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=-1.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS 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 0001DC004D3 for ; Mon, 22 Oct 2018 19:23:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DCA0120652 for ; Mon, 22 Oct 2018 19:23:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="BnyYXnaD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DCA0120652 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com 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 S1728963AbeJWDnM (ORCPT ); Mon, 22 Oct 2018 23:43:12 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:38568 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728161AbeJWDnM (ORCPT ); Mon, 22 Oct 2018 23:43:12 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w9MJIaWt138075; Mon, 22 Oct 2018 19:21:40 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : from : to : cc : references : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=xadglORLiZqzm+SyQ1ZZS++6VS1vZZiJyP98IzvLdpU=; b=BnyYXnaDNhwq+THxdWhM3kCa7kkKisQYJxa0jtYYscA9L3ZnkL4l4Wa9TcGGeIYQqFOv qZxfM/KF9es+tqBEqY4o5YG17kxlTFQusc+dT1ae1zcbfWHClkIY5QXFov52mZ3neE37 kQP39ux1FbincOZy+i9C+Y13f8ZitijXCLzuIJ5iTXPlzWj5ZKDRPGYXfwc7cCtd97U9 FwHs9d1kBz8JIPl/p2B5a0A5/BIuQlZLZlHcOkY/LaMhqN3CnWbUI8tchs3jPt9yoC3u 45lhbfAjTbX6iH3hFEGER1eNh9cvVePOfRh1U2eF/BFzjPFkZl2QD0x3Uwi8FGHDZ3x4 tQ== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by userp2120.oracle.com with ESMTP id 2n7w0qgksm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 22 Oct 2018 19:21:40 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w9MJLcfG022290 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 22 Oct 2018 19:21:39 GMT Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w9MJLbxZ006142; Mon, 22 Oct 2018 19:21:37 GMT Received: from [10.39.206.107] (/10.39.206.107) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 22 Oct 2018 12:21:37 -0700 Subject: Re: [PATCH 09/10] sched/fair: disable stealing if too many NUMA nodes From: Steven Sistare To: Peter Zijlstra Cc: mingo@redhat.com, subhra.mazumdar@oracle.com, dhaval.giani@oracle.com, rohit.k.jain@oracle.com, daniel.m.jordan@oracle.com, pavel.tatashin@microsoft.com, matt@codeblueprint.co.uk, umgwanakikbuti@gmail.com, riel@redhat.com, jbacik@fb.com, juri.lelli@redhat.com, linux-kernel@vger.kernel.org References: <1540220381-424433-1-git-send-email-steven.sistare@oracle.com> <1540220381-424433-10-git-send-email-steven.sistare@oracle.com> <20181022170604.GG3117@worktop.programming.kicks-ass.net> <1356a3cc-a9f2-6593-4737-1b20fc5daa75@oracle.com> Organization: Oracle Corporation Message-ID: <274b79fd-b001-3d30-3773-7f01940ca8a6@oracle.com> Date: Mon, 22 Oct 2018 15:21:20 -0400 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1356a3cc-a9f2-6593-4737-1b20fc5daa75@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9054 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1810220164 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/22/2018 2:47 PM, Steven Sistare wrote: > On 10/22/2018 1:06 PM, Peter Zijlstra wrote: >> On Mon, Oct 22, 2018 at 07:59:40AM -0700, Steve Sistare wrote: >>> The STEAL feature causes regressions on hackbench on larger NUMA systems, >>> so disable it on systems with more than sched_steal_node_limit nodes >>> (default 2). >> >> How come? From a quick read the stealing is per LLC, where do we steal >> across nodes? > > See the complete explanation in this patch. It is deeper than can be gleaned > from a quick read. I should have said a bit more. Your quick take on stealing is correct, we do not steal across nodes. However, stealing reduces average run queue length which influences wake_affine migrations. Now see the complete explanation. - Steve