From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:42896 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726060AbfAaPt0 (ORCPT ); Thu, 31 Jan 2019 10:49:26 -0500 From: Chris Mason Subject: Re: [PATCH 1/2] Revert "mm: don't reclaim inodes with many attached pages" Date: Thu, 31 Jan 2019 15:48:11 +0000 Message-ID: References: <20190130041707.27750-1-david@fromorbit.com> <20190130041707.27750-2-david@fromorbit.com> <25EAF93D-BC63-4409-AF21-F45B2DDF5D66@fb.com> <20190131013403.GI4205@dastard> In-Reply-To: <20190131013403.GI4205@dastard> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Dave Chinner Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-xfs@vger.kernel.org" , Roman Gushchin , "akpm@linux-foundation.org" , "mhocko@kernel.org" , "vdavydov.dev@gmail.com" On 30 Jan 2019, at 20:34, Dave Chinner wrote: > On Wed, Jan 30, 2019 at 12:21:07PM +0000, Chris Mason wrote: >> >> >> On 29 Jan 2019, at 23:17, Dave Chinner wrote: >> >>> From: Dave Chinner >>> >>> This reverts commit a76cf1a474d7dbcd9336b5f5afb0162baa142cf0. >>> >>> This change causes serious changes to page cache and inode cache >>> behaviour and balance, resulting in major performance regressions >>> when combining worklaods such as large file copies and kernel >>> compiles. >>> >>> https://bugzilla.kernel.org/show_bug.cgi?id=3D202441 >> >> I'm a little confused by the latest comment in the bz: >> >> https://bugzilla.kernel.org/show_bug.cgi?id=3D202441#c24 > > Which says the first patch that changed the shrinker behaviour is > the underlying cause of the regression. > >> Are these reverts sufficient? > > I think so. Based on the latest comment: "If I had been less strict in my testing I probably would have=20 discovered that the problem was present earlier than 4.19.3. Mr Gushins=20 commit made it more visible. I'm going back to work after two days off, so I might not be able to=20 respond inside your working hours, but I'll keep checking in on this as=20 I get a chance." I don't think the reverts are sufficient. > >> Roman beat me to suggesting Rik's followup. We hit a different=20 >> problem >> in prod with small slabs, and have a lot of instrumentation on Rik's >> code helping. > > I think that's just another nasty, expedient hack that doesn't solve > the underlying problem. Solving the underlying problem does not > require changing core reclaim algorithms and upsetting a page > reclaim/shrinker balance that has been stable and worked well for > just about everyone for years. > Things are definitely breaking down in non-specialized workloads, and=20 have been for a long time. -chris