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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 9379FC18E5B for ; Tue, 17 Mar 2020 10:56:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 76F6F20658 for ; Tue, 17 Mar 2020 10:56:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726703AbgCQK4j (ORCPT ); Tue, 17 Mar 2020 06:56:39 -0400 Received: from foss.arm.com ([217.140.110.172]:35000 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726666AbgCQK4f (ORCPT ); Tue, 17 Mar 2020 06:56:35 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 35ECC1FB; Tue, 17 Mar 2020 03:56:35 -0700 (PDT) Received: from e113632-lin (e113632-lin.cambridge.arm.com [10.1.194.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D9F4D3F534; Tue, 17 Mar 2020 03:56:33 -0700 (PDT) References: <20200311202625.13629-1-daniel.lezcano@linaro.org> User-agent: mu4e 0.9.17; emacs 26.3 From: Valentin Schneider To: Daniel Lezcano Cc: peterz@infradead.org, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, linux-kernel@vger.kernel.org, qais.yousef@arm.com Subject: Re: [PATCH V2] sched: fair: Use the earliest break even In-reply-to: <20200311202625.13629-1-daniel.lezcano@linaro.org> Date: Tue, 17 Mar 2020 10:56:11 +0000 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Daniel, One more comment on the break even itself, ignoring the rest: On Wed, Mar 11 2020, Daniel Lezcano wrote: > diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c > index b743bf38f08f..3342e7bae072 100644 > --- a/kernel/sched/idle.c > +++ b/kernel/sched/idle.c > @@ -19,7 +19,13 @@ extern char __cpuidle_text_start[], __cpuidle_text_end[]; > */ > void sched_idle_set_state(struct cpuidle_state *idle_state) > { > - idle_set_state(this_rq(), idle_state); > + struct rq *rq = this_rq(); > + > + idle_set_state(rq, idle_state); > + > + if (idle_state) > + idle_set_break_even(rq, ktime_get_ns() + > + idle_state->exit_latency_ns); I'm not sure I follow why we go for entry time + exit latency. If this is based on the minimum residency, shouldn't this be something depending on the entry latency? i.e. something like break_even = now + entry_latency + idling_time \_________________________/ min-residency or am I missing something? > } > > static int __read_mostly cpu_idle_force_poll;