From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Garry Subject: Re: [PATCH 0/2] block/SCSI MQ: two RESTART related patches Date: Tue, 17 Oct 2017 16:47:23 +0100 Message-ID: <8e604f28-dd20-7818-a25b-985ab537bf70@huawei.com> References: <20171017050418.22555-1-ming.lei@redhat.com> <20171017051209.GF15996@ming.t460p> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20171017051209.GF15996@ming.t460p> Sender: linux-block-owner@vger.kernel.org To: Ming Lei , Jens Axboe , linux-block@vger.kernel.org, Christoph Hellwig Cc: Bart Van Assche , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Omar Sandoval , Linuxarm List-Id: linux-scsi@vger.kernel.org On 17/10/2017 06:12, Ming Lei wrote: > On Tue, Oct 17, 2017 at 01:04:16PM +0800, Ming Lei wrote: >> Hi Jens, >> >> The 1st patch runs idle hctx after dealy in scsi_mq_get_budget(), >> so that we can keep same behaviour with before, and it can be >> thought as a fix. >> >> The 2nd patch cleans up RESTART, and removes handling for TAG_SHARED >> from current blk-mq's RESTART mechanism because SCSI_MQ can covers its >> restart by itself, so that no need to handle TAG_SHARED in blk-mq >> RESTART. And >20% IOPS boost is observed in my rand read test over >> scsi_debug. >> >> John, please test this two patches and see if it may improve your SAS >> IO performance, and you can find the two patches in the following branch: >> >> https://github.com/ming1/linux/commits/blk_mq_improve_restart_V1 > Hi Ming, As requested, here's my figures for blk_mq_improve_restart_V1: without default SCSI_MQ, deadline scheduler, CONFIG PREEMPT off read, rw, write IOPS 989K, 113K/113K, 835K with default SCSI_MQ, mq-deadline scheduler, CONFIG PREEMPT off read, rw, write IOPS 738K, 130K/130K, 686K For axboe for-next tip (21ed538): without default SCSI_MQ, deadline scheduler, CONFIG PREEMPT off read, rw, write IOPS 977K, 117K/117K, 821K with default SCSI_MQ, mq-deadline scheduler, CONFIG PREEMPT off read, rw, write IOPS 733K, 128K/128K, 676K All cases do not have LLDD mq exposed/enabled. So unfortunately not much difference with your branch. cheers, John > Forget to mention, you need to either pull the above branch directly > or apply the two patches against for-next branch of Jens' block > tree: > > git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git #for-next >