Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754009Ab3GXUz4 (ORCPT ); Wed, 24 Jul 2013 16:55:56 -0400 Received: from longford.logfs.org ([213.229.74.203]:59893 "EHLO longford.logfs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753520Ab3GXUzx (ORCPT ); Wed, 24 Jul 2013 16:55:53 -0400 Date: Wed, 24 Jul 2013 15:23:57 -0400 From: =?utf-8?B?SsO2cm4=?= Engel To: Baruch Even Cc: Nagalakshmi Nandigama , Sreekanth Reddy , Support , "James E.J. Bottomley" , DL-MPTFusionLinux@lsi.com, linux-scsi , linux-kernel@vger.kernel.org, mit@purestorage.com Subject: Re: [PATCH] mpt2sas: don't handle broadcast primitives Message-ID: <20130724192357.GC3641@logfs.org> References: <20130719220659.GF29404@logfs.org> <20130719221143.GG29404@logfs.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2195 Lines: 46 On Wed, 24 July 2013 23:42:22 +0300, Baruch Even wrote: > On Sat, Jul 20, 2013 at 1:11 AM, Jörn Engel wrote: > > On Fri, 19 July 2013 18:06:59 -0400, Jörn Engel wrote: > >> > >> The handling of broadcast primitives involves > >> _scsih_block_io_all_device(), which does what the name implies. I have > >> observed cases with >60s of blocking io on all devices, caused by a > >> single bad device. The downsides of this code are obvious, while the > >> upsides are more elusive. > > > > And since this patch looks more like an April fools joke: I have > > gathered a few machine-months of testing, including tortures that > > specifically stress the removed codepaths. This is a serious > > submission and unless someone can show me a _very_ good reason for > > keeping the deleted code, I would like to get it merged. > > This would seem to cause an IO pause through the host whenever there > is a disk removal/insertion or SES (SAS expander) change which seems > like a bad proposition indeed. The part of the work that this code > seems to handle is that when such a change happens something needs to > detect the dead IOs (f.ex. surprise disk removal) but I believe that > the SAS HBA firmware will do that internally already so I do think > this code is needless. > > The only thing I'd like not to lose is the actual notification and > ability to log the fact that there was a broadcast notification on the > SAS network. I agree logging would be nice. However my attempts to keep logging and remove the IO pause were unsuccessful. Apparently something inside _scsih_sas_broadcast_primitive_event() is required to get future events. If someone from LSI with data sheets and understanding of the firmware can do a better patch, I would be happy. Jörn -- The story so far: In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move. -- Douglas Adams -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/