Re: fair clock use in CFS

[Srivatsa Vaddagiri <vatsa@in.ibm.com>]

On Mon, May 14, 2007 at 10:31:13AM -0400, Daniel Hazelton wrote:
> Hrm... Okay, so you're saying that "fair_clock" runs slower the more process 
> there are running to keep the above run-up in "Time Spent on CPU" I noticed 
> based solely on your initial example? If that is the case, then I can see the 
> fairness - its just not visible from a really quick look at the code and the 
> simplified description you gave earlier.

>From the code:

update_curr() 

        delta_fair = delta_exec * NICE_0_LOAD;
        do_div(delta_fair, rq->raw_weighted_load);

	..

	rq->fair_clock += delta_fair;

Although wall clock would have advanced by delta_exec, fair clock
advances only by delta_fair.

More the load on the CPU (rq->raw_weighted_load), slower is this advance
compared to wall clock.



-- 
Regards,
vatsa