From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Andrzej Siewior Subject: Re: cpufreq + PREEMPT_RT_FULL give bad context sleeping BUG Date: Thu, 25 Apr 2013 17:23:34 +0200 Message-ID: <20130425152334.GA5561@linutronix.de> References: <20130323013003.GU11538@uudg.org> <514DE3BF.5010800@gentil.com> <20130326205107.GB14220@linutronix.de> <20130326213356.GC14220@linutronix.de> <51530EE4.1040600@gentil.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Thomas Gleixner , Linus Walleij , Santosh Shilimkar , Rob Herring , linux-rt-users To: Gregoire Gentil Return-path: Received: from www.linutronix.de ([62.245.132.108]:44775 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932596Ab3DYPXj convert rfc822-to-8bit (ORCPT ); Thu, 25 Apr 2013 11:23:39 -0400 Content-Disposition: inline In-Reply-To: <51530EE4.1040600@gentil.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: * Gregoire Gentil | 2013-03-27 08:23:16 [-0700]: >>>>[0] http://dev.omapzoom.org/?p=3Dintegration/kernel-ubuntu.git;a=3D= blob;f=3Darch/arm/plat-omap/clock.c;h=3D8c0e8fe2c5c51673e41e4304194d922= dbfaedf38;hb=3D3e1c9f139425663ceee48f92e8d3f23158580334 >>> >>>Yeah, it's that way in mainline as well. >> >>I meant, that the mutex is taken. So yes, this will cause a warning i= n >>!RT too. >Hello, > >So what could be a tentative solution? Could you advise what I could t= ry? The easy way would be to get the clockfw_lock lock changed into a raw_spinlock_t and fix clk_get_rate() and others. If the lock is taken for a long time it will increase you latency. You try to check if it is possible to defer twd_update_frequency() to a workqueue and execute it later and not directly from the interrupt. On the other hand you might want simply disable cpufreq. If you have a certain latency and the cpu frequency goes down because the system is idle then you latency will increase. Basicaly an idle machine will wors= e latency than a busy one. You probably don't want this. > >Many thanks in advance, > >Gr=C3=A9goire Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-rt-user= s" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html