On Fri, Sep 2, 2011 at 10:56 AM, John Stultz johnstul@us.ibm.com wrote:
On Wed, 2011-08-31 at 07:43 +1200, Michael Hope wrote:
I was quite impressed with how steady the process clock was under different CPU loads. It doesn't seem to round up or down to a scheduler tick either which is nice.
Hmm. Very interesting results! Its been a little while since I've looked into the cpu time accounting, but I'd be hesitant to trust that it has finer then HZ granularity everywhere. I know that has been an issue in the past. I'll have to look into it.
I was wondering the same and had a play with it as part of the exercise. Plotted the clock time for differing numbers of loop and didn't see the staircasing effect you'd expect if the time was rounded to the nearest scheduler tick.
I also had a look at the delta between each run and the standard deviation was nice and low - around 50 us.
-- Michael