From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752083AbaEZJ1Q (ORCPT ); Mon, 26 May 2014 05:27:16 -0400 Received: from mout.kundenserver.de ([212.227.17.13]:56015 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751782AbaEZJ1P (ORCPT ); Mon, 26 May 2014 05:27:15 -0400 From: Arnd Bergmann To: linux-arm-kernel@lists.infradead.org Cc: minyard@acm.org, linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, Corey Minyard Subject: Re: [PATCH] arm: Set hardirq tracing to on when idling Date: Mon, 26 May 2014 11:26:42 +0200 Message-ID: <4559339.apo3Fd10HK@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.11.0-18-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1401045323-7116-1-git-send-email-minyard@acm.org> References: <1401045323-7116-1-git-send-email-minyard@acm.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V02:K0:QDXui5PdB9udEBpfwxGDNHonM+0L1lQDA7vGCl2YdcA MHb16WAT34/kSFDJ91lcuJtOSOE51eBR3j4ZJ/UCugcIulHP4n KQ+8KfHQeS6iXUmWZ1aI8bY9CYNRJseX5O2Y9mAUJY2JL3/if1 ZW93H8Q3vX7Qc4AsaELBcxC8nHc6hotA7xtA6Ym+yF8gNLQOg4 EE/Uf4CiSY8X37vKpNOhz3+KWr3OSEK4KljVM1E4qZp5PavRKr 2KlBqXCpsWM2D8DGA1Yls8xBD5xPV19pBcP723xwwaVfsmdhrP qugMVjeWCG5jsDEdFq5j9NrtrIW/W/S73ak8PzrqKZ131hZRXb GB05lCy/MHbL+s3FDuA0= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sunday 25 May 2014 14:15:23 minyard@acm.org wrote: > From: Corey Minyard > > The CPU will go to idle with interrupts off, but the interrupts > will wake up the idle. This was causing very long irqsoff trace > values because, basically, the whole idle time was traces with > irqs off, even though they weren't really off. Rework the idle > code to turn hardirq tracing to on befor calling idle. > > Signed-off-by: Corey Minyard > --- > arch/arm/kernel/process.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > I'm not sure this is correct for all ARM boards, but it fixes the > issue for the Vexpress board I have. No more 4 second irqsoff > times. If this patch is correct for ARM, I wonder if it should be done in architecture independent code instead. Do you see the same thing on x86? If not, do you know what's different? It seems like the right thing to do, I just don't understand why nobody hit this before. Arnd