From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id E4D496B04FA for ; Mon, 21 Nov 2016 09:03:44 -0500 (EST) Received: by mail-wm0-f72.google.com with SMTP id i131so40170519wmf.3 for ; Mon, 21 Nov 2016 06:03:44 -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 x69si13669768wme.157.2016.11.21.06.03.43 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 21 Nov 2016 06:03:43 -0800 (PST) Received: by mail-wm0-f68.google.com with SMTP id g23so2295312wme.1 for ; Mon, 21 Nov 2016 06:03:43 -0800 (PST) Date: Mon, 21 Nov 2016 15:03:41 +0100 From: Michal Hocko Subject: Re: [RESEND][v1 0/3] Support memory cgroup hotplug Message-ID: <20161121140340.GC18112@dhcp22.suse.cz> References: <1479253501-26261-1-git-send-email-bsingharora@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1479253501-26261-1-git-send-email-bsingharora@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Balbir Singh Cc: mpe@ellerman.id.au, hannes@cmpxchg.org, vdavydov.dev@gmail.com, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, Tejun Heo , Andrew Morton On Wed 16-11-16 10:44:58, 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. I didn't get to read patches yet (I am currently swamped by emails after longer vacation so bear with me) but this doesn't tell us _why_ we want this and how much we can actaully save. In general being dynamic is more complex and most systems tend to have possible_nodes close to online_nodes in my experience (well at least on most reasonable architectures). I would also appreciate some highlevel description of the implications. E.g. how to we synchronize with the hotplug operations when iterating node specific data structures. Thanks! -- 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