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=-2.5 required=3.0 tests=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 9BFC6C43334 for ; Wed, 5 Sep 2018 06:42:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3666E20857 for ; Wed, 5 Sep 2018 06:42:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3666E20857 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727674AbeIELLg (ORCPT ); Wed, 5 Sep 2018 07:11:36 -0400 Received: from mx2.suse.de ([195.135.220.15]:36396 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726234AbeIELLg (ORCPT ); Wed, 5 Sep 2018 07:11:36 -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 9093DAE4F; Wed, 5 Sep 2018 06:42:54 +0000 (UTC) Date: Wed, 5 Sep 2018 08:42:52 +0200 From: Michal Hocko To: Shuah Khan Cc: Will Deacon , catalin.marinas@arm.com, sudeep.holla@arm.com, ganapatrao.kulkarni@cavium.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64: add NUMA emulation support Message-ID: <20180905064252.GW14951@dhcp22.suse.cz> References: <20180824230559.32336-1-shuah@kernel.org> <20180828174011.GE20375@arm.com> <20180829110802.GD10349@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 04-09-18 15:59:34, Shuah Khan wrote: [...] > This will support the following workload requirements: > > - reserving one or more NUMA memory nodes for class of critical tasks that require > guaranteed memory availability. > - isolate memory blocks with a guaranteed exclusive access. How do you enforce kernel doesn't allocate from those reserved nodes? They will be in a fallback zonelists so once the memory gets used on all other ones then the kernel happily spills over to your reserved node. > NUMA emulation to split the flat machine into "x" number of nodes, combined with > cpuset cgroup with the following example configuration will make it possible to > support the above workloads on non-NUMA platforms. > > numa=fake=4 > > cpuset.mems=2 > cpuset.cpus=2 > cpuset.mem_exclusive=1 (enabling exclusive use of the memory nodes by a CPU set) > cpuset.mem_hardwall=1 (separate the memory nodes that are allocated to different cgroups) This will only enforce userspace to follow and I strongly suspect that tasks in the root cgroup will be allowed to allocate as well. -- Michal Hocko SUSE Labs