From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: OnDemand governor vs. work queue Date: Thu, 26 May 2005 07:26:39 +1000 Message-ID: <1117056399.5076.0.camel@gaston> References: <1116991600.6395.71.camel@gaston> <20050525095929.GD32472@poupinou.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20050525095929.GD32472@poupinou.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: cpufreq-bounces@lists.linux.org.uk Errors-To: cpufreq-bounces+glkc-cpufreq=gmane.org@lists.linux.org.uk Content-Type: text/plain; charset="us-ascii" To: Bruno Ducrot Cc: cpufreq@lists.linux.org.uk On Wed, 2005-05-25 at 11:59 +0200, Bruno Ducrot wrote: > On Wed, May 25, 2005 at 01:26:40PM +1000, Benjamin Herrenschmidt wrote: > > Hi ! > > > > >From what I've seen, the OnDemand governor works using a timer/workqueue > > pair. > > > > That annoys me a bit as the setup I have on PowerMacs can take several > > ms to transition (due to voltage transition mostly). I don't like the > > idea of hogging keventd that long. > > > > Wouldn't it make sense, especially for setups where transition latency > > is high (by high, I mean significant compared to HZ for example), to > > actually spawn a kthread and do the sampling & switching from there ? > > I'm wondering if in that case a userspace daemon will be more suited.. This is what I do & recommend for powerbook users (so far, powernowd works like a charm), but since OnDemand governor advertises working with latencies as big as 10ms, I was wondering ... Ben.