linux-kernel - Re: [discuss] Re: [PATCH] Allow all Opteron processors to change pstate at same time

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Date:	Wed, 26 Jul 2006 18:54:20 +0200
From:	Andi Kleen <ak@...e.de>
To:	"Langsdorf, Mark" <mark.langsdorf@....com>
Cc:	"Gulam, Nagib" <nagib.gulam@....com>, discuss@...-64.org,
	linux-kernel@...r.kernel.org, cpufreq@...ts.linux.org.uk
Subject: Re: [discuss] Re: [PATCH] Allow all Opteron processors to change pstate at same time


> AMD Opteron(tm) Processor 838 stepping 01
> CPU 3: Syncing TSC to CPU 0.
> CPU 3: synchronized TSC with CPU 0 (last diff -109 cycles, maxerr 1024

Hmm, indeed  - i would have expected higher max errors too.
It should have worked in theory. No explanation currently.

> cycles)
> powernow-k8:    0 : fid 0xe (2200 MHz), vid 0x6
> powernow-k8:    1 : fid 0xc (2000 MHz), vid 0x8
> powernow-k8:    2 : fid 0xa (1800 MHz), vid 0xa
> powernow-k8:    3 : fid 0x2 (1000 MHz), vid 0x12
> 
> Is there a better test we can be using?

I don't know of any. Ok I guess it would be possible to write
something in user space, but it would likely look similar to
the algorithm the kernel uses.

-Andi
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