From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: Re: [PATCH 2/8] readahead: make default readahead size a kernel parameter Date: Wed, 30 Nov 2011 21:29:28 +0800 Message-ID: <20111130132928.GA31589@localhost> 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> <4ED629CB.401@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Cc: Dave Chinner , Jan Kara , Christoph Hellwig , Andrew Morton , Linux Memory Management List , "linux-fsdevel@vger.kernel.org" , Ankit Jain , Rik van Riel , Nikanth Karthikesan , LKML , Andi Kleen To: Christian Ehrhardt Return-path: Content-Disposition: inline In-Reply-To: <4ED629CB.401@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Wed, Nov 30, 2011 at 09:04:11PM +0800, Christian Ehrhardt wrote: >=20 >=20 > 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 > >>>>>> > [...] >=20 > >> > >> 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= ? > > >=20 > 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. It's a really good example, thank you! > cat /etc/udev/rules.d/60-readahead.rules > #=20 > =20 > =20 >=20 > # Rules to set an increased default max readahead size for s390 disk=20 > devices=20 > =20 >=20 > # This file should be installed in /etc/udev/rules.d=20 > =20 > =20 >=20 > #=20 > =20 > SUBSYSTEM!=3D"block", GOTO=3D"ra_end"=20 >=20 > ACTION!=3D"add", GOTO=3D"ra_end"=20 >=20 > # on device add set initial readahead to 512 (instead of in kernel 128)= =20 >=20 > KERNEL=3D=3D"sd*[!0-9]", ATTR{queue/read_ahead_kb}=3D"512"=20 >=20 > KERNEL=3D=3D"dasd*[!0-9]", ATTR{queue/read_ahead_kb}=3D"512"=20 So SLES (@s390 and maybe more) is already shipping with 512kb readahead size? Good to know this! Thanks, Fengguang > =20 >=20 >=20 > LABEL=3D"ra_end" >=20 > --=20 >=20 > Gr=C3=BCsse / regards, Christian Ehrhardt > IBM Linux Technology Center, System z Linux Performance -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter= .ca/ Don't email: email@kvack.org