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Date: Wed, 30 Nov 2011 17:09:08 +0100
From: Jan Kara <jack@suse.cz>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>,
        Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.cz>,
        Christoph Hellwig <hch@infradead.org>,
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        Linux Memory Management List <linux-mm@kvack.org>,
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        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>
Subject: Re: [PATCH 2/8] readahead: make default readahead size a kernel
 parameter
Message-ID: <20111130160908.GE4541@quack.suse.cz>
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>
 <20111130132928.GA31589@localhost>
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On Wed 30-11-11 21:29:28, Wu Fengguang wrote:
> > cat /etc/udev/rules.d/60-readahead.rules
> > # 
> >  
> >  
> > 
> > # Rules to set an increased default max readahead size for s390 disk 
> > devices 
> >  
> > 
> > # This file should be installed in /etc/udev/rules.d 
> >  
> >  
> > 
> > # 
> >  
> > SUBSYSTEM!="block", GOTO="ra_end" 
> > 
> > ACTION!="add", GOTO="ra_end" 
> > 
> > # on device add set initial readahead to 512 (instead of in kernel 128) 
> > 
> > KERNEL=="sd*[!0-9]", ATTR{queue/read_ahead_kb}="512" 
> > 
> > KERNEL=="dasd*[!0-9]", ATTR{queue/read_ahead_kb}="512" 
> 
> So SLES (@s390 and maybe more) is already shipping with 512kb
> readahead size? Good to know this!
  SLES (and openSUSE) since about 2.6.16 times is shipping with 512kb
readahead on everything... With some types of storage it makes a
significant difference.

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