Re: How is user space notified of CPU speed changes?

[Lee Revell]

On Fri, 2004-10-22 at 07:23, Alan Cox wrote:
> On Gwe, 2004-10-22 at 00:01, Lee Revell wrote:
> > This issue came up on the JACK (http://jackit.sf.net) mailing list. 
> > Google was not helpful so I ask here.
> > 
> > JACK needs to know the CPU speed, in order to calculate the DSP load
> > among other things.  It used to be a valid assumption that you could
> > calculate it on startup and it would not change.
> 
> No it did not. It has never been a safe assumption. Even my old PC110
> does APM non-linux assisted shifts between 8 16 and 33Mhz. In addition
> there are boxes with dual CPU's and different multipliers - dual 
> 300/450's were not uncommon.
> 
> And thats before we even mention such things at hyped-threading.

Seems like you are implying that any userspace app that needs to know
the CPU speed is broken.  Is this correct?

Lee

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