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 584016B0069 for ; Wed, 23 Nov 2016 02:25:47 -0500 (EST) Received: by mail-wm0-f69.google.com with SMTP id m203so3007356wma.2 for ; Tue, 22 Nov 2016 23:25:47 -0800 (PST) Received: from mail-wm0-f68.google.com (mail-wm0-f68.google.com. [74.125.82.68]) by mx.google.com with ESMTPS id t14si1134635wme.122.2016.11.22.23.25.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 22 Nov 2016 23:25:46 -0800 (PST) Received: by mail-wm0-f68.google.com with SMTP id m203so848372wma.3 for ; Tue, 22 Nov 2016 23:25:45 -0800 (PST) Date: Wed, 23 Nov 2016 08:25:44 +0100 From: Michal Hocko Subject: Re: [mm v2 0/3] Support memory cgroup hotplug Message-ID: <20161123072543.GD2864@dhcp22.suse.cz> References: <1479875814-11938-1-git-send-email-bsingharora@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1479875814-11938-1-git-send-email-bsingharora@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Balbir Singh Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, Tejun Heo , Andrew Morton , Johannes Weiner , Vladimir Davydov On Wed 23-11-16 15:36:51, Balbir Singh wrote: > In the absence of hotplug we use extra memory proportional to > (possible_nodes - online_nodes) * number_of_cgroups. PPC64 has a patch > to disable large consumption with large number of cgroups. This patch > adds hotplug support to memory cgroups and reverts the commit that > limited possible nodes to online nodes. Balbir, I have asked this in the previous version but there still seems to be a lack of information of _why_ do we want this, _how_ much do we save on the memory overhead on most systems and _why_ the additional complexity is really worth it. Please make sure to add all this in the cover letter. I still didn't get to look into those patches because I am swamped with other things but to be honest I do not really see a strong justification to make it high priority for me. > Cc: Tejun Heo > Cc: Andrew Morton > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Vladimir Davydov > > I've tested this patches under a VM with two nodes and movable > nodes enabled. I've offlined nodes and checked that the system > and cgroups with tasks deep in the hierarchy continue to work > fine. > > These patches are on top of linux-next (20161117) > > Changelog v2: > Add get/put_online_mems() around node iteration > Use MEM_OFFLINE/MEM_ONLINE instead of MEM_GOING_OFFLINE/ONLINE > > Balbir Singh (3): > mm: Add basic infrastructure for memcg hotplug support > mm: Move operations to hotplug callbacks > powerpc/mm: fix node_possible_map limitations > > arch/powerpc/mm/numa.c | 7 ---- > mm/memcontrol.c | 107 +++++++++++++++++++++++++++++++++++++++++++------ > 2 files changed, 94 insertions(+), 20 deletions(-) > > -- > 2.5.5 -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org