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=-3.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT 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 3018AC4CEC4 for ; Thu, 19 Sep 2019 07:34:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 023E721924 for ; Thu, 19 Sep 2019 07:34:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="G9vCHWpQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388612AbfISHd7 (ORCPT ); Thu, 19 Sep 2019 03:33:59 -0400 Received: from mail-wr1-f65.google.com ([209.85.221.65]:35747 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387987AbfISHd6 (ORCPT ); Thu, 19 Sep 2019 03:33:58 -0400 Received: by mail-wr1-f65.google.com with SMTP id v8so1949555wrt.2 for ; Thu, 19 Sep 2019 00:33:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id; bh=uY1/ylDyFsviT6XapDzVuCTqMf2QKuzO/x6kAiRsGL4=; b=G9vCHWpQSry7IngYsbrlBYYhMrLzdYwOrIVMOGibLUEmXkFBiAzx4Zm0gdoHsqV8eN N3Iu9nsVRzs30bkWveu0KjmBtw8qx4i4c9wLW9fuX4LClrIh1B4Ot1vUFYXDCkNY9uK5 eqEdijMXFzRFchB0lurZ1Pa1SjUUWy3pH9VPWFn/RBULbG9qnzfB3aZtdPe85ZRJZNRV ZmHP6fXKDbxu8D4Js3+WQ6zbE2J6hY+9CdSm3rGehVcyJXv+u3rzvbylFnG7Ctb5NNR8 su1qpI3jA/o21wxps4Z9Pq5bfsH61Ao+W8iakIzqg0QWNLyDdvf6jAppgta54yIatVOB OjUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=uY1/ylDyFsviT6XapDzVuCTqMf2QKuzO/x6kAiRsGL4=; b=IIzZRasHBBRPjRYBWBftRVxd+1PQqgmb5LN34vnVCTCCH7kstYkhWURC3womcq740+ xrPVJNZ1+Hdd/1VF2MhE8gwnk5GcTPVR2kKP4d+1xvq22O6qKXctqY7IScW3hPNOmmqd X5avLkcsz/FwFVNrHqm/r4Adi5kFmi8Ksk5u0CJZ5Hr1k79RI9SAAeP3yV92pGx4QBm9 IW/jocouCmJdmsnM62t56thOGrWUjmdOKNC9GgM/C1+mFLK/VBvkycZ/3yBadX4upcvX cArDnLF7d9aYSNCO4OnpTa5pEW6xiK1fgDi6yFRRpZDd0aOyz9npfHQP/VtuO58Aloe/ 3mXw== X-Gm-Message-State: APjAAAXcHb+YBu7sgwACVX3N4d6qpxg0E5kjug8TQwGOTga2OjeEKcXf /GU8oLX1uVQB7U5BJ5m0/WArI1qVCqQ= X-Google-Smtp-Source: APXvYqy7SG1NmOz6g0e0FLFmmDpjIjgok6UfafSJbToHJ6yvuBlc3IzEymgZ/r+YTxececYprhzdyw== X-Received: by 2002:adf:ea88:: with SMTP id s8mr6003594wrm.114.1568878436123; Thu, 19 Sep 2019 00:33:56 -0700 (PDT) Received: from localhost.localdomain ([2a01:e0a:f:6020:d555:8fca:a19c:222c]) by smtp.gmail.com with ESMTPSA id s12sm13300250wra.82.2019.09.19.00.33.54 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 19 Sep 2019 00:33:54 -0700 (PDT) From: Vincent Guittot To: linux-kernel@vger.kernel.org, mingo@redhat.com, peterz@infradead.org Cc: pauld@redhat.com, valentin.schneider@arm.com, srikar@linux.vnet.ibm.com, quentin.perret@arm.com, dietmar.eggemann@arm.com, Morten.Rasmussen@arm.com, hdanton@sina.com, Vincent Guittot Subject: [PATCH v3 0/8] sched/fair: rework the CFS load balance Date: Thu, 19 Sep 2019 09:33:31 +0200 Message-Id: <1568878421-12301-1-git-send-email-vincent.guittot@linaro.org> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Several wrong task placement have been raised with the current load balance algorithm but their fixes are not always straight forward and end up with using biased values to force migrations. A cleanup and rework of the load balance will help to handle such UCs and enable to fine grain the behavior of the scheduler for other cases. Patch 1 has already been sent separately and only consolidate asym policy in one