RE: [Xen-devel] [PATCH] Disable Xen PowerNow! support on Opteron2nd gen and earlier processors

["Ian Pratt" <Ian.Pratt@xxxxxxxxxxxxx>]

> 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.

That shouldn't be an issue either way.

Ian

 
> Shingoshi
> 
> 
> 
> 
> 
> Keir Fraser wrote:
> 
>       On 25/1/08 22:58, "Mark Langsdorf" <mark.langsdorf@xxxxxxx>
> <mailto:mark.langsdorf@xxxxxxx>  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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