Re: [RFC PATCH v1 0/3] Scaled statistics using APERF/MPERF in x86

[Pavel Machek]

Hi!

> > entitlement for the process as per the current CPU frequency.  This
> > technique is used in powerpc architecture with the help of hardware
> > registers that accurately capture the entitlement.
> > 
> 
> there are some issues with this unfortunately, and these make it
> a very complex thing to do. 
> Just to mention a few:
> 1) What if the BIOS no longer allows us to go to the max frequency for
> a period (for example as a result of overheating); with the approach
> above, the admin would THINK he can go faster, but he cannot in reality,
> so there's misleading information (the system looks half busy, while in

Plus time one-second-computation-job returning anything else is just
wrong. Even when it only happens when overheated... or only on battery
power.

If you want scaled utime, you need new interface.

							Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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