place and help the review of the changes in load_balance. Patch 2 renames the sum of h_nr_running in stats. Patch 3 removes meaningless imbalance computation to make review of patch 4 easier. Patch 4 reworks load_balance algorithm and fixes some wrong task placement but try to stay conservative. Patch 5 add the sum of nr_running to monitor non cfs tasks and take that into account when pulling tasks. Patch 6 replaces runnable_load by load now that the signal is only used when overloaded. Patch 7 improves the spread of tasks at the 1st scheduling level. Patch 8 uses utilization instead of load in all steps of misfit task path. Patch 9 replaces runnable_load_avg by load_avg in the wake up path. Patch 10 optimizes find_idlest_group() that was using both runnable_load and load. This has not been squashed with previous patch to ease the review. Some benchmarks results based on 8 iterations of each tests: - small arm64 dual quad cores system tip/sched/core w/ this patchset improvement schedpipe 54981 +/-0.36% 55459 +/-0.31% (+0.97%) hackbench 1 groups 0.906 +/-2.34% 0.906 +/-2.88% (+0.06%) - large arm64 2 nodes / 224 cores system tip/sched/core w/ this patchset improvement schedpipe 125323 +/-0.98% 125624 +/-0.71% (+0.24%) hackbench -l (256000/#grp) -g #grp 1 groups 15.360 +/-1.76% 14.206 +/-1.40% (+8.69%) 4 groups 5.822 +/-1.02% 5.508 +/-6.45% (+5.38%) 16 groups 3.103 +/-0.80% 3.244 +/-0.77% (-4.52%) 32 groups 2.892 +/-1.23% 2.850 +/-1.81% (+1.47%) 64 groups 2.825 +/-1.51% 2.725 +/-1.51% (+3.54%) 128 groups 3.149 +/-8.46% 3.053 +/-13.15% (+3.06%) 256 groups 3.511 +/-8.49% 3.019 +/-1.71% (+14.03%) dbench 1 groups 329.677 +/-0.46% 329.771 +/-0.11% (+0.03%) 4 groups 931.499 +/-0.79% 947.118 +/-0.94% (+1.68%) 16 groups 1924.210 +/-0.89% 1947.849 +/-0.76% (+1.23%) 32 groups 2350.646 +/-5.75% 2351.549 +/-6.33% (+0.04%) 64 groups 2201.524 +/-3.35% 2192.749 +/-5.84% (-0.40%) 128 groups 2206.858 +/-2.50% 2376.265 +/-7.44% (+7.68%) 256 groups 1263.520 +/-3.34% 1633.143 +/-13.02% (+29.25%) tip/sched/core sha1: 0413d7f33e60 ('sched/uclamp: Always use 'enum uclamp_id' for clamp_id values') Changes since v2: - fix typo and reorder code - some minor code fixes - optimize the find_idles_group() Not covered in this patchset: - update find_idlest_group() to be more aligned with load_balance(). I didn't want to delay this version because of this update which is not ready yet - Better detection of overloaded and fully busy state, especially for cases when nr_running > nr CPUs. Vincent Guittot (8): sched/fair: clean up asym packing sched/fair: rename sum_nr_running to sum_h_nr_running sched/fair: remove meaningless imbalance calculation sched/fair: rework load_balance sched/fair: use rq->nr_running when balancing load sched/fair: use load instead of runnable load in load_balance sched/fair: evenly spread tasks when not overloaded sched/fair: use utilization to select misfit task sched/fair: use load instead of runnable load in wakeup path sched/fair: optimize find_idlest_group kernel/sched/fair.c | 805 +++++++++++++++++++++++++++------------------------- 1 file changed, 417 insertions(+), 388 deletions(-) -- 2.7.4