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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 E1C4DC83013 for ; Tue, 1 Dec 2020 11:41:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8AE3B2086A for ; Tue, 1 Dec 2020 11:41:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="XwwB5LDY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388214AbgLALlL (ORCPT ); Tue, 1 Dec 2020 06:41:11 -0500 Received: from mail.kernel.org ([198.145.29.99]:50220 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730664AbgLALlK (ORCPT ); Tue, 1 Dec 2020 06:41:10 -0500 Received: from localhost (i15-lef02-th2-89-83-198-20.ft.lns.abo.bbox.fr [89.83.198.20]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6479A2084C; Tue, 1 Dec 2020 11:40:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606822830; bh=iYw6lui6dDC7149K260wkncZlQ2NhDrpOG50v8ppeuc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XwwB5LDYujcEWEQX5bJAoiD9ry3JwtOpEtLoy/773Jf/NjiHpC8gZEmPzblT9dYaG JPNj/WuZ+HkVZrtA3VIi+Ey9bI9DPDVSeiuKzPq3g3cYv+WeeK8dHaGP/w4Hh8bxeb TfQ9Vz41GrJqSKzFNWtTKV1yj4ZFdVu4ASdGAlbY= Date: Tue, 1 Dec 2020 12:40:26 +0100 From: Frederic Weisbecker To: Thomas Gleixner Cc: Peter Zijlstra , LKML , Tony Luck , Vasily Gorbik , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Christian Borntraeger , Fenghua Yu , Heiko Carstens Subject: Re: [PATCH 4/5] irqtime: Move irqtime entry accounting after irq offset incrementation Message-ID: <20201201114026.GB72897@lothringen> References: <20201201001226.65107-1-frederic@kernel.org> <20201201001226.65107-5-frederic@kernel.org> <20201201092011.GS2414@hirez.programming.kicks-ass.net> <87im9lhibd.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87im9lhibd.fsf@nanos.tec.linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 01, 2020 at 12:33:26PM +0100, Thomas Gleixner wrote: > On Tue, Dec 01 2020 at 10:20, Peter Zijlstra wrote: > > On Tue, Dec 01, 2020 at 01:12:25AM +0100, Frederic Weisbecker wrote: > > Why not something like: > > > > void irqtime_account_irq(struct task_struct *curr, unsigned int offset) > > { > > struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime); > > unsigned int pc = preempt_count() - offset; > > s64 delta; > > int cpu; > > > > if (!sched_clock_irqtime) > > return; > > > > cpu = smp_processor_id(); > > delta = sched_clock_cpu(cpu) - irqtime->irq_start_time; > > irqtime->irq_start_time += delta; > > > > /* > > * We do not account for softirq time from ksoftirqd here. > > * We want to continue accounting softirq time to ksoftirqd thread > > * in that case, so as not to confuse scheduler with a special task > > * that do not consume any time, but still wants to run. > > */ > > if (pc & HARDIRQ_MASK) > > irqtime_account_delta(irqtime, delta, CPUTIME_IRQ); > > else if ((pc & SOFTIRQ_OFFSET) && curr != this_cpu_ksoftirqd()) > > irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ); > > } > > Why not making all of this explicit instead of these conditionals? Hmm, I'm not sure I get what you suggest? Thanks.