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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 3168DC433ED for ; Fri, 16 Apr 2021 06:38:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 04D82610FC for ; Fri, 16 Apr 2021 06:38:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239250AbhDPGjM (ORCPT ); Fri, 16 Apr 2021 02:39:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:38818 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239192AbhDPGjH (ORCPT ); Fri, 16 Apr 2021 02:39:07 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1618555121; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=tNhVt/xCfNdMMCLz228vt0HGCkm8dnEvK2GBIRn4xww=; b=A3XQDSlnvdAvpRgcg1dXE3OCdh91lH7XApSAer4PUiCVhhZKjTFGKsC6QBSDpuen/JTu3B JRmk0OKTe0m8kUXM6S1U2eyflLQTW3PLJCQbY+/2pabax/vRN3x70ZVWZnHQogTFu/S+EQ EPkv2uvqoPeVE8NSd6Y+4AJBMjiwg/A= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id EE4E0AE86; Fri, 16 Apr 2021 06:38:40 +0000 (UTC) Date: Fri, 16 Apr 2021 08:38:40 +0200 From: Michal Hocko To: Tim Chen Cc: Shakeel Butt , Yang Shi , Johannes Weiner , Andrew Morton , Dave Hansen , Ying Huang , Dan Williams , David Rientjes , Linux MM , Cgroups , LKML Subject: Re: [RFC PATCH v1 00/11] Manage the top tier memory in a tiered memory Message-ID: References: <4a864946-a316-3d9c-8780-64c6281276d1@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4a864946-a316-3d9c-8780-64c6281276d1@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 15-04-21 15:31:46, Tim Chen wrote: > > > On 4/9/21 12:24 AM, Michal Hocko wrote: > > On Thu 08-04-21 13:29:08, Shakeel Butt wrote: > >> On Thu, Apr 8, 2021 at 11:01 AM Yang Shi wrote: > > [...] > >>> The low priority jobs should be able to be restricted by cpuset, for > >>> example, just keep them on second tier memory nodes. Then all the > >>> above problems are gone. > > > > Yes, if the aim is to isolate some users from certain numa node then > > cpuset is a good fit but as Shakeel says this is very likely not what > > this work is aiming for. > > > >> Yes that's an extreme way to overcome the issue but we can do less > >> extreme by just (hard) limiting the top tier usage of low priority > >> jobs. > > > > Per numa node high/hard limit would help with a more fine grained control. > > The configuration would be tricky though. All low priority memcgs would > > have to be carefully configured to leave enough for your important > > processes. That includes also memory which is not accounted to any > > memcg. > > The behavior of those limits would be quite tricky for OOM situations > > as well due to a lack of NUMA aware oom killer. > > > > Another downside of putting limits on individual NUMA > node is it would limit flexibility. Let me just clarify one thing. I haven't been proposing per NUMA limits. As I've said above it would be quite tricky to use and the behavior would be tricky as well. All I am saying is that we do not want to have an interface that is tightly bound to any specific HW setup (fast RAM as a top tier and PMEM as a fallback) that you have proposed here. We want to have a generic NUMA based abstraction. How that abstraction is going to look like is an open question and it really depends on usecase that we expect to see. -- Michal Hocko SUSE Labs