From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH 13/17] scsi: push host_lock down into scsi_{host,target}_queue_ready Date: Thu, 06 Feb 2014 10:41:16 -0800 Message-ID: <1391712076.22335.13.camel@dabdike> References: <20140205123930.150608699@bombadil.infradead.org> <20140205124021.286457268@bombadil.infradead.org> <1391705819.22335.8.camel@dabdike> <52F3C21F.70409@acm.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: 7bit Return-path: Received: from bedivere.hansenpartnership.com ([66.63.167.143]:49001 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753254AbaBFSlS (ORCPT ); Thu, 6 Feb 2014 13:41:18 -0500 In-Reply-To: <52F3C21F.70409@acm.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Bart Van Assche Cc: Christoph Hellwig , Jens Axboe , linux-scsi@vger.kernel.org On Thu, 2014-02-06 at 18:10 +0100, Bart Van Assche wrote: > On 02/06/14 17:56, James Bottomley wrote: > > Could you benchmark this lot and show what the actual improvement is > > just for this series, if any? > > I see a performance improvement of 12% with the SRP protocol for the > SCSI core optimizations alone (I am still busy measuring the impact of > the blk-mq conversion but I can already see that it is really > significant). Please note that the performance impact depends a lot on > the workload (number of LUNs per SCSI host e.g.) so maybe the workload I > chose is not doing justice to Christoph's work. And it's also important > to mention that with the workload I ran I was saturating the target > system CPU (a quad core Intel i5). In other words, results might be > better with a more powerful target system. On what? Just the patches I indicated or the whole series? My specific concern is that swapping a critical section for atomics may not buy us anything even on x86 and may slow down non-x86. That's the bit I'd like benchmarks to explore. James