From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752725AbdJMRaU (ORCPT ); Fri, 13 Oct 2017 13:30:20 -0400 Received: from mail-it0-f44.google.com ([209.85.214.44]:48048 "EHLO mail-it0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752081AbdJMRaS (ORCPT ); Fri, 13 Oct 2017 13:30:18 -0400 X-Google-Smtp-Source: ABhQp+S8O6bLAg3kHm3cWQGl3gMP5jeMLhijSAjb1nt6m/y8dCQv2ymcuxamOQI2o5L0tTl69xUNeA== Subject: Re: [PATCH V8 1/7] blk-mq-sched: fix scheduler bad performance To: Ming Lei , linux-block@vger.kernel.org, Christoph Hellwig Cc: Bart Van Assche , Laurence Oberman , Paolo Valente , Oleksandr Natalenko , Tom Nguyen , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Omar Sandoval , John Garry References: <20171013172459.1376-1-ming.lei@redhat.com> <20171013172459.1376-2-ming.lei@redhat.com> From: Jens Axboe Message-ID: Date: Fri, 13 Oct 2017 11:30:16 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171013172459.1376-2-ming.lei@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/13/2017 11:24 AM, Ming Lei wrote: > When hw queue is busy, we shouldn't take requests from > scheduler queue any more, otherwise it is difficult to do > IO merge. > > This patch fixes the awful IO performance on some > SCSI devices(lpfc, qla2xxx, ...) when mq-deadline/kyber > is used by not taking requests if hw queue is busy. This looks fine to me, but needs a much better patch title. "fix scheduler bad performance" tells you nothing. -- Jens Axboe