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From: Dominik Brodowski <linux@dominikbrodowski.net>
To: Dave Jones <davej@redhat.com>,
	Nish Aravamudan <nish.aravamudan@gmail.com>,
	William Heimbigner <icxcnika@mar.tar.cc>,
	linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC] [PATCH] cpufreq: allow full selection of default governors
Date: Thu, 26 Apr 2007 21:54:10 -0400	[thread overview]
Message-ID: <20070427015410.GA9650@isilmar.linta.de> (raw)
In-Reply-To: <20070425000327.GG22267@redhat.com>

On Tue, Apr 24, 2007 at 08:03:27PM -0400, Dave Jones wrote:
> On Tue, Apr 24, 2007 at 03:05:36PM -0700, Nish Aravamudan wrote:
>  > On 4/24/07, Dave Jones <davej@redhat.com> wrote:
>  > > On Tue, Apr 24, 2007 at 09:03:23PM +0000, William Heimbigner wrote:
>  > >  > The following patches should allow selection of conservative, powersave, and
>  > >  > ondemand in the kernel configuration.
>  > >
>  > > This has been rejected several times already.
>  > > Ondemand and conservative isn't a viable governor for all cpufreq
>  > > implementations (ie, ones with high switching latencies).
>  > 
>  > This piques my curiosity -- some governors don't work with some
>  > cpufreq implementations. Are those implementations in the kernel or in
>  > userspace? If in the kernel, then perhaps there should be some
>  > dependency expressed there in Kconfig between cpufreq implementation
>  > and the available governors
> 
> it can't be solved that easily. powernow-k8 for example is fine to
> use with ondemand on newer systems, where the latency is low.
> On older models however, it isn't.
> 
>  > > Also, see the
>  > > comment in the Kconfig a few lines above where you are adding this.
>  > 
>  > Are these governors unfixable? If
> 
> tbh, I've forgotten the original issues that caused the comment
> to be placed there. Dominik ?

Not unfixable, but: cpufreq is currently[*] built around the assumption that
at least one governor is correctly initialized or can be brought to work
when a CPU is registered with the cpufreq core.

	Dominik


[*] That is, the last time I looked at it ;)

  reply	other threads:[~2007-04-27  1:54 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-24 21:03 William Heimbigner
2007-04-24 21:12 ` Dave Jones
2007-04-24 21:25   ` Chuck Ebbert
2007-04-24 22:05   ` Nish Aravamudan
2007-04-25  0:03     ` Dave Jones
2007-04-27  1:54       ` Dominik Brodowski [this message]
2007-04-27  6:09         ` Dave Jones
2007-04-27 12:24           ` Dominik Brodowski
2007-04-27 13:40             ` William Heimbigner
2007-04-27 17:06             ` Gautham Shenoy
2007-04-27 18:17               ` William Heimbigner
2007-04-24 22:35   ` William Heimbigner
2007-04-24 21:13 ` Robert P. J. Day

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