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 59112C4361B for ; Wed, 16 Dec 2020 08:20:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0407223356 for ; Wed, 16 Dec 2020 08:20:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725915AbgLPIUG (ORCPT ); Wed, 16 Dec 2020 03:20:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725274AbgLPIUF (ORCPT ); Wed, 16 Dec 2020 03:20:05 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D53FEC0613D6 for ; Wed, 16 Dec 2020 00:19:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=tvyQmXVAfz/2Lo0TusD+HjU56ZhaWL40OiopO9KNh5E=; b=bJZuXljBeUOrUVDuXapuedCsWh zEcQdPTTbqJfErYR6TjMoTW+obBa/GOqhSjrYQQVpRANcqrzhd9DwaPQ10ZihOypr3Auci0Vl06Wr PiXfLVkFmMiM5R2k20KvnjLR/D09v+zqTU9Fl//p5BTCMJONb73gZkC3i1HkYb6FopgwnE0EepV1I 0wpwiYuZlKTL0NlNGWtWW+Puf2oXlimaItx/Z83/yDLfSjZxZjmfUwQaAu61bPABnQguV8atODOj9 lQx6rtRilr+uaAPOvWm6CmujRU+n2FtruMnjUhLE70dSsE+AQPUeN2xK3epjumPm0DogPCybUwY0O v0t6909Q==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kpS1c-000410-Os; Wed, 16 Dec 2020 08:19:09 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 18A17304D58; Wed, 16 Dec 2020 09:19:05 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id EC8B2203C64AC; Wed, 16 Dec 2020 09:19:04 +0100 (CET) Date: Wed, 16 Dec 2020 09:19:04 +0100 From: Peter Zijlstra To: Thomas Gleixner 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 Message-ID: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87mtyft0r2.fsf@nanos.tec.linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.