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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B652DC433EF for ; Tue, 19 Oct 2021 12:35:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 90D8D61260 for ; Tue, 19 Oct 2021 12:35:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235616AbhJSMh6 (ORCPT ); Tue, 19 Oct 2021 08:37:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38542 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230231AbhJSMh4 (ORCPT ); Tue, 19 Oct 2021 08:37:56 -0400 Received: from mail-wr1-x42b.google.com (mail-wr1-x42b.google.com [IPv6:2a00:1450:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0FB19C06161C for ; Tue, 19 Oct 2021 05:35:44 -0700 (PDT) Received: by mail-wr1-x42b.google.com with SMTP id k7so47276715wrd.13 for ; Tue, 19 Oct 2021 05:35:43 -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=6ESHQOo9KySzj+CoCPClGyaxb6lsjeZdTqttkXRUbsM=; b=J1eKkiRReI/jo4nvnXN28MxZt0b0JOxrEmv1OZThkjU2bxXVlFeN81h99SP4gqfPuJ bzzeWrmZwWkTx5NNAdL4CJf/WC8Ux5tfQNnYbM4F0zsm2GxwUehFYK3Z7Tv7vjzP0dJl m2osxOIktXW6oUxwpljAdrGeXdKBuB0LHlOidXjOl1InnarZmNcAR4DIGnd14DFKibyh JLIvP2G2sogOtBQI1U9emjRDZE3yxUock6JptUmDtCeMoROgmsjN13Coavl0WOdwUtpu HmN1mxN/pJpfBKPputFBvsaFYommewU3b/GyQ2bX3GAbpnJf1G6cnmxIBxFp7ej7WvKK 5I4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=6ESHQOo9KySzj+CoCPClGyaxb6lsjeZdTqttkXRUbsM=; b=W9cgXSypTeWjdWll1DcwCCZwKT4WERsMhMB/V69szg8KXiIQFOjER5s+WGfPehRATs DLmTCLtG56nYo0BIwvuI8N8nfNqaegqF2PMRv99pMTg6/6BMS48Xc7/9L2DPSS1V81L7 Lpm3IKM02dNlk2wvTRFsTY6KWvUQnzfQnHkiKWBXdVeYhhE5t8qC5bylMKAAgpLXj8x9 TXFNsuaGUkeCC4Rg7EPKQc2Wgm60gXa26+MnywF16rFen1aWEmK0Z+kpcPdvEtglsULb Qg/QtjDKPLH1oKDfmynN6yf7fbLgehF4yvrfivUbPj4E6T11bobmM0TVYb11w1VBfPLW lRXA== X-Gm-Message-State: AOAM530C76zsNTPSTvZBGDWgIcO5oMjQ94AX4Vc6ah8YX1T2T1ti1m66 sUhxMTw/2vGlTpxjs2xq21WhRA== X-Google-Smtp-Source: ABdhPJxtcUBehLH/kWC+8xC+IwhQqMeTHFzatk9gewxEumfqCdo5aNk8BMYKT/CJwtGY4Tx3vfHaIg== X-Received: by 2002:adf:8bcf:: with SMTP id w15mr44267036wra.144.1634646942550; Tue, 19 Oct 2021 05:35:42 -0700 (PDT) Received: from localhost.localdomain ([2a01:e0a:f:6020:6dc7:9883:a79c:5be9]) by smtp.gmail.com with ESMTPSA id p18sm15263683wrn.41.2021.10.19.05.35.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Oct 2021 05:35:41 -0700 (PDT) From: Vincent Guittot To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, linux-kernel@vger.kernel.org, tim.c.chen@linux.intel.com Cc: Vincent Guittot Subject: [PATCH v3 0/5] Improve newidle lb cost tracking and early abort Date: Tue, 19 Oct 2021 14:35:32 +0200 Message-Id: <20211019123537.17146-1-vincent.guittot@linaro.org> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patchset updates newidle lb cost tracking and early abort: The time spent running update_blocked_averages is now accounted in the 1st sched_domain level. This time can be significant and move the cost of newidle lb above the avg_idle time. The decay of max_newidle_lb_cost is modified to start only when the field has not been updated for a while. Recent update will not be decayed immediatlybut only after a while. The condition of an avg_idle lower than sysctl_sched_migration_cost has been removed as the 500us value is quite large and prevent opportunity to pull task on the newly idle CPU for at least 1st domain levels. Monitoring sd->max_newidle_lb_cost on cpu0 of a Arm64 system THX2 (2 nodes * 28 cores * 4 cpus) during the benchmarks gives the following results: min avg max SMT: 1us 33us 273us - this one includes the update of blocked load MC: 7us 49us 398us NUMA: 10us 45us 158us Some results for hackbench -l $LOOPS -g $group : group tip/sched/core + this patchset 1 15.189(+/- 2%) 14.987(+/- 2%) +1% 4 4.336(+/- 3%) 4.322(+/- 5%) +0% 16 3.654(+/- 1%) 2.922(+/- 3%) +20% 32 3.209(+/- 1%) 2.919(+/- 3%) +9% 64 2.965(+/- 1%) 2.826(+/- 1%) +4% 128 2.954(+/- 1%) 2.993(+/- 8%) -1% 256 2.951(+/- 1%) 2.894(+/- 1%) +2% tbench and reaim have not shown any difference Change since v2: - Update and decay of sd->last_decay_max_lb_cost are gathered in update_newidle_cost(). The behavior remains almost the same except that the decay can happen during newidle_balance now. Tests results haven't shown any differences I haven't modified rq->max_idle_balance_cost. It acts as the max value for avg_idle and prevents the latter to reach high value during long idle phase. Moving on an IIR filter instead, could delay the convergence of avg_idle to a reasonnable value that reflect current situation. - Added a minor cleanup of newidle_balance Change since v1: - account the time spent in update_blocked_averages() in the 1st domain - reduce number of call of sched_clock_cpu() - change the way max_newidle_lb_cost is decayed. Peter suggested to use a IIR but keeping a track of the current max value gave the best result - removed the condition (this_rq->avg_idle < sysctl_sched_migration_cost) as suggested by Peter Vincent Guittot (5): sched/fair: Account update_blocked_averages in newidle_balance cost sched/fair: Skip update_blocked_averages if we are defering load balance sched/fair: Wait before decaying max_newidle_lb_cost sched/fair: Remove sysctl_sched_migration_cost condition sched/fair: cleanup newidle_balance include/linux/sched/topology.h | 2 +- kernel/sched/fair.c | 65 ++++++++++++++++++++++------------ kernel/sched/topology.c | 2 +- 3 files changed, 45 insertions(+), 24 deletions(-) -- 2.17.1