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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 F3B63C2BA83 for ; Thu, 13 Feb 2020 10:31:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA68C20873 for ; Thu, 13 Feb 2020 10:31:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="086QjF+U" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729685AbgBMKbb (ORCPT ); Thu, 13 Feb 2020 05:31:31 -0500 Received: from merlin.infradead.org ([205.233.59.134]:46482 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726232AbgBMKba (ORCPT ); Thu, 13 Feb 2020 05:31:30 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=wGenxf8UJH3izSqwDx/MBzsW0er3OIFpLvfK35ZpkIE=; b=086QjF+UsBncBX6aGl6GNjoS7r vlwpOT3AVbX5mAt3khO6zseZ4xHUmYr5YgCvsEOi3B/5GZUgvNPpZAERyN9Q71e8owhHAaQ58xx3/ tBITRL4NzDRfUYNnPrgk5CU/AIWu1TaDq50mUMtHaugjzbuhDAZrIx59kfKI8vmSYZD2Vl2l72g5I 9fnSaUzvWrDGOOwG+aknLsoS7bli1wFyoJ6c9hm2aKs0MnUKoCetNxdsTaS9cleDFKxL9/0uqVxqV UXkVb7LoW+aekkeA03M9L6NkUZxt2EFHNtSjMyd+qC3Ahn594Ms7vTda3fx1RwCijgEXEDwUQo0tn AvDTE3zA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1j2Bm3-0007uX-Cl; Thu, 13 Feb 2020 10:31:11 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 2EFEC300446; Thu, 13 Feb 2020 11:29:19 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id BB29720206D61; Thu, 13 Feb 2020 11:31:08 +0100 (CET) Date: Thu, 13 Feb 2020 11:31:08 +0100 From: Peter Zijlstra To: Mel Gorman Cc: Vincent Guittot , Ingo Molnar , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Valentin Schneider , Phil Auld , LKML Subject: Re: [PATCH 08/11] sched/numa: Bias swapping tasks based on their preferred node Message-ID: <20200213103108.GG14914@hirez.programming.kicks-ass.net> References: <20200212093654.4816-1-mgorman@techsingularity.net> <20200212093654.4816-9-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200212093654.4816-9-mgorman@techsingularity.net> 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 Wed, Feb 12, 2020 at 09:36:51AM +0000, Mel Gorman wrote: > When swapping tasks for NUMA balancing, it is preferred that tasks move > to or remain on their preferred node. When considering an imbalance, > encourage tasks to move to their preferred node and discourage tasks from > moving away from their preferred node. Wasn't there an issue for workloads that span multiple nodes? Say a 4 node system with 2 warehouses? Then each JVM will want 2 nodes, instead of a single node, and strong preferred node stuff makes it difficult to achieve this. I forgot how we dealt with these cases, just something I worry about when reading this.