From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759187AbcAUJ0v (ORCPT ); Thu, 21 Jan 2016 04:26:51 -0500 Received: from mail-wm0-f48.google.com ([74.125.82.48]:33020 "EHLO mail-wm0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759173AbcAUJ0r (ORCPT ); Thu, 21 Jan 2016 04:26:47 -0500 Subject: Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings To: Peter Zijlstra References: <1453305636-22156-1-git-send-email-daniel.lezcano@linaro.org> <1453305636-22156-2-git-send-email-daniel.lezcano@linaro.org> <20160120190718.GS6357@twins.programming.kicks-ass.net> Cc: tglx@linutronix.de, rafael@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, nicolas.pitre@linaro.org, vincent.guittot@linaro.org From: Daniel Lezcano Message-ID: <56A0A454.7020606@linaro.org> Date: Thu, 21 Jan 2016 10:26:44 +0100 User-Agent: Mozilla/5.0 (X11; Linux i686; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20160120190718.GS6357@twins.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/20/2016 08:07 PM, Peter Zijlstra wrote: > On Wed, Jan 20, 2016 at 05:00:32PM +0100, Daniel Lezcano wrote: >> +++ b/kernel/irq/handle.c >> @@ -165,6 +165,7 @@ irqreturn_t handle_irq_event_percpu(struct irq_desc *desc) >> /* Fall through to add to randomness */ >> case IRQ_HANDLED: >> flags |= action->flags; >> + handle_irqtiming(irq, action->dev_id); >> break; >> >> default: > >> +++ b/kernel/irq/internals.h > >> +static inline void handle_irqtiming(unsigned int irq, void *dev_id) >> +{ >> + if (__irqtimings->handler) >> + __irqtimings->handler(irq, ktime_get(), dev_id); >> +} > > Here too, ktime_get() is daft. > > Also, you really want to take the timestamp _before_ we call the > handlers, not after, otherwise you mix in whatever variance exist in the > handler duration. Indeed. -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog