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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3BC61C433F5 for ; Wed, 18 May 2022 15:40:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239503AbiERPkB (ORCPT ); Wed, 18 May 2022 11:40:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49616 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239494AbiERPjw (ORCPT ); Wed, 18 May 2022 11:39:52 -0400 Received: from outbound-smtp03.blacknight.com (outbound-smtp03.blacknight.com [81.17.249.16]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 168B9163F66 for ; Wed, 18 May 2022 08:39:50 -0700 (PDT) Received: from mail.blacknight.com (pemlinmail06.blacknight.ie [81.17.255.152]) by outbound-smtp03.blacknight.com (Postfix) with ESMTPS id 5FA68C0AF9 for ; Wed, 18 May 2022 16:39:49 +0100 (IST) Received: (qmail 812 invoked from network); 18 May 2022 15:39:49 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.198.246]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 18 May 2022 15:39:49 -0000 Date: Wed, 18 May 2022 16:39:47 +0100 From: Mel Gorman To: Peter Zijlstra Cc: Ingo Molnar , Vincent Guittot , Valentin Schneider , Aubrey Li , LKML Subject: Re: [PATCH 3/4] sched/numa: Apply imbalance limitations consistently Message-ID: <20220518153947.GS3441@techsingularity.net> References: <20220511143038.4620-1-mgorman@techsingularity.net> <20220511143038.4620-4-mgorman@techsingularity.net> <20220518093156.GD10117@worktop.programming.kicks-ass.net> <20220518104652.GO3441@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 18, 2022 at 03:59:34PM +0200, Peter Zijlstra wrote: > On Wed, May 18, 2022 at 11:46:52AM +0100, Mel Gorman wrote: > > > > (Although I do wonder about that 25% figure in the comment; that doesn't > > > seem to relate to any actual code anymore) > > > > > > > You're right, by the end of the series it's completely inaccurate and > > currently it's not accurate if there are multiple LLCs per node. I > > adjusted the wording to "Allow a NUMA imbalance if busy CPUs is less > > than the maximum threshold. Above this threshold, individual tasks may > > be contending for both memory bandwidth and any shared HT resources." > > > > Looks good. Meanwhile I saw a 0-day complaint that this regresses > something something unixbench by a bit. Do we care enough? I suppose > this is one of those trade-off patches again, win some, loose some. I think it's a trade-off. I made a more complete response to the 0-day people at https://lore.kernel.org/all/20220518152258.GR3441@techsingularity.net/ -- Mel Gorman SUSE Labs