From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE0D6C282E3 for ; Thu, 25 Apr 2019 12:03:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ADE9F218D3 for ; Thu, 25 Apr 2019 12:03:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556193807; bh=3teiry0GP5N2V5/ntUrKPPVdSbI5eu3R9VMzfBJx9CY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=aHeZH3oOdOUziq29yAp12G4a0LtFknm0idKOCeNCYVjWD4qSMwrLbCHHFXTCyFmVa Uzul4TqRfatEAYaDrl7Xn9+ie4hf9z46vb+QjjPT7t01eQ4Fir4bWxkaaeMch80lj+ 6b6YbQk8D0O0Es+9+SBrWYz91vNgHCpsiv3r+2Nw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728690AbfDYMD0 (ORCPT ); Thu, 25 Apr 2019 08:03:26 -0400 Received: from mx2.suse.de ([195.135.220.15]:55564 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728167AbfDYMDZ (ORCPT ); Thu, 25 Apr 2019 08:03:25 -0400 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) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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