From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Lei Subject: Re: [LSF/MM TOPIC] Two blk-mq related topics Date: Tue, 30 Jan 2018 09:24:09 +0800 Message-ID: <20180130012408.GD17176@ming.t460p> References: <20180129154455.GB17176@ming.t460p> <1517259390.3969.41.camel@HansenPartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx1.redhat.com ([209.132.183.28]:34260 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751546AbeA3BYW (ORCPT ); Mon, 29 Jan 2018 20:24:22 -0500 Content-Disposition: inline In-Reply-To: <1517259390.3969.41.camel@HansenPartnership.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley , John Garry Cc: lsf-pc@lists.linux-foundation.org, Linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org On Mon, Jan 29, 2018 at 12:56:30PM -0800, 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. I guess Christoph still need to evaluate if there are existed issues or blockers before trying it again. And more input may be got from F2F discussion, IMHO. > > > SCSI_MQ is enabled on V3.17 firstly, but disabled at default. In > > V4.13-rc1, it is enabled at default, but later the patch is reverted > > in V4.13-rc7, and becomes disabled at default too. > > > > Now both the original reported PM issue(actually SCSI quiesce) and > > the sequential IO performance issue have been addressed. > > Is the blocker bug just not closed because no-one thought to do it: > > https://bugzilla.kernel.org/show_bug.cgi?id=178381 > > (we have confirmed that this issue is now fixed with the original > reporter?) >>From a developer view, this issue is fixed by the following commit: 3a0a52997(block, scsi: Make SCSI quiesce and resume work reliably), and it is verified by kernel list reporter. > > And did the Huawei guy (Jonathan Cameron) confirm his performance issue > was fixed (I don't think I saw email that he did)? Last time I talked with John Garry about the issue, and the merged .get_budget based patch improves much on the IO performance, but there is still a bit gap compared with legacy path. Seems a driver specific issue, remembered that removing a driver's lock can improve performance much. Garry, could you provide further update on this issue? Thanks, Ming