From mboxrd@z Thu Jan 1 00:00:00 1970 From: Asai Thambi S P Subject: Re: New driver mtipx2xx submission Date: Wed, 6 Jul 2011 15:39:21 -0600 Message-ID: <4E14D609.1010404@micron.com> References: <22A973199D2C2F46933448F6E7990A300204F2BC@ntxboimbx31.micron.com> <20110428230605.78c55c70@lxorguk.ukuu.org.uk> <22A973199D2C2F46933448F6E7990A300204F728@ntxboimbx31.micron.com> <20110502184206.25907c5e@lxorguk.ukuu.org.uk> <22A973199D2C2F46933448F6E7990A300214B0D6@ntxboimbx31.micron.com> <20110511202013.075b07cc@lxorguk.ukuu.org.uk> <4DD722DB.8030303@micron.com> <22A973199D2C2F46933448F6E7990A300239EA77@ntxboimbx31.micron.com> <20110601212129.11534c55@lxorguk.ukuu.org.uk> <4DF80ADE.8020206@micron.com> <22A973199D2C2F46933448F6E7990A3002697E77@ntxboimbx31.micron.com> Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from masquerade.micron.com ([137.201.242.130]:9083 "EHLO masquerade.micron.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751012Ab1GFVjd (ORCPT ); Wed, 6 Jul 2011 17:39:33 -0400 In-Reply-To: Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Moyer Cc: Alan Cox , linux-ide@vger.kernel.org On 6/28/2011 9:18 AM, Jeff Moyer wrote: > From the perf report, I would have guessed that the CPU utilization for > the ahci test case would have been lower than the Micron block driver. > Odd, I wonder what I'm missing. Asai, did you notice if any of the CPUs > was completely pegged during testing with ahci? Yes, whichever cpu was handling interrupts was pegged in both cases. The driver is configured to use a single MSI interrupt. You're using a NUMA > box, right? I also wonder what the irq distribution looked like, and > whether rq_affinity is hurting performance for the ahci case. No, it's not a NUMA box. Our runs were done with rq_affinity=0. If you think it would be helpful, we can re-run with rq_affinity=1. Also, > does the Micron driver do any sort of interrupt coalescing that maybe > the ahci driver isn't doing? > We have a scheme to coalesce multiple completions into a single interrupt. Both drivers were using this feature for these runs.