <20111121100137.GC5084@infradead.org> <20111121113540.GB8895@localhost> <20111124222822.GG29519@quack.suse.cz> <20111125003633.GP2386@dastard> <20111128023922.GA2141@localhost>
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Cc: Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.cz>,
        Christoph Hellwig <hch@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        Ankit Jain <radical@gmail.com>, Rik van Riel <riel@redhat.com>,
        Nikanth Karthikesan <knikanth@suse.de>,
        LKML <linux-kernel@vger.kernel.org>, Andi Kleen <andi@firstfloor.org>
To: Wu Fengguang <fengguang.wu@intel.com>
Return-path: <owner-linux-mm@kvack.org>
In-Reply-To: <20111128023922.GA2141@localhost>
Sender: owner-linux-mm@kvack.org
List-Id: linux-fsdevel.vger.kernel.org



On 11/28/2011 03:39 AM, Wu Fengguang wrote:
> On Fri, Nov 25, 2011 at 08:36:33AM +0800, Dave Chinner wrote:
>> On Thu, Nov 24, 2011 at 11:28:22PM +0100, Jan Kara wrote:
>>> On Mon 21-11-11 19:35:40, Wu Fengguang wrote:
>>>> On Mon, Nov 21, 2011 at 06:01:37PM +0800, Christoph Hellwig wrote:
>>>>> On Mon, Nov 21, 2011 at 05:18:21PM +0800, Wu Fengguang wrote:
>>>>>> From: Nikanth Karthikesan<knikanth@suse.de>
>>>>>>
[...]

>>
>> And one that has already been in use for exactly this purpose for
>> years. Indeed, it's far more flexible because you can give different
>> types of devices different default readahead settings quite easily,
>> and it you can set different defaults for just about any tunable
>> parameter (e.g. readahead, ctq depth, max IO sizes, etc) in the same
>> way.
>
> I'm interested in this usage, too. Would you share some of your rules?
>

FYI - This is an example of a rules Suse delivers in SLES @ s390 for a=20
while now. With little modifications it could be used for all Dave=20
mentioned above.

cat /etc/udev/rules.d/60-readahead.rules
#=20
=20
=20

# Rules to set an increased default max readahead size for s390 disk=20
devices=20
=20

# This file should be installed in /etc/udev/rules.d=20
=20
=20

#=20
=20
=20

=20
=20
=20

SUBSYSTEM!=3D"block", GOTO=3D"ra_end"=20
=20
=20

=20
=20
=20

ACTION!=3D"add", GOTO=3D"ra_end"=20
=20
=20

# on device add set initial readahead to 512 (instead of in kernel 128)=20
=20
=20

KERNEL=3D=3D"sd*[!0-9]", ATTR{queue/read_ahead_kb}=3D"512"=20
=20
=20

KERNEL=3D=3D"dasd*[!0-9]", ATTR{queue/read_ahead_kb}=3D"512"=20
=20
=20


LABEL=3D"ra_end"

--=20

Gr=FCsse / regards, Christian Ehrhardt
IBM Linux Technology Center, System z Linux Performance

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