From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753424AbaE0Tjd (ORCPT ); Tue, 27 May 2014 15:39:33 -0400 Received: from mout.kundenserver.de ([212.227.17.13]:61693 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752142AbaE0Tjb (ORCPT ); Tue, 27 May 2014 15:39:31 -0400 From: Arnd Bergmann To: Stephen Boyd Cc: linux-arm-kernel@lists.infradead.org, Corey Minyard , linux-rt-users@vger.kernel.org, minyard@acm.org, linux-kernel@vger.kernel.org, Stanislav Meduna Subject: Re: [PATCH] arm: Set hardirq tracing to on when idling Date: Tue, 27 May 2014 21:39:22 +0200 Message-ID: <10128642.DD2TJ8Ps9I@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.11.0-18-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <5384E892.90808@codeaurora.org> References: <1401045323-7116-1-git-send-email-minyard@acm.org> <6082113.tHepRBe99K@wuerfel> <5384E892.90808@codeaurora.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V02:K0:odLtXBYWOPxAkuCYem7vArz32bjaoY+/IuFzcPf61Hp 6SsFAfDqKwzC1cGF5AoY6m8ZtEQ7DQENJ0DIdxHPaaAH0VENCB Sh7O7nCJae9KUDZh4JDXmpsm8nMqIuaTq5XdNROqmQdCAunhil 8SbDhwtjL03NF1rhQ2pErH9TqNuj+qj312ntBzAvE0NUxqd/Cr 4vTWlJJNZvtk4wb1VyadBNgV1qquNPUkp4pGYyJCrgV3HEsXwQ 1Ho3a4OrZqVVr1WAxbe2ADW3QIwPACqv/DUxL5qb0lXgFa7RDx itTaJ6D+GqJcgGH0T8/8uUbofaVpAvr9kaoppSY24ViCRubqLx jqzfk9cG8v/2IGK3nLNU= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 27 May 2014 12:33:38 Stephen Boyd wrote: > On 05/27/14 12:27, Arnd Bergmann wrote: > > On Tuesday 27 May 2014 11:53:59 Stephen Boyd wrote: > >> On 05/27/14 11:49, Arnd Bergmann wrote: > >>> You also commented in that thread about stop_critical_timings()/ > >>> start_critical_timings(). Corey, can you look at that, too? I > >>> think it's designed to avoid the issue you are seeing but > >>> for some reason doesn't. > >> I sent a patch last week to "solve" this problem. I'm not sure if it's > >> right but it works for me. > >> > >> https://lkml.org/lkml/2014/5/19/607 > > I think that one was also wrong, as the intention of the existing > > stop_critical_timings() function is already to do the same that > > Corey's patch does, i.e. stop the trace before we go to idle as > > if we were turning IRQs on. > > stop_critical_timings() is called in the generic idle loop. It looks > like stop_critical_timings() just isn't written correctly. All it does > is turn off the tracer, but it doesn't prevent future calls to > spinlocks, etc. from causing the tracer to turn on again between calls > to stop/start_critical_timings(). It seems better to prevent any more > tracing from happening between a call to stop_critical_timings() and > start_critical_timings() so we don't have to litter calls to that > function throughout the idle path. But are there any such calls in the idle function? I understand what you are doing in your patch, but I don't see why you have to actually do it. Arnd