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 9962FC38A02 for ; Fri, 28 Oct 2022 06:43:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229950AbiJ1Gnu (ORCPT ); Fri, 28 Oct 2022 02:43:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55380 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229890AbiJ1GmV (ORCPT ); Fri, 28 Oct 2022 02:42:21 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A606E1BA1DC; Thu, 27 Oct 2022 23:42:18 -0700 (PDT) Date: Fri, 28 Oct 2022 06:42:15 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1666939336; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=usVaBD3S4YKESMxSvqwWUJhemM6IgHEeu1Rml8DoK3g=; b=m1WDaRQtZ5VHxdeYKJnYlc3o+Msa4daA3HS/QOsLmos3mWybxIEMy616GRsxg2xohiD7Xw GAZnCdehrwfOYTlpNzLYK2utaya+aKGHvs/tDO4sdYw9RlWF2jTihUB9ic7KXsi29lJT71 FQs5gr7cIaF1abS49fL95oY0QPpcVcULt6aj2eHiKYn2QlEMjX3Q81I6u0lyFaSe4ivVHS QZq29NxkRDIQda7dAJbgjCHCuXeOZw/MJP7D30fqdoxg7wlaqw27PV9/BVAIWZNLlNYtVt 3+yws8huxJCoWmvMUVa1BNF5AYR9JkOdqX16b5vq/1VyKaechDJz14IgIqjpEg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1666939336; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=usVaBD3S4YKESMxSvqwWUJhemM6IgHEeu1Rml8DoK3g=; b=oQ1kM/QfI0A9SkdVbLmtATOyXzZTDUBbJi3ulYxmlga2nbrgW49pwrWwgJxBz0ksS9UoZG pyylGgoLhf9rgmBA== From: "tip-bot2 for Pierre Gondois" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched/fair: Check if prev_cpu has highest spare cap in feec() Cc: Pierre Gondois , "Peter Zijlstra (Intel)" , Dietmar Eggemann , Vincent Guittot , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20221006081052.3862167-2-pierre.gondois@arm.com> References: <20221006081052.3862167-2-pierre.gondois@arm.com> MIME-Version: 1.0 Message-ID: <166693933555.29415.8010748161395990501.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: ad841e569f5c88e3332b32a000f251f33ff32187 Gitweb: https://git.kernel.org/tip/ad841e569f5c88e3332b32a000f251f33ff32187 Author: Pierre Gondois AuthorDate: Thu, 06 Oct 2022 10:10:52 +02:00 Committer: Peter Zijlstra CommitterDate: Thu, 27 Oct 2022 11:01:20 +02:00 sched/fair: Check if prev_cpu has highest spare cap in feec() When evaluating the CPU candidates in the perf domain (pd) containing the previously used CPU (prev_cpu), find_energy_efficient_cpu() evaluates the energy of the pd: - without the task (base_energy) - with the task placed on prev_cpu (if the task fits) - with the task placed on the CPU with the highest spare capacity, prev_cpu being excluded from this set If prev_cpu is already the CPU with the highest spare capacity, max_spare_cap_cpu will be the CPU with the second highest spare capacity. On an Arm64 Juno-r2, with a workload of 10 tasks at a 10% duty cycle, when prev_cpu and max_spare_cap_cpu are both valid candidates, prev_spare_cap > max_spare_cap at ~82%. Thus the energy of the pd when placing the task on max_spare_cap_cpu is computed with no possible positive outcome 82% most of the time. Do not consider max_spare_cap_cpu as a valid candidate if prev_spare_cap > max_spare_cap. Signed-off-by: Pierre Gondois Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dietmar Eggemann Reviewed-by: Vincent Guittot Link: https://lore.kernel.org/r/20221006081052.3862167-2-pierre.gondois@arm.com --- kernel/sched/fair.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 919d016..4cc56c9 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7221,7 +7221,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) unsigned long cur_delta, max_spare_cap = 0; unsigned long rq_util_min, rq_util_max; unsigned long util_min, util_max; - bool compute_prev_delta = false; + unsigned long prev_spare_cap = 0; int max_spare_cap_cpu = -1; unsigned long base_energy; @@ -7283,18 +7283,19 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) if (cpu == prev_cpu) { /* Always use prev_cpu as a candidate. */ - compute_prev_delta = true; + prev_spare_cap = cpu_cap; } else if (cpu_cap > max_spare_cap) { /* * Find the CPU with the maximum spare capacity - * in the performance domain. + * among the remaining CPUs in the performance + * domain. */ max_spare_cap = cpu_cap; max_spare_cap_cpu = cpu; } } - if (max_spare_cap_cpu < 0 && !compute_prev_delta) + if (max_spare_cap_cpu < 0 && prev_spare_cap == 0) continue; eenv_pd_busy_time(&eenv, cpus, p); @@ -7302,7 +7303,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) base_energy = compute_energy(&eenv, pd, cpus, p, -1); /* Evaluate the energy impact of using prev_cpu. */ - if (compute_prev_delta) { + if (prev_spare_cap > 0) { prev_delta = compute_energy(&eenv, pd, cpus, p, prev_cpu); /* CPU utilization has changed */ @@ -7313,7 +7314,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) } /* Evaluate the energy impact of using max_spare_cap_cpu. */ - if (max_spare_cap_cpu >= 0) { + if (max_spare_cap_cpu >= 0 && max_spare_cap > prev_spare_cap) { cur_delta = compute_energy(&eenv, pd, cpus, p, max_spare_cap_cpu); /* CPU utilization has changed */