From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755242AbeDPMIV (ORCPT ); Mon, 16 Apr 2018 08:08:21 -0400 Received: from mx2.suse.de ([195.135.220.15]:39387 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755230AbeDPMIT (ORCPT ); Mon, 16 Apr 2018 08:08:19 -0400 Subject: Re: [PATCH 3/3] dcache: account external names as indirectly reclaimable memory To: Michal Hocko , Johannes Weiner Cc: Minchan Kim , Roman Gushchin , linux-mm@kvack.org, Andrew Morton , Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com References: <20180305133743.12746-1-guro@fb.com> <20180305133743.12746-5-guro@fb.com> <20180413133519.GA213834@rodete-laptop-imager.corp.google.com> <20180413135923.GT17484@dhcp22.suse.cz> <13f1f5b5-f3f8-956c-145a-4641fb996048@suse.cz> <20180413142821.GW17484@dhcp22.suse.cz> <20180413143716.GA5378@cmpxchg.org> <20180416114144.GK17484@dhcp22.suse.cz> From: Vlastimil Babka Message-ID: <1475594b-c1ad-9625-7aeb-ad8ad385b793@suse.cz> Date: Mon, 16 Apr 2018 14:06:21 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180416114144.GK17484@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/16/2018 01:41 PM, Michal Hocko wrote: > On Fri 13-04-18 10:37:16, Johannes Weiner wrote: >> On Fri, Apr 13, 2018 at 04:28:21PM +0200, Michal Hocko wrote: >>> On Fri 13-04-18 16:20:00, Vlastimil Babka wrote: >>>> We would need kmalloc-reclaimable-X variants. It could be worth it, >>>> especially if we find more similar usages. I suspect they would be more >>>> useful than the existing dma-kmalloc-X :) >>> >>> I am still not sure why __GFP_RECLAIMABLE cannot be made work as >>> expected and account slab pages as SLAB_RECLAIMABLE >> >> Can you outline how this would work without separate caches? > > I thought that the cache would only maintain two sets of slab pages > depending on the allocation reuquests. I am pretty sure there will be > other details to iron out and For example the percpu (and other) array caches... > maybe it will turn out that such a large > portion of the chache would need to duplicate the state that a > completely new cache would be more reasonable. I'm afraid that's the case, yes. > Is this worth exploring > at least? I mean something like this should help with the fragmentation > already AFAIU. Accounting would be just free on top. Yep. It could be also CONFIG_urable so smaller systems don't need to deal with the memory overhead of this. So do we put it on LSF/MM agenda?