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=-20.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 15812C433B4 for ; Thu, 13 May 2021 13:19:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9BA061439 for ; Thu, 13 May 2021 13:19:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233999AbhEMNU7 (ORCPT ); Thu, 13 May 2021 09:20:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233950AbhEMNTF (ORCPT ); Thu, 13 May 2021 09:19:05 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06CC0C0613ED; Thu, 13 May 2021 06:17:37 -0700 (PDT) Date: Thu, 13 May 2021 13:17:29 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1620911850; 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=RutoUzK4xwcvEKA4oaKgdmga9hHsy5VloH/Y/0vKoPg=; b=LSAwjVnrg1sWf5PJwblqkOft8ZhT4tWBy+PYK+NJTdNF7F8QKmG6tJz9Qd8ugFigAtrG9L /+9G+7w6H+aprb6JTf40Vwy/pzv2/fLz/A1pgyC5Ou0uUchZFgeUISD0nqySjWqPGl2QVU ORrwChQbaTiqJ5f+a3iRCro8cZ0oGO0YWHl7deG8R8F8wCnpL5ZVnmii7ftV0dlowFNgPa UFAicPxyzX8mx/FJ4RVwlnwKp2oB9t6VBKJnZUeFMgU9x1LS/NJZby4wHVbPHSHLIZrH9X LcMcBgejJ/64Yxc4/tK7PaniAHTaDZoyZwmHfTt5AZZYqnGCuDh43Q+6VuyiiA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1620911850; 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=RutoUzK4xwcvEKA4oaKgdmga9hHsy5VloH/Y/0vKoPg=; b=t1LMsOTTcfRbmmObAv5MPcXzVInv5AtSJbvMHD/ISvIfzBJxjZRAo/8+532t02kYcsMxWL XXNOqAYYFR5d+cBg== From: "tip-bot2 for Yunfeng Ye" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: timers/nohz] tick/nohz: Conditionally restart tick on idle exit Cc: Yunfeng Ye , Frederic Weisbecker , Ingo Molnar , Peter Zijlstra , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20210512232924.150322-3-frederic@kernel.org> References: <20210512232924.150322-3-frederic@kernel.org> MIME-Version: 1.0 Message-ID: <162091184942.29796.4815200413212139734.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 timers/nohz branch of tip: Commit-ID: a5183862e76fdc25f36b39c2489b816a5c66e2e5 Gitweb: https://git.kernel.org/tip/a5183862e76fdc25f36b39c2489b816a5c66e2e5 Author: Yunfeng Ye AuthorDate: Thu, 13 May 2021 01:29:16 +02:00 Committer: Ingo Molnar CommitterDate: Thu, 13 May 2021 14:21:21 +02:00 tick/nohz: Conditionally restart tick on idle exit In nohz_full mode, switching from idle to a task will unconditionally issue a tick restart. If the task is alone in the runqueue or is the highest priority, the tick will fire once then eventually stop. But that alone is still undesired noise. Therefore, only restart the tick on idle exit when it's strictly necessary. Signed-off-by: Yunfeng Ye Signed-off-by: Frederic Weisbecker Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Link: https://lore.kernel.org/r/20210512232924.150322-3-frederic@kernel.org --- kernel/time/tick-sched.c | 42 +++++++++++++++++++++++++-------------- 1 file changed, 27 insertions(+), 15 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 828b091..05c1ce1 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -926,22 +926,28 @@ static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now) tick_nohz_restart(ts, now); } -static void tick_nohz_full_update_tick(struct tick_sched *ts) +static void __tick_nohz_full_update_tick(struct tick_sched *ts, + ktime_t now) { #ifdef CONFIG_NO_HZ_FULL int cpu = smp_processor_id(); - if (!tick_nohz_full_cpu(cpu)) + if (can_stop_full_tick(cpu, ts)) + tick_nohz_stop_sched_tick(ts, cpu); + else if (ts->tick_stopped) + tick_nohz_restart_sched_tick(ts, now); +#endif +} + +static void tick_nohz_full_update_tick(struct tick_sched *ts) +{ + if (!tick_nohz_full_cpu(smp_processor_id())) return; if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE) return; - if (can_stop_full_tick(cpu, ts)) - tick_nohz_stop_sched_tick(ts, cpu); - else if (ts->tick_stopped) - tick_nohz_restart_sched_tick(ts, ktime_get()); -#endif + __tick_nohz_full_update_tick(ts, ktime_get()); } static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) @@ -1209,18 +1215,24 @@ static void tick_nohz_account_idle_ticks(struct tick_sched *ts) #endif } -static void __tick_nohz_idle_restart_tick(struct tick_sched *ts, ktime_t now) +void tick_nohz_idle_restart_tick(void) { - tick_nohz_restart_sched_tick(ts, now); - tick_nohz_account_idle_ticks(ts); + struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); + + if (ts->tick_stopped) { + tick_nohz_restart_sched_tick(ts, ktime_get()); + tick_nohz_account_idle_ticks(ts); + } } -void tick_nohz_idle_restart_tick(void) +static void tick_nohz_idle_update_tick(struct tick_sched *ts, ktime_t now) { - struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); + if (tick_nohz_full_cpu(smp_processor_id())) + __tick_nohz_full_update_tick(ts, now); + else + tick_nohz_restart_sched_tick(ts, now); - if (ts->tick_stopped) - __tick_nohz_idle_restart_tick(ts, ktime_get()); + tick_nohz_account_idle_ticks(ts); } /** @@ -1252,7 +1264,7 @@ void tick_nohz_idle_exit(void) tick_nohz_stop_idle(ts, now); if (tick_stopped) - __tick_nohz_idle_restart_tick(ts, now); + tick_nohz_idle_update_tick(ts, now); local_irq_enable(); }