From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH v4 04/43] hpsa: clean up aborts Date: Fri, 17 Apr 2015 14:59:58 +0200 Message-ID: <553103CE.40108@suse.de> References: <20150416134224.30238.66082.stgit@brunhilda> <20150416134703.30238.10876.stgit@brunhilda> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from cantor2.suse.de ([195.135.220.15]:58909 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752488AbbDQM77 (ORCPT ); Fri, 17 Apr 2015 08:59:59 -0400 In-Reply-To: <20150416134703.30238.10876.stgit@brunhilda> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Don Brace , scott.teel@pmcs.com, Kevin.Barnett@pmcs.com, james.bottomley@parallels.com, hch@infradead.org, Justin.Lindley@pmcs.combrace@pmcs.com Cc: linux-scsi@vger.kernel.org On 04/16/2015 03:47 PM, Don Brace wrote: > From: Stephen Cameron >=20 > Do not send aborts to logical devices that do not support aborts >=20 > Instead of relying on what the Smart Array claims for supporting logi= cal > drives, simply try an abort and see how it responds at device discove= ry > time. This way devices that do support aborts (e.g. MSA2000) can wor= k > and we do not waste time trying to send aborts to logical drives that= do > not support them (important for high IOPS devices.) >=20 > While rescanning devices only test whether devices support aborts > the first time we encounter a device rather than every time. >=20 > Some Smart Arrays required aborts to be sent with tags in > the wrong endian byte order. To avoid having to know about > this, we would send two aborts with tags with each endian order. > On high IOPS devices, this turns out to be not such a hot idea. > So we now have a list of the devices that got the tag backwards, > and we only send it one way. >=20 > If all available commands are outstanding and the abort handler > is invoked, the abort handler may not be able to allocate a command > and may busy-wait excessivly. Reserve a small number of commands > for the abort handler and limit the number of concurrent abort > requests to the number of reserved commands. >=20 > Reviewed-by: Scott Teel > Reviewed-by: Kevin Barnett > Signed-off-by: Don Brace Reviewed-by: Hannes Reinecke Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg GF: F. Imend=C3=B6rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG N=C3=BCrnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html