From: Dave Jones <davej@redhat.com>
To: Ryan Underwood <nemesis@icequake.net>
Cc: Cpufreq@lists.linux.org.uk
Subject: Re: writing a cpufreq driver
Date: Thu, 21 Sep 2006 16:44:02 -0400 [thread overview]
Message-ID: <20060921204402.GA26683@redhat.com> (raw)
In-Reply-To: <20060921200851.GF2364@dbz.icequake.net>
On Thu, Sep 21, 2006 at 03:08:51PM -0500, Ryan Underwood wrote:
>
> On Thu, Sep 21, 2006 at 03:31:41PM -0400, Dave Jones wrote:
> > >
> > > 1. The first time cpufreq changes speed, I get the whole "Losing some
> > > ticks... checking if CPU frequency changed." then eventually "Losing too
> > > many ticks!" and timer switches to PIT. This does not happen when I use
> > > the /dev/toshiba driver to change speeds from userspace. Not sure what
> > > is going on here... SMI handler latency is between 6 and 7 ms.
> >
> > Is loops_per_jiffy being correctly scaled on a speed transition?
>
> No, because only the firmware knows what the real CPU speeds are. How
> would I deal with this?
Actually, if your driver is correctly using cpufreq_notify_transition()
it should be doing this automagically for you. If you turn on debugging with
cpufreq.debug=7 , you should see lines of the form.
scaling loops_per_jiffy to %lu for frequency %u kHz\n
Dave
next prev parent reply other threads:[~2006-09-21 20:44 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-21 18:48 writing a cpufreq driver Ryan Underwood
2006-09-21 19:31 ` Dave Jones
2006-09-21 19:38 ` Langsdorf, Mark
2006-09-21 19:47 ` Dave Jones
2006-09-22 15:44 ` Bruno Ducrot
2006-09-22 15:49 ` Dave Jones
2006-09-21 20:08 ` Ryan Underwood
2006-09-21 20:44 ` Dave Jones [this message]
2006-09-21 21:03 ` Ryan Underwood
2006-09-21 21:13 ` Dave Jones
2006-09-22 14:13 ` Ryan Underwood
2006-09-22 14:39 ` Ryan Underwood
2006-09-22 15:48 ` Bruno Ducrot
2006-09-22 16:01 ` Ryan Underwood
2006-09-22 15:51 ` Dave Jones
2006-09-22 15:39 ` Bruno Ducrot
2006-09-22 16:00 ` Ryan Underwood
2006-09-22 16:05 ` Bruno Ducrot
2006-09-22 16:11 ` Ryan Underwood
2006-09-23 15:07 ` Bruno Ducrot
2006-09-23 15:21 ` Ryan Underwood
2006-09-23 15:44 ` Bruno Ducrot
2006-09-23 16:03 ` Ryan Underwood
2006-09-23 16:13 ` Bruno Ducrot
2006-09-25 15:39 ` Ryan Underwood
2006-10-02 2:19 ` Dominik Brodowski
2006-09-25 16:44 ` Ryan Underwood
-- strict thread matches above, loose matches on Subject: below --
2006-09-22 16:31 Erik Slagter
2006-09-23 15:31 ` Bruno Ducrot
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