Re: [PATCH][DOCUMENTATION BUGFIX] latency in micro-, not nanoseconds

[Dominik Brodowski <linux@brodo.de>]

On Mon, Nov 10, 2003 at 09:16:54PM +0000, Dave Jones wrote:
> On Mon, Nov 10, 2003 at 09:50:29PM +0100, Dominik Brodowski wrote:
> 
>  > > Actually, I'm wondering why we need this at all anyway..
>  > 
>  > To determine the "cost" of frequency and/or voltage transitions when doing
>  > dynamic switching. If the system is unresponsive for too long a period of 
>  > time, dynamic switching doesn't make sense [at least when some sort of
>  > real-time or "responsiveness" is needed]. Also, the time to needed switch 
>  > back to 100% of processing power should be added to the "overhead" idleness
>  > on future load calculations of yet-to-be-written load-predicting cpufreq
>  > governors.
> 
> Ok, I can buy that. But it's not being used at all right now, right ?

It is used in the ondemand governor already. Venkatesh knows of the
documentation bug and of the powernow-k7 bug, though.

BTW, it's not enough for powernow-k7 to divide the BIOS-known latency by 50.
This latency for one VID and one FID transition needs to be multiplied by
the number of p-states minus 1, as that's the actual maximum latency due to
the "one step up/down only" loop, IIRC.

	Dominik