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[195.135.220.15]) by mx.google.com with ESMTPS id i31si823889ede.429.2019.04.25.05.03.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 Apr 2019 05:03:25 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 43961AD45; Thu, 25 Apr 2019 12:03:24 +0000 (UTC) Date: Thu, 25 Apr 2019 14:03:22 +0200 From: Michal Hocko To: Matthew Wilcox Cc: Vlastimil Babka , lsf-pc@lists.linux-foundation.org, Linux-FSDevel , linux-mm , linux-block@vger.kernel.org, Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim , Ming Lei , linux-xfs@vger.kernel.org, Christoph Hellwig , Dave Chinner , "Darrick J . Wong" Subject: Re: [LSF/MM TOPIC] guarantee natural alignment for kmalloc()? Message-ID: <20190425120322.GW12751@dhcp22.suse.cz> References: <790b68b7-3689-0ff6-08ae-936728bc6458@suse.cz> <20190411132819.GB22763@bombadil.infradead.org> <20190425113358.GI19031@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190425113358.GI19031@bombadil.infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) 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 Thu 25-04-19 04:33:59, Matthew Wilcox wrote: > On Thu, Apr 11, 2019 at 06:28:19AM -0700, Matthew Wilcox wrote: > > On Thu, Apr 11, 2019 at 02:52:08PM +0200, Vlastimil Babka wrote: > > > In the session I hope to resolve the question whether this is indeed the > > > right thing to do for all kmalloc() users, without an explicit alignment > > > requests, and if it's worth the potentially worse > > > performance/fragmentation it would impose on a hypothetical new slab > > > implementation for which it wouldn't be optimal to split power-of-two > > > sized pages into power-of-two-sized objects (or whether there are any > > > other downsides). > > > > I think this is exactly the kind of discussion that LSFMM is for! It's > > really a whole-system question; is Linux better-off having the flexibility > > for allocators to return non-power-of-two aligned memory, or allowing > > consumers of the kmalloc API to assume that "sufficiently large" memory > > is naturally aligned. > > This has been scheduled for only the MM track. I think at least the > filesystem people should be involved in this discussion since it's for > their benefit. Agreed. I have marked it as a MM/IO/FS track, we just haven't added it to the schedule that way. I still plan to go over all topics again and consolidate the current (very preliminary) schedule. Thanks for catching this up. > Do we have an lsf-discuss mailing list this year? Might be good to > coordinate arrivals / departures for taxi sharing purposes. Yes, the list should be established AFAIK and same address as last years. -- Michal Hocko SUSE Labs