Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933351Ab3HNWc7 (ORCPT ); Wed, 14 Aug 2013 18:32:59 -0400 Received: from g5t0009.atlanta.hp.com ([15.192.0.46]:8844 "EHLO g5t0009.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933126Ab3HNWc5 convert rfc822-to-8bit (ORCPT ); Wed, 14 Aug 2013 18:32:57 -0400 From: "Miller, Mike (OS Dev)" To: James Bottomley , "mikem@thumper.usa.hp.com" CC: Andrew Morton , Jens Axboe , LKML-scsi , LKML , "thenzl@redhat.com" , "bubrown@redhat.com" , "scameron@beardog.cce.hp.com" Subject: RE: [PATCH 1/1] cciss: set max scatter gather entries to 32 on P600 Thread-Topic: [PATCH 1/1] cciss: set max scatter gather entries to 32 on P600 Thread-Index: AQHOmTUMBJgAlQMRzEuEeNzyVToHo5mVOq6A Date: Wed, 14 Aug 2013 21:41:14 +0000 Message-ID: <48275AD710FCA34184C2B6186B4016B32735BD62@G6W2491.americas.hpqcorp.net> References: <20130814205236.GB23042@beardog.cce.hp.com> <1376515627.2028.41.camel@dabdike.int.hansenpartnership.com> In-Reply-To: <1376515627.2028.41.camel@dabdike.int.hansenpartnership.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [16.201.12.29] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1875 Lines: 44 -----Original Message----- From: James Bottomley [mailto:James.Bottomley@HansenPartnership.com] Sent: Wednesday, August 14, 2013 4:27 PM To: Miller, Mike (OS Dev); mikem@thumper.usa.hp.com Cc: Andrew Morton; Jens Axboe; LKML-scsi; LKML; thenzl@redhat.com; bubrown@redhat.com; scameron@beardog.cce.hp.com Subject: Re: [PATCH 1/1] cciss: set max scatter gather entries to 32 on P600 On Wed, 2013-08-14 at 15:52 -0500, Mike Miller wrote: > Patch 1/1 > > From: Mike Miller > > At one time we used to set the maximum number of scatter gather > elements on all Smart Array controllers to 32. At some point in time > the firmware began to write the "appropriate" value for each controller into the config table. > The cciss driver would then read that and set h->maxsgentries. > > h->maxsgentries = readl(&(h->cfgtable->MaxSGElements); > > On the P600 that value is 544. Under some workloads a significant > performance reduction may result. This patch forces the P600 to use > only 32 scatter gather elements. Other controllers are not affected. > > Signed-off-by: Mike Miller > Signed-off-by: Dwight (Bud) Brown > Signed-off-by: Tomas Henzl > Acked-by: Stephen M. Cameron I don't quite understand the signoff chain on this patch. For a one line patch, are you saying it has three authors? James The patch origin is unknown. I got it from Tomas and Bud who think it may have originated from HP. I cleaned it up, compile tested it, and sent it on. I'll review my procedures for future patches. -- mikem -- 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/