Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756127Ab0KSRxI (ORCPT ); Fri, 19 Nov 2010 12:53:08 -0500 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:37377 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756044Ab0KSRxH (ORCPT ); Fri, 19 Nov 2010 12:53:07 -0500 Subject: Re: [PATCH 8/9] scsi: megaraid_sas - Driver take some workloads from FW From: James Bottomley To: "Yang, Bo" Cc: "'linux-scsi@vger.kernel.org'" , "'akpm@osdl.org'" , "'linux-kernel@vger.kernel.org'" , Tomas Henzl In-Reply-To: <4B6A08C587958942AA3002690DD4F8C30106A96223@cosmail02.lsi.com> References: <4B6A08C587958942AA3002690DD4F8C3D0804533@cosmail02.lsi.com> <4B6A08C587958942AA3002690DD4F8C3DBD67F68@cosmail02.lsi.com> <4B6A08C587958942AA3002690DD4F8C30106A961BD@cosmail02.lsi.com> <4B6A08C587958942AA3002690DD4F8C30106A961D6@cosmail02.lsi.com> <4B6A08C587958942AA3002690DD4F8C30106A961E4@cosmail02.lsi.com> <4B6A08C587958942AA3002690DD4F8C30106A961F2@cosmail02.lsi.com> <4B6A08C587958942AA3002690DD4F8C30106A96213@cosmail02.lsi.com> <4B6A08C587958942AA3002690DD4F8C30106A96218@cosmail02.lsi.com> <4B6A08C587958942AA3002690DD4F8C30106A9621E@cosmail02.lsi.com> <4B6A08C587958942AA3002690DD4F8C30106A96223@cosmail02.lsi.com> Content-Type: text/plain; charset="UTF-8" Date: Fri, 19 Nov 2010 11:53:01 -0600 Message-ID: <1290189181.23556.77.camel@mulgrave.site> Mime-Version: 1.0 X-Mailer: Evolution 2.30.1.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1094 Lines: 24 On Fri, 2010-11-19 at 10:43 -0700, Yang, Bo wrote: > Driver added the new feature to take some of the workloads from FW to increase > performance of the iMR controller. FW assigns the read cmds back to driver > which will increase the performance for megaraid sas iMR controller. Just on a process note: you don't have to cc me at every known address ... I do read linux-scsi ... My first take on this patch is that you're basically passing data back to the kernel for RAID-N parity calculations. This effectively makes your RAID one of those pseudo HW ones. In which case, why not simply abandon the HW raid piece and have it all done by DM/MD, which are well optimised for all types of RAID? The reason for asking is that we're trying to reduce the number of in-kernel raid implementations and this is going in the wrong direction. James -- 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/