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 745B2CDB465 for ; Thu, 19 Oct 2023 16:05:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346483AbjJSQFX (ORCPT ); Thu, 19 Oct 2023 12:05:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345104AbjJSQFU (ORCPT ); Thu, 19 Oct 2023 12:05:20 -0400 Received: from smtpout.efficios.com (unknown [IPv6:2607:5300:203:b2ee::31e5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 687F312A for ; Thu, 19 Oct 2023 09:05:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1697731516; bh=HmwG14J3AlJoFMkkIkRSsNIqRZMe3libr4mFaqc0lWQ=; h=From:To:Cc:Subject:Date:From; b=sOQBiwTuhHyiox3zgOd1KHiJH4E0m1+/QHJ135qcyd3qkrjfs25NHK7KSwkEsNHtY OBYe1p6yydyvA98wddrcu0R8YLVH04MRPcIcdx19zbQ20sl77vg8vNUzUN69M/4I7Y tl1YKxIRvBiHH4pVjUAmuDcf2ZsucjVMIJjGyIPICljcpQs6nWemi9F+RTHvzD3tq2 InVT2Q9wOAqugVbn1iwThq0WKU/zdUt5TOTHjXSJ++MUrbhuXf1ThOuc1SzTZB1EKJ OS+fdfrdzZqlGvXLKYohEC92SJFi+UDAmQM8Tn6ER1mBbHhVcKNq5HDAyeJ8u2SCYE eI1sCihlLbQDw== Received: from thinkos.internal.efficios.com (192-222-143-198.qc.cable.ebox.net [192.222.143.198]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4SBCH00lhcz1YPd; Thu, 19 Oct 2023 12:05:16 -0400 (EDT) From: Mathieu Desnoyers To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Mathieu Desnoyers , Ingo Molnar , Valentin Schneider , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Vincent Guittot , Juri Lelli , Swapnil Sapkal , Aaron Lu , Chen Yu , Tim Chen , K Prateek Nayak , "Gautham R . Shenoy" , x86@kernel.org Subject: [RFC PATCH v2 0/2] sched/fair migration reduction features Date: Thu, 19 Oct 2023 12:05:21 -0400 Message-Id: <20231019160523.1582101-1-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, This series introduces two new scheduler features: UTIL_FITS_CAPACITY and SELECT_BIAS_PREV. When used together, they achieve a 41% speedup of a hackbench workload which leaves some idle CPU time on a 192-core AMD EPYC. The main metrics which are significantly improved are: - cpu-migrations are reduced by 80%, - CPU utilization is increased by 17%. Feedback is welcome. I am especially interested to learn whether this series has positive or detrimental effects on performance of other workloads. The main changes since v1 are to take into account feedback from Chen Yu and keep a 20% margin of unused utilization in the capacity fit, and use scale_rt_capacity() which is more precise. Thanks, Mathieu Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Valentin Schneider Cc: Steven Rostedt Cc: Ben Segall Cc: Mel Gorman Cc: Daniel Bristot de Oliveira Cc: Vincent Guittot Cc: Juri Lelli Cc: Swapnil Sapkal Cc: Aaron Lu Cc: Chen Yu Cc: Tim Chen Cc: K Prateek Nayak Cc: Gautham R . Shenoy Cc: x86@kernel.org Mathieu Desnoyers (2): sched/fair: Introduce UTIL_FITS_CAPACITY feature (v2) sched/fair: Introduce SELECT_BIAS_PREV to reduce migrations kernel/sched/fair.c | 68 ++++++++++++++++++++++++++++++++++++----- kernel/sched/features.h | 12 ++++++++ kernel/sched/sched.h | 5 +++ 3 files changed, 77 insertions(+), 8 deletions(-) -- 2.39.2