Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759985AbXHUGq3 (ORCPT ); Tue, 21 Aug 2007 02:46:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755714AbXHUGqU (ORCPT ); Tue, 21 Aug 2007 02:46:20 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:59250 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756742AbXHUGqU (ORCPT ); Tue, 21 Aug 2007 02:46:20 -0400 Date: Mon, 20 Aug 2007 23:45:23 -0700 (PDT) From: Linus Torvalds To: Arjan van de Ven cc: David Brownell , Michal Piotrowski , linux-usb-devel@lists.sourceforge.net, Greg KH , LKML , "Stuart_Hayes@Dell.com" , Andrew Morton , Daniel Exner Subject: Re: [linux-usb-devel] [4/4] 2.6.23-rc3: known regressions In-Reply-To: <1187677685.2676.12.camel@laptopd505.fenrus.org> Message-ID: References: <46C098FD.1030601@googlemail.com> <200708202102.58508.david-b@pacbell.net> <200708202148.45575.david-b@pacbell.net> <1187675488.2676.3.camel@laptopd505.fenrus.org> <1187676254.2676.6.camel@laptopd505.fenrus.org> <1187677685.2676.12.camel@laptopd505.fenrus.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1810 Lines: 49 On Mon, 20 Aug 2007, Arjan van de Ven wrote: > > On Mon, 2007-08-20 at 23:26 -0700, Linus Torvalds wrote: > > > > On Mon, 20 Aug 2007, Arjan van de Ven wrote: > > > > > > untested patch to add this to cpufreq; this is probably a good idea in > > > general even if using the latency framework doesn't end up being used > > > for fixing this regression... > > > > > > > > > --- linux-2.6.23-rc2/drivers/cpufreq/cpufreq.c.org 2007-08-20 22:58:32.000000000 -0700 > > > +++ linux-2.6.23-rc2/drivers/cpufreq/cpufreq.c 2007-08-20 23:02:21.000000000 -0700 > > > @@ -1604,6 +1604,12 @@ static int __cpufreq_set_policy(struct c > > > if (ret) > > > goto error_out; > > > > > > + > > > + if (system_latency_constraint() < policy->cpuinfo.transition_latency) { > > > > That looks broken. "system_latency_constraint()" is in us, but > > transition_latency is in ns, afaik. > > > > But adding a "/ 1000" to turn the ns into us, and it migth even work. > > > eh woops yes indeed. > Shows me for not testing; I'll do that tomorrow when I'm more awake Side note: I think we migth want to also have some way of telling the user *why* we're not doing frequency changes. Maybe as simple as a rate-limited printk() or something. Otherwise, we'll easily be in a situation where some poor sod ends up running constantly at lowest frequency, and no way of even seeing why. Which sounds like a debugging nightmare. If the kernel spits out the occasional warning about the latency violation, at least we get notified about there being potential problems. Linus - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/