Subject: Re: Still seeing problems with "time cmd"
To: None <>
From: Jason Thorpe <>
List: tech-kern
Date: 05/30/2003 12:11:31
On Friday, May 30, 2003, at 01:04  AM, Richard Earnshaw wrote:

> No, it's an ARM-based cats board.
>> Is the system running the cycle-counter based microtime?
> What's that?  How do I tell?

You're not :-)

SA-110 doesn't have a cycle counter.

A "cycle-counter based microtime" uses a cycle counter in a processor's 
performance monitoring unit to interpolate the number of microseconds 
that have gone by since the last clock tick, thus making microtime more 
accurate.  The cycle counter is used because it provides a very high 

If you can read the timer's "count-down" register, you can also use 
that in microtime as well.  The XScale ports I've worked on do this, 
and I think the footbridge timer code used by the CATS port does this, 
as well, but there could always be a bug lurking.

         -- Jason R. Thorpe <>