From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH] fix for BZ 8426 - massive slowdown on SCSI CD/DVD drive connected to mptspi driver Date: Tue, 22 May 2007 16:27:14 -0500 Message-ID: <1179869235.3738.55.camel@mulgrave.il.steeleye.com> References: <1178567987.27671.20.camel@deimos.americas.hpqcorp.net> <1179865510.5479.17.camel@phobos> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from hancock.steeleye.com ([71.30.118.248]:41906 "EHLO hancock.sc.steeleye.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757829AbXEVV1R (ORCPT ); Tue, 22 May 2007 17:27:17 -0400 In-Reply-To: <1179865510.5479.17.camel@phobos> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Doug Chapman Cc: eric.moore@lsi.com, linux-scsi@vger.kernel.org On Tue, 2007-05-22 at 14:25 -0600, Doug Chapman wrote: > Eric, > > Sorry to bother you on this again, I realize you are very busy. > > >From our off-list email and from your comments to Chip Coldwell in > redhat BZ 225177 it sounded like you were prepared to ACK this. Any > chance you could send your official ACK so this can be committed? > > much appreciated, Actually I'd like a little analysis of why first, please Eric. It seems to me, with the current wrong ordering in the initialisation results in a large queue depth being given to the DVD (which are habitually very low queue depth ... or even untagged beasts). So does the slowdown result from the fusion accepting N commands for the DVD and then rejecting N-1 of them resulting in ping pong between the mid-layer and driver? If so, we probably want to fix the command throttling in the driver. James