From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Christie Subject: Re: [PATCH] Re: SYNCHRONIZE_CACHE from sd_preppare_flush does not have retries.! Date: Tue, 20 Apr 2010 14:32:44 -0500 Message-ID: <4BCE015C.7060307@cs.wisc.edu> References: <1C9608B8A4CD534FB19C7C7543CBB249021C7718FA@inbmail02.lsi.com> <201004192117.15625.bs_lists@aakef.fastmail.fm> <1C9608B8A4CD534FB19C7C7543CBB249021C7719CF@inbmail02.lsi.com> <201004201654.04934.bs_lists@aakef.fastmail.fm> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from sabe.cs.wisc.edu ([128.105.6.20]:50566 "EHLO sabe.cs.wisc.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754213Ab0DTTce (ORCPT ); Tue, 20 Apr 2010 15:32:34 -0400 In-Reply-To: <201004201654.04934.bs_lists@aakef.fastmail.fm> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Bernd Schubert Cc: "Desai, Kashyap" , James Bottomley , "linux-scsi@vger.kernel.org" On 04/20/2010 09:54 AM, Bernd Schubert wrote: > On Tuesday 20 April 2010, Desai, Kashyap wrote: >>>>>> all block device flushes or is this more device specific? I was >>>>>> thinking that we may want to create a sysfs interface under the >>> >>> block >>> >>>>>> dirs and have blk-sysfs.c and blk-barrier.c handle this. >>> >>> queue_flush >>> >>>>>> could set the timeout and retries that is set by some new files >>> >>> under >>> >>>>>> /sys/block/sdX/queue/ ? >> >> Thanks a lot for your comments. >> >> This is very close to my understanding. I feel this is more close to block >> layer and I am almost agreeing with your thought. I tried to understand >> why upstream does not have retries at queue_flush()/sd_prepare_flush() ??? >> It looks like there is not specific reason. If I am wrong can someone >> explain is there any specific reason not to set rq->retries in >> sd_prepare_flush? > > I don't understand why we should need another queue timeout, when we > already have a device timeout that is used as queue timeout? I think a possible problem is that the one timeout setting is now being used for two different operations. Currently, for disks that timeout is used for READ/WRITEs. For the sync cache, if we are hitting a problem with it taking longer than the current value of 30 secs, then could we want to set the READ/WRITE timeout to a lower value like 60 secs, but then the sync cache timeout might have to be multiple minutes.