From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH 1/6] libata: Do not retry commands with valid autosense Date: Mon, 03 Aug 2015 09:31:57 +0200 Message-ID: <55BF18ED.3000002@suse.de> References: <1438347728-106434-1-git-send-email-hare@suse.de> <1438347728-106434-2-git-send-email-hare@suse.de> <20150802154415.GA31100@mtj.duckdns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20150802154415.GA31100@mtj.duckdns.org> Sender: linux-ide-owner@vger.kernel.org To: Tejun Heo Cc: linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, James Bottomley List-Id: linux-scsi@vger.kernel.org On 08/02/2015 05:44 PM, Tejun Heo wrote: > Hello, >=20 > On Fri, Jul 31, 2015 at 03:02:03PM +0200, Hannes Reinecke wrote: >> If a failed command has a valid autosense there is no need to >> retry it on the ATA level; at best we're incurring the same >> error again. So rather not retry it here, but leave it to >> the SCSI layer to decide if a retry is in order. >=20 > Hmmm... I don't know. So, we change how we handle errors completely > depending on how the device reports it? Doesn't seem like a > particularly good idea to me. >=20 The whole point of the autosense feature is that you do _not_ have to fall back to the original trial-and-error libata EH, but know exactly what the problem is. Plus any retry will be giving us (in most cases) exactly the same sense code. _And_ the SCSI layer is actually able to understand the sense code, allowing him to make a better judgment on what to do with that error. So any retry in the libata layer will only slow things down, leading to the same results eventually. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: F. Imend=F6rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG N=FCrnberg)