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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 77056C4361B for ; Wed, 16 Dec 2020 10:11:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18F4B2313B for ; Wed, 16 Dec 2020 10:11:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726314AbgLPKKz (ORCPT ); Wed, 16 Dec 2020 05:10:55 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:38730 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726010AbgLPKKz (ORCPT ); Wed, 16 Dec 2020 05:10:55 -0500 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1608113413; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=/DpnWG2VZiw1n/B+lrW0oIhS8lbEl9jOP8otn08LVYo=; b=jqHXoCbIPJ064ZTStJP8Y63JgOyPyTchpeMy2rILmyzmeFW4Bhaoqw+g1e6+9sRlkTrRWq pl+2uDX3pJfQ7hqFPDeUL7jiUQU6p6hPV0d+3dGkuSGY+y5QUUxxAkJ74hmMUxvqp6YuOv kwDrs6dnRdDVrVnK7LSNUqdTX3GogMndyG+Na9yHXVIAKw2DF6AvSZonOjplqqqNx2TDKw L9Vr0//AoUOJ0BzmjlzUk3VpbivdIs2PRrjWWyFzEkolrGsfIxgueWAdiYZXzgsWVwF+br Lhfu0KBGcK+5c10yvxB0jiVSFcaISMS3u6GYRtTYe7B34HwZbqQ7ZsWla4G2eg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1608113413; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=/DpnWG2VZiw1n/B+lrW0oIhS8lbEl9jOP8otn08LVYo=; b=kMvDAoh2HG6BGW/U9DzwYN+N6ux2FUz1x6p/PPMsN0AssxV7JJw6S9RtpWVjcvaWvXPBmN 2X4yYbOuoAWmFQAw== To: Peter Zijlstra Cc: Steven Rostedt , Anna-Maria Behnsen , linux-kernel@vger.kernel.org, Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira Subject: Re: [PATCH] sched: Prevent raising SCHED_SOFTIRQ when CPU is !active In-Reply-To: <20201216081904.GK3040@hirez.programming.kicks-ass.net> References: <20201215104400.9435-1-anna-maria@linutronix.de> <20201215111806.GF3040@hirez.programming.kicks-ass.net> <20201215093415.5b2898ef@gandalf.local.home> <20201215150529.GI3040@hirez.programming.kicks-ass.net> <87mtyft0r2.fsf@nanos.tec.linutronix.de> <20201216081904.GK3040@hirez.programming.kicks-ass.net> Date: Wed, 16 Dec 2020 11:10:12 +0100 Message-ID: <87zh2erri3.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 16 2020 at 09:19, Peter Zijlstra wrote: > On Tue, Dec 15, 2020 at 06:52:49PM +0100, Thomas Gleixner wrote: >> I might be missing something, but how is the CPU which runs the pinned >> kernel thread, i.e. the hotplug thread, supposed to go idle between the >> two calls? > > Take a mutex or something other daft. My disabling preemption around it > we basically assert the two functions are non-blocking and none of that > cruft matters. That'd be really daft, but yes we can do that for paranoia sake. Thanks, tglx