From patchwork Wed May 9 10:35:24 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Viresh Kumar X-Patchwork-Id: 10389075 X-Patchwork-Delegate: rjw@sisk.pl Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 91DBC60353 for ; Wed, 9 May 2018 10:35:38 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8434E28A69 for ; Wed, 9 May 2018 10:35:38 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 78E5328A84; Wed, 9 May 2018 10:35:38 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2598228A69 for ; Wed, 9 May 2018 10:35:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934598AbeEIKfa (ORCPT ); Wed, 9 May 2018 06:35:30 -0400 Received: from mail-pl0-f66.google.com ([209.85.160.66]:36215 "EHLO mail-pl0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934246AbeEIKf2 (ORCPT ); Wed, 9 May 2018 06:35:28 -0400 Received: by mail-pl0-f66.google.com with SMTP id v24-v6so4051583plo.3 for ; Wed, 09 May 2018 03:35:28 -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:in-reply-to:references; bh=5SzBrZbubm4x8fwQ1rrcy/99XzSEH3HZBVnWEOpEmFA=; b=RinBfvN36+W/1OjvAgeeOKjOuTBfMWEMXxw/cRiTVNVZ2eOFbYLcdthgG+setYzkQB 89Nl7qL9Q8nobzKvp5u16hQ2bpMfz4NGI03LTK068jY5F/5mN3FSFmjYgiHvjvl9hcH7 t9GDREUGm6b081Xokhc2TPkFitmlvA1/OBqsM= 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:in-reply-to :references; bh=5SzBrZbubm4x8fwQ1rrcy/99XzSEH3HZBVnWEOpEmFA=; b=YHYKr4Sp8iMLfBHCahW6KkiJ1k+dzyO7xv9Q4oDEvloImOvU2OZbop0D7NNskWUain lUtW4Qc6E1H4svBiNru7Dtx6bZvxolH/NNSDJKgbTe7GPLw5/JgF73aUlL1PiJClqmp7 GUD8YkHnqgvzWMNuAc0m6UkKrKt9yYq6JJSIJEMjZKyWnTPe7TfaB9QsoSvUxeKTS1IP C2vKvSaiPGKCmdAHly7cDmQJ2Vfyw5rm1Zu5BDoa+I5WFgWh3YxPnm2CZmZZsw34raMB tnP9xlRgDbjmOa3ms7o/AkT/vdyhAmsnHOtproYpm5HmRtSg9ns+77IpS9KEldnOQV+j NYDg== X-Gm-Message-State: ALQs6tCgDwCi9/4q392Gd5b2+U40ygy4p+QQe0NSjalGl3b50NC2NdZq pZxWXVJTmN0NfRaEGFe5cdLVKg== X-Google-Smtp-Source: AB8JxZqRvJ/V5qsRzWtxazZkwquQyK29Ed+U9lBfPivbtif2cDVeP3I5k+hPb47Z5AMtLSQEDrJvhw== X-Received: by 2002:a17:902:6903:: with SMTP id j3-v6mr24128996plk.313.1525862128260; Wed, 09 May 2018 03:35:28 -0700 (PDT) Received: from localhost ([122.167.163.112]) by smtp.gmail.com with ESMTPSA id u68sm15231152pfu.32.2018.05.09.03.35.27 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 09 May 2018 03:35:27 -0700 (PDT) From: Viresh Kumar To: Rafael Wysocki , Ingo Molnar , Peter Zijlstra Cc: Viresh Kumar , linux-pm@vger.kernel.org, Vincent Guittot , linux-kernel@vger.kernel.org Subject: [PATCH V2] sched/schedutil: Don't set next_freq to UINT_MAX Date: Wed, 9 May 2018 16:05:24 +0530 Message-Id: X-Mailer: git-send-email 2.15.0.194.g9af6a3dea062 In-Reply-To: <2276196.ev9rMjHTR0@aspire.rjw.lan> References: <2276196.ev9rMjHTR0@aspire.rjw.lan> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The schedutil driver sets sg_policy->next_freq to UINT_MAX on certain occasions to discard the cached value of next freq: - In sugov_start(), when the schedutil governor is started for a group of CPUs. - And whenever we need to force a freq update before rate-limit duration, which happens when: - there is an update in cpufreq policy limits. - Or when the utilization of DL scheduling class increases. In return, get_next_freq() doesn't return a cached next_freq value but recalculates the next frequency instead. But having special meaning for a particular value of frequency makes the code less readable and error prone. We recently fixed a bug where the UINT_MAX value was considered as valid frequency in sugov_update_single(). All we need is a flag which can be used to discard the value of sg_policy->next_freq and we already have need_freq_update for that. Lets reuse it instead of setting next_freq to UINT_MAX. Signed-off-by: Viresh Kumar Reviewed-by: Joel Fernandes (Google) --- V2: - Rebased over the fix sent by Rafael lkml.kernel.org/r/2276196.ev9rMjHTR0@aspire.rjw.lan - Remove the additional check from sugov_update_single() as well. - This is for 4.18 now instead of stable kernels. kernel/sched/cpufreq_schedutil.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index e23e84724f39..daaca23697dc 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -95,15 +95,8 @@ static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time) if (sg_policy->work_in_progress) return false; - if (unlikely(sg_policy->need_freq_update)) { - sg_policy->need_freq_update = false; - /* - * This happens when limits change, so forget the previous - * next_freq value and force an update. - */ - sg_policy->next_freq = UINT_MAX; + if (unlikely(sg_policy->need_freq_update)) return true; - } delta_ns = time - sg_policy->last_freq_update_time; @@ -165,8 +158,10 @@ static unsigned int get_next_freq(struct sugov_policy *sg_policy, freq = (freq + (freq >> 2)) * util / max; - if (freq == sg_policy->cached_raw_freq && sg_policy->next_freq != UINT_MAX) + if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update) return sg_policy->next_freq; + + sg_policy->need_freq_update = false; sg_policy->cached_raw_freq = freq; return cpufreq_driver_resolve_freq(policy, freq); } @@ -305,8 +300,7 @@ static void sugov_update_single(struct update_util_data *hook, u64 time, * Do not reduce the frequency if the CPU has not been idle * recently, as the reduction is likely to be premature then. */ - if (busy && next_f < sg_policy->next_freq && - sg_policy->next_freq != UINT_MAX) { + if (busy && next_f < sg_policy->next_freq) { next_f = sg_policy->next_freq; /* Reset cached freq as next_freq has changed */ @@ -671,7 +665,7 @@ static int sugov_start(struct cpufreq_policy *policy) sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC; sg_policy->last_freq_update_time = 0; - sg_policy->next_freq = UINT_MAX; + sg_policy->next_freq = 0; sg_policy->work_in_progress = false; sg_policy->need_freq_update = false; sg_policy->cached_raw_freq = 0;