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[150.101.137.136]) by mx.google.com with ESMTP id k134si3050699pga.401.2019.01.30.17.34.05 for ; Wed, 30 Jan 2019 17:34:06 -0800 (PST) Received-SPF: neutral (google.com: 150.101.137.136 is neither permitted nor denied by best guess record for domain of david@fromorbit.com) client-ip=150.101.137.136; Authentication-Results: mx.google.com; spf=neutral (google.com: 150.101.137.136 is neither permitted nor denied by best guess record for domain of david@fromorbit.com) smtp.mailfrom=david@fromorbit.com Received: from ppp59-167-129-252.static.internode.on.net (HELO dastard) ([59.167.129.252]) by ipmail01.adl6.internode.on.net with ESMTP; 31 Jan 2019 12:04:03 +1030 Received: from dave by dastard with local (Exim 4.80) (envelope-from ) id 1gp1Ex-0001yb-4V; Thu, 31 Jan 2019 12:34:03 +1100 Date: Thu, 31 Jan 2019 12:34:03 +1100 From: Dave Chinner To: Chris Mason 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" Subject: Re: [PATCH 1/2] Revert "mm: don't reclaim inodes with many attached pages" Message-ID: <20190131013403.GI4205@dastard> References: <20190130041707.27750-1-david@fromorbit.com> <20190130041707.27750-2-david@fromorbit.com> <25EAF93D-BC63-4409-AF21-F45B2DDF5D66@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <25EAF93D-BC63-4409-AF21-F45B2DDF5D66@fb.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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=202441 > > I'm a little confused by the latest comment in the bz: > > https://bugzilla.kernel.org/show_bug.cgi?id=202441#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. > Roman beat me to suggesting Rik's followup. We hit a different 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. Cheers, Dave. -- Dave Chinner david@fromorbit.com