From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [LSF/MM TOPIC] Two blk-mq related topics Date: Mon, 29 Jan 2018 15:46:23 -0800 Message-ID: <1517269583.3969.53.camel@HansenPartnership.com> References: <20180129154455.GB17176@ming.t460p> <1517259390.3969.41.camel@HansenPartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Sender: linux-block-owner@vger.kernel.org To: Jens Axboe , Ming Lei , lsf-pc@lists.linux-foundation.org, Linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org List-Id: linux-scsi@vger.kernel.org On Mon, 2018-01-29 at 14:00 -0700, Jens Axboe wrote: > On 1/29/18 1:56 PM, James Bottomley wrote: > > > > On Mon, 2018-01-29 at 23:46 +0800, Ming Lei wrote: > > [...] > > > > > > 2. When to enable SCSI_MQ at default again? > > > > I'm not sure there's much to discuss ... I think the basic answer > > is as soon as Christoph wants to try it again. > > FWIW, internally I've been running various IO intensive workloads on > what is essentially 4.12 upstream with scsi-mq the default (with > mq-deadline as the scheduler) and comparing IO workloads with a > previous 4.6 kernel (without scsi-mq), and things are looking > great. > > We're never going to iron out the last kinks with it being off > by default, I think we should attempt to flip the switch again > for 4.16. Absolutely, I agree we turn it on ASAP.  I just don't want to be on the receiving end of Linus' flamethrower because a bug we already had reported against scsi-mq caused problems.  Get confirmation from the original reporters (or as close to it as you can) that their problems are fixed and we're good to go; he won't kick us nearly as hard for new bugs that turn up. James