From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f69.google.com (mail-wm0-f69.google.com [74.125.82.69]) by kanga.kvack.org (Postfix) with ESMTP id E28AC6B0007 for ; Tue, 3 Jul 2018 15:19:49 -0400 (EDT) Received: by mail-wm0-f69.google.com with SMTP id q8-v6so1126760wmc.2 for ; Tue, 03 Jul 2018 12:19:49 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id e140-v6sor609935wma.4.2018.07.03.12.19.48 for (Google Transport Security); Tue, 03 Jul 2018 12:19:48 -0700 (PDT) MIME-Version: 1.0 References: <153063036670.1818.16010062622751502.stgit@localhost.localdomain> <153063054586.1818.6041047871606697364.stgit@localhost.localdomain> <20180703152723.GB21590@bombadil.infradead.org> <2d845a0d-d147-7250-747e-27e493b6a627@virtuozzo.com> <20180703175808.GC4834@bombadil.infradead.org> <94c282fd-1b5a-e959-b344-01a51fd5fc2e@virtuozzo.com> In-Reply-To: <94c282fd-1b5a-e959-b344-01a51fd5fc2e@virtuozzo.com> From: Shakeel Butt Date: Tue, 3 Jul 2018 12:19:35 -0700 Message-ID: Subject: Re: [PATCH v8 03/17] mm: Assign id to every memcg-aware shrinker Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Kirill Tkhai Cc: Matthew Wilcox , Vladimir Davydov , Alexander Viro , Johannes Weiner , Michal Hocko , Thomas Gleixner , Philippe Ombredanne , stummala@codeaurora.org, gregkh@linuxfoundation.org, Stephen Rothwell , Roman Gushchin , mka@chromium.org, Tetsuo Handa , Chris Wilson , longman@redhat.com, Minchan Kim , Huang Ying , Mel Gorman , jbacik@fb.com, Guenter Roeck , LKML , Linux MM , lirongqing@baidu.com, Andrey Ryabinin , Andrew Morton On Tue, Jul 3, 2018 at 12:13 PM Kirill Tkhai wrote: > > On 03.07.2018 20:58, Matthew Wilcox wrote: > > On Tue, Jul 03, 2018 at 06:46:57PM +0300, Kirill Tkhai wrote: > >> shrinker_idr now contains only memcg-aware shrinkers, so all bits from memcg map > >> may be potentially populated. In case of memcg-aware shrinkers and !memcg-aware > >> shrinkers share the same numbers like you suggest, this will lead to increasing > >> size of memcg maps, which is bad for memory consumption. So, memcg-aware shrinkers > >> should to have its own IDR and its own numbers. The tricks like allocation big > >> IDs for !memcg-aware shrinkers seem bad for me, since they make the code more > >> complicated. > > > > Do we really have so very many !memcg-aware shrinkers? > > > > $ git grep -w register_shrinker |wc > > 32 119 2221 > > $ git grep -w register_shrinker_prepared |wc > > 4 13 268 > > (that's an overstatement; one of those is the declaration, one the definition, > > and one an internal call, so we actually only have one caller of _prepared). > > > > So it looks to me like your average system has one shrinker per > > filesystem, one per graphics card, one per raid5 device, and a few > > miscellaneous. I'd be shocked if anybody had more than 100 shrinkers > > registered on their laptop. > > > > I think we should err on the side of simiplicity and just have one IDR for > > every shrinker instead of playing games to solve a theoretical problem. > > It just a standard situation for the systems with many containers. Every mount > introduce a new shrinker to the system, so it's easy to see a system with > 100 or ever 1000 shrinkers. AFAIR, Shakeel said he also has the similar > configurations. > I can say on our production systems, a couple thousand shrinkers is normal. Shakeel