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 64FA8C49361 for ; Thu, 17 Jun 2021 12:23:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D0D1613BA for ; Thu, 17 Jun 2021 12:23:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232796AbhFQMZo (ORCPT ); Thu, 17 Jun 2021 08:25:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35990 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229714AbhFQMZn (ORCPT ); Thu, 17 Jun 2021 08:25:43 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D608C061574; Thu, 17 Jun 2021 05:23:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=igLdM5gAj1GNrpSUNqrKYdGwdRX8s5YgHkDIgpNMiug=; b=DGuEVNYKXCwUn4Knx7hLzxIXFC kBjt3R7Sgja4CX/H/5JZRU8/qxosfVuqv31b6plh7KyPaoJZj5xXeA00whiSQhEX3J3/JvaAQbWQ0 wH+vgBdhonn6rlAhUEbgKnbdPh+g6HmI7w678R0l1QJ7h7g/s1skWFLNUlDHFPjJRMjlHbKLw7/+L Xw2KrymU7hdx0F9jh3ZR70X10Wo32DSTtA3Hrpn5hBJftWZl+4SENYhSMnQnhE7qBfDu44F4F1axo ws9R+mfwUOJEzZjh7WgSCu8w68yUG+Ax4rPAXCrDhY2NdMOFGyq0ZIjjGjEknCgVjMZjWL7PihmWz Aqh1Y57g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1ltr2T-00978E-Ii; Thu, 17 Jun 2021 12:22:38 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 8B84E300204; Thu, 17 Jun 2021 14:22:28 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 62C292C885E37; Thu, 17 Jun 2021 14:22:28 +0200 (CEST) Date: Thu, 17 Jun 2021 14:22:28 +0200 From: Peter Zijlstra To: Viresh Kumar Cc: Ionela Voinescu , Rafael Wysocki , Sudeep Holla , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , linux-pm@vger.kernel.org, Qian Cai , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2 3/3] cpufreq: CPPC: Add support for frequency invariance Message-ID: References: <20210616124806.GA6495@arm.com> <20210617032416.r2gfp25xxvhc5t4x@vireshk-i7> <20210617103415.GA29877@arm.com> <20210617111936.cfjzoh6g5zvolaf5@vireshk-i7> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210617111936.cfjzoh6g5zvolaf5@vireshk-i7> Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Thu, Jun 17, 2021 at 04:49:36PM +0530, Viresh Kumar wrote: > Peter: Can you help here on this ? Lemme try to explain a bit here: > > We are starting an irq-work (in cppc cpufreq driver) from > scheduler_tick()->arch_scale_freq_tick(). What will happen if the driver doesn't > take care of CPU hotplug explicitly and make sure this work isn't queued again > from the next tick. > > Is it important for user to make sure it gets rid of the irq-work during hotplug > here ? irq-work is flushed on hotplug, see smpcfd_dying_cpu().