From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935053AbcATUXV (ORCPT ); Wed, 20 Jan 2016 15:23:21 -0500 Received: from www.linutronix.de ([62.245.132.108]:33574 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753129AbcATUXS (ORCPT ); Wed, 20 Jan 2016 15:23:18 -0500 Date: Wed, 20 Jan 2016 21:22:14 +0100 (CET) From: Thomas Gleixner To: Peter Zijlstra cc: Daniel Lezcano , rafael@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, nicolas.pitre@linaro.org, vincent.guittot@linaro.org Subject: Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings In-Reply-To: <20160120202014.GK6356@twins.programming.kicks-ass.net> Message-ID: 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> <20160120202014.GK6356@twins.programming.kicks-ass.net> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Jan 2016, Peter Zijlstra wrote: > On Wed, Jan 20, 2016 at 08:57:06PM +0100, Thomas Gleixner wrote: > > > Here too, ktime_get() is daft. > > > > What's the problem? ktime_xxx() itself or just the clock monotonic variant? > > > > On 99.9999% of the platforms ktime_get_mono_fast/raw_fast is not any slower > > than sched_clock(). The only case where sched_clock is faster is if your TSC > > is buggered and the box switches to HPET for timekeeping. > > The HPET thing, I just don't want to have to explain why this is so much > more expensive on some random weird machine, esp. since it really > doesn't matter. Fair enough.