Re: [PATCH] Disable Xen PowerNow! support on Opteron 2nd gen and earlier processors

[Xavian-Anderson Macpherson <Shingoshi@comcast.net>]

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Are we in fact talking about the new Barcelona chips? If so, their 
frequency settings are independent per core. Unless I have misunderstood 
the question.

Shingoshi



Keir Fraser wrote:
> On 25/1/08 22:58, "Mark Langsdorf" <mark.langsdorf@amd.com> wrote:
>
>   
>> I tried this suggestion and also implemented the trace function in
>> cpu_frequency_change() and local_time_calibration() you suggested in
>> a previous message.
>>
>> It made no discernable difference in my tests.  I did high to low
>> and low to high changes roughly every five minutes, and always got
>> an excessive difference inside of Xen and usually got error messages
>> in Linux.
>>     
>
> It's a bit confusing as to what is going on since there are 4 CPUs in the
> system. Are arbitrary or all CPUs changing frequency, or just one of them?
> Is the single-step PSTATE_CTRL MSR being used, or the multi-step FID_VID
> method where voltage adjustments are under software control? What is the
> system's CPU topology, and do any of the cores have their frequency controls
> tied together?
>
> It'd be useful to have each tracing line stamped with the CPU that it comes
> from. As it is the tracing looks very suspect because the systimes on
> adjacent lines are much less than one second, and calibration is supposed to
> happen no more than once per second.
>
>  -- Keir
>
>
>
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>   

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