mmio latency measurements

Harald Welte laforge at gnumonks.org
Thu Jun 30 20:00:36 EST 2005


On Thu, Jun 30, 2005 at 06:56:58PM +1000, Benjamin Herrenschmidt wrote:
> 
> > 1. Is this a valid use of get_cycles()
> > 2. Are there any special caveats ?
> > 3. Please propose an alternative mechanism, in case get_cycles() won't
> >    work
> 
> On ppc64, there is no cycle-counter per-se, but a HW timebase that ticks
> at a fixes frequency (independently of the CPU frequency nowadays).
> That's the value get_cycles() returns. You can see the calibration value
> of the timebase in herz in /proc/cpuinfo.

thanks a lot for your fast reply, I'll adopt the program to acommodate this.

-- 
- Harald Welte <laforge at gnumonks.org>          	        http://gnumonks.org/
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