From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH V8 1/7] blk-mq-sched: fix scheduler bad performance Date: Fri, 13 Oct 2017 11:30:16 -0600 Message-ID: References: <20171013172459.1376-1-ming.lei@redhat.com> <20171013172459.1376-2-ming.lei@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20171013172459.1376-2-ming.lei@redhat.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org 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 List-Id: linux-scsi@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