[tesla-dev] Turbo Mode Support for Solaris

[Vinay Devadas]

thanks Jim. Will contact you if I have further questions,

-Vinay

----- Original Message -----
From: Jim Britton <Jim.Britton at Sun.COM>
Date: Friday, June 20, 2008 11:28 am
Subject: Re: Turbo Mode Support for Solaris
To: Vinay Devadas <Vinay.Devadas at Sun.COM>
Cc: tesla-dev at opensolaris.org


> Hi Vinay,
> 
> To be honest, I have not looked that closely at PowerTop or how it 
> works 
> today.  I am assuming it is similar to prstat or top.  But I hate to 
> speculate too much, so let me give you an example of what I would like 
> 
> to be able to know.
> 
> Frequently industry standard benchmarks require a certain degree of 
> reproducibility, say within 5% of our submitted result.  Turbo Mode 
> opens up the potential for a much less reproducible run because our 
> core 
> clocks are not 100% deterministically controlled.  What I would like 
> PowerTop to enable is the ability tell how much time was spent in 
> Turbo 
> Mode, during the course of a benchmark run.  I assume this would also 
> be 
> interesting to customers looking at what their own systems are up to 
> as 
> well.
> 
> Ideally, I would see a big benefit in being able to log frequencies 
> used 
> over the course of a run, similar to mpstat's output about 
> utilization.  
> Then we can chart the logs over time and see how things are 
> fluctuating 
> during our benchmark runs.
> 
> Feel free to let me know if you have any other questions.
> 
> Thanks,
> 
> Jim
> 
> Vinay Devadas wrote:
> > Hi Jim,
> >
> > I just had a question about the bug you reported about Turbo Mode 
> not being supported on PowerTop. Wanted to clarify what sort of 
> statistic did you have in mind when you reported the bug. With the 
> observability provided by intel, I believe we can only say we were in 
> turbo mode for some time during the last sampling interval. We feel 
> the average CPU frequency overall the last sampling interval may be a 
> more useful statistic.  Please let us know on what you think.
> >
> > Thanks,
> > Vinay
> >   
> 
> -- 
>   Jim Britton  -  Performance Lead  -  jim.britton at sun.com
>      X64 Product Development  -  Sun Microsystems, Inc.
>         400 Atrium Drive, USMT01, Somerset, NJ 08873
>               732.302.3864  -  F:732.469.4098 
>