Re: Inconsistent timing results of multithreaded program on an SMP machine.

[Con Kolivas <kernel@kolivas.org>]

On Thu, 24 Nov 2005 19:33, Marcel Zalmanovici wrote:
> Hi Con,
>
> I've tried the pthread_join theory.
> pthread_join completes very fast, no evidence on it being the perpetrator
> here.
>
> I've ran your ps -... idea in a different term window every ms while the
> test was running. It created a large file so I won't mail it to you, but
> both me and Muli observed that once the thread ends it quickly disappears
> from the ps list.
>
> I've also ran Muli's idea and added gettimeofday calls.
> Here's the altered code and output:
>
> (See attached file: idle.