From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753629Ab0KXPWN (ORCPT ); Wed, 24 Nov 2010 10:22:13 -0500 Received: from na3sys009aog103.obsmtp.com ([74.125.149.71]:49230 "EHLO na3sys009aog103.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751301Ab0KXPWK (ORCPT ); Wed, 24 Nov 2010 10:22:10 -0500 From: "Yang, Bo" To: James Bottomley CC: "'linux-scsi@vger.kernel.org'" , "'akpm@osdl.org'" , "'linux-kernel@vger.kernel.org'" , Tomas Henzl , "Daftardar, Jayant" , "Prabhakaran, Rajesh" Date: Wed, 24 Nov 2010 08:22:21 -0700 Subject: RE: [PATCH 8/9] scsi: megaraid_sas - Driver take some workloads from FW Thread-Topic: [PATCH 8/9] scsi: megaraid_sas - Driver take some workloads from FW Thread-Index: AcuIEqZLLSCnFw0qQv6jwQQTCLAWhQD1sPnw Message-ID: <4B6A08C587958942AA3002690DD4F8C30106B1DEB9@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> <1290189181.23556.77.camel@mulgrave.site> In-Reply-To: <1290189181.23556.77.camel@mulgrave.site> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id oAOFMSNu013125 James, Our megaraid sas driver only implemented the part of the XOR calculation and copy capability(moving data between 2 buffers) for the RAID5 cmds which FW asks driver to do. When fw received very heavy I/Os and there are high pending cmds in FW, fw will ask the help from driver to finish some cmds and reduce the fw heavy load. Driver will only do part of the RAID5 (not take the jobs) from FW. Driver is not duplicating Parity calculation done on dm/md. Thanks, Bo Yang -----Original Message----- From: James Bottomley [mailto:James.Bottomley@HansenPartnership.com] Sent: Friday, November 19, 2010 12:53 PM To: Yang, Bo Cc: 'linux-scsi@vger.kernel.org'; 'akpm@osdl.org'; 'linux-kernel@vger.kernel.org'; Tomas Henzl Subject: Re: [PATCH 8/9] scsi: megaraid_sas - Driver take some workloads from FW 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 {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Yang, Bo" Subject: RE: [PATCH 8/9] scsi: megaraid_sas - Driver take some workloads from FW Date: Wed, 24 Nov 2010 08:22:21 -0700 Message-ID: <4B6A08C587958942AA3002690DD4F8C30106B1DEB9@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> <1290189181.23556.77.camel@mulgrave.site> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <1290189181.23556.77.camel@mulgrave.site> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: James Bottomley Cc: "'linux-scsi@vger.kernel.org'" , "'akpm@osdl.org'" , "'linux-kernel@vger.kernel.org'" , Tomas Henzl , "Daftardar, Jayant" , "Prabhakaran, Rajesh" List-Id: linux-scsi@vger.kernel.org SmFtZXMsDQoNCk91ciBtZWdhcmFpZCBzYXMgZHJpdmVyIG9ubHkgaW1wbGVtZW50ZWQgdGhlIHBh cnQgb2YgdGhlIFhPUiBjYWxjdWxhdGlvbiBhbmQgY29weSBjYXBhYmlsaXR5KG1vdmluZyBkYXRh IGJldHdlZW4gMiBidWZmZXJzKSBmb3IgdGhlIFJBSUQ1IGNtZHMgd2hpY2ggRlcgYXNrcyBkcml2 ZXIgdG8gZG8uICBXaGVuIGZ3IHJlY2VpdmVkIHZlcnkgaGVhdnkgSS9PcyBhbmQgdGhlcmUgYXJl IGhpZ2ggcGVuZGluZyBjbWRzIGluIEZXLCBmdyB3aWxsIGFzayB0aGUgaGVscCBmcm9tIGRyaXZl ciB0byBmaW5pc2ggc29tZSBjbWRzIGFuZCByZWR1Y2UgdGhlIGZ3IGhlYXZ5IGxvYWQuICBEcml2 ZXIgd2lsbCBvbmx5IGRvIHBhcnQgb2YgdGhlIFJBSUQ1IChub3QgdGFrZSB0aGUgam9icykgZnJv bSBGVy4gIERyaXZlciBpcyBub3QgZHVwbGljYXRpbmcgUGFyaXR5IGNhbGN1bGF0aW9uIGRvbmUg b24gZG0vbWQuDQoNClRoYW5rcywNCg0KQm8gWWFuZyAgDQoNCg0KDQotLS0tLU9yaWdpbmFsIE1l c3NhZ2UtLS0tLQ0KRnJvbTogSmFtZXMgQm90dG9tbGV5IFttYWlsdG86SmFtZXMuQm90dG9tbGV5 QEhhbnNlblBhcnRuZXJzaGlwLmNvbV0gDQpTZW50OiBGcmlkYXksIE5vdmVtYmVyIDE5LCAyMDEw IDEyOjUzIFBNDQpUbzogWWFuZywgQm8NCkNjOiAnbGludXgtc2NzaUB2Z2VyLmtlcm5lbC5vcmcn OyAnYWtwbUBvc2RsLm9yZyc7ICdsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnJzsgVG9tYXMg SGVuemwNClN1YmplY3Q6IFJlOiBbUEFUQ0ggOC85XSBzY3NpOiBtZWdhcmFpZF9zYXMgLSBEcml2 ZXIgdGFrZSBzb21lIHdvcmtsb2FkcyBmcm9tIEZXDQoNCk9uIEZyaSwgMjAxMC0xMS0xOSBhdCAx MDo0MyAtMDcwMCwgWWFuZywgQm8gd3JvdGU6DQo+IERyaXZlciBhZGRlZCB0aGUgbmV3IGZlYXR1 cmUgdG8gdGFrZSBzb21lIG9mIHRoZSB3b3JrbG9hZHMgZnJvbSBGVyB0byBpbmNyZWFzZQ0KPiBw ZXJmb3JtYW5jZSBvZiB0aGUgaU1SIGNvbnRyb2xsZXIuICBGVyBhc3NpZ25zIHRoZSByZWFkIGNt ZHMgYmFjayB0byBkcml2ZXINCj4gd2hpY2ggd2lsbCBpbmNyZWFzZSB0aGUgcGVyZm9ybWFuY2Ug Zm9yIG1lZ2FyYWlkIHNhcyBpTVIgY29udHJvbGxlci4NCg0KSnVzdCBvbiBhIHByb2Nlc3Mgbm90 ZTogeW91IGRvbid0IGhhdmUgdG8gY2MgbWUgYXQgZXZlcnkga25vd24NCmFkZHJlc3MgLi4uIEkg ZG8gcmVhZCBsaW51eC1zY3NpIC4uLg0KDQpNeSBmaXJzdCB0YWtlIG9uIHRoaXMgcGF0Y2ggaXMg dGhhdCB5b3UncmUgYmFzaWNhbGx5IHBhc3NpbmcgZGF0YSBiYWNrDQp0byB0aGUga2VybmVsIGZv ciBSQUlELU4gcGFyaXR5IGNhbGN1bGF0aW9ucy4gIFRoaXMgZWZmZWN0aXZlbHkgbWFrZXMNCnlv dXIgUkFJRCBvbmUgb2YgdGhvc2UgcHNldWRvIEhXIG9uZXMuICBJbiB3aGljaCBjYXNlLCB3aHkg bm90IHNpbXBseQ0KYWJhbmRvbiB0aGUgSFcgcmFpZCBwaWVjZSBhbmQgaGF2ZSBpdCBhbGwgZG9u ZSBieSBETS9NRCwgd2hpY2ggYXJlIHdlbGwNCm9wdGltaXNlZCBmb3IgYWxsIHR5cGVzIG9mIFJB SUQ/ICBUaGUgcmVhc29uIGZvciBhc2tpbmcgaXMgdGhhdCB3ZSdyZQ0KdHJ5aW5nIHRvIHJlZHVj ZSB0aGUgbnVtYmVyIG9mIGluLWtlcm5lbCByYWlkIGltcGxlbWVudGF0aW9ucyBhbmQgdGhpcw0K aXMgZ29pbmcgaW4gdGhlIHdyb25nIGRpcmVjdGlvbi4NCg0KSmFtZXMNCg0KDQo=