From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kashyap Desai Subject: RE: [PATCH] megaraid_sas: Enable shared host tag map Date: Mon, 24 Nov 2014 21:22:49 +0530 Message-ID: References: <1416843235-35947-1-git-send-email-hare@suse.de> <20141124153558.GA27364@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from exprod7og104.obsmtp.com ([64.18.2.161]:44141 "EHLO exprod7og104.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751758AbaKXPwy (ORCPT ); Mon, 24 Nov 2014 10:52:54 -0500 Received: by mail-la0-f50.google.com with SMTP id pv20so7918714lab.9 for ; Mon, 24 Nov 2014 07:52:51 -0800 (PST) In-Reply-To: <20141124153558.GA27364@lst.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Christoph Hellwig , Hannes Reinecke Cc: James Bottomley , Sumit Saxena , linux-scsi@vger.kernel.org > -----Original Message----- > From: Christoph Hellwig [mailto:hch@lst.de] > Sent: Monday, November 24, 2014 9:06 PM > To: Hannes Reinecke > Cc: James Bottomley; Sumit Saxena; Kashyap Desai; Christoph Hellwig; linux- > scsi@vger.kernel.org > Subject: Re: [PATCH] megaraid_sas: Enable shared host tag map > > On Mon, Nov 24, 2014 at 04:33:55PM +0100, Hannes Reinecke wrote: > > The megaraid SAS driver uses a shared host tag map internally, so we > > should be telling the block layer about it. > > But it doesn't make use of request->tag yet. This would only be useful if you > got rid of the internal tag allocator. I have patch for code changes in this particular area and that is currently under internal test cycle. Next patch series will start using shared blk tag for internal MPT frame allocation. It will get-rid-off MPT frame pool link list completely and also does lots of refactor w.r.t MFI/MPT frame corruption issue. Using shared blk tag gave good performance improvement as driver completely removed mpt frame spin lock used in megasas_get_cmd_fusion/ megasas_return_cmd_fusion. ~ Kashyap