linux-kernel - Re: [PATCH RESEND] tools: add power/x86/x86_energy_perf_policy to program MSR_IA32_ENERGY_PERF

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Date:	Mon, 22 Nov 2010 23:48:26 -0500 (EST)
From:	Len Brown <lenb@...nel.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Greg Kroah-Hartman <gregkh@...e.de>,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH RESEND] tools: add power/x86/x86_energy_perf_policy to
 program MSR_IA32_ENERGY_PERF_BIAS

On Mon, 22 Nov 2010, Andi Kleen wrote:

> On Mon, Nov 22, 2010 at 03:13:24PM -0500, Len Brown wrote:
> > Per the comments from Andrew and others, the concept of a
> > "full tools build" doesn't actually exit (yet).
> > 
> > So I guess the only assurance that somebody not on x86 would run
> > make in this directory this utility lives in tools/power/x86/
> > 
> > Note that there are other utilities under tools
> > which have no Makefile at all...
> 
> I suspect this will need to be fixed at some point.
> 
> e.g. kernel rpms probably don't want to hard code all of this
> but just call some standard make file target. And the kernel
> eventually needs a make install_user or similar.

I agree, but I don't volunteer to set up such
a build system as part of this particular patch.
As I mentioned, supplying any Makefile is
a step better than some of the peers...

> > I'm not inclined to bother, as the use-case for this utility
> > is to be invoked by another program, and the options available
> 
> What other program?
> 
> I could well imagine administrators sticking this 
> into their boot.locals to set the policy they want.

right, and that would be a program.
It is unlikely that users are going to be typing this
command, except into an admin script.

> > In the highly unlikely scenario that somebody uses
> > the -r option to excerise the read-only code,
> > and simultaneously invokes and completes a cpu hot remove
> 
> FWIW there are setups where core offlining can happen
> automatically in response to an error.

Understood.  I think it is fine if this utility
simply exits if that error occurs while it is running.

(turbostat, OTOH, may be long running, and it treats
 vanishing processors as a recoverable error)

thanks,
-Len Brown, Intel Open Source Technology Center


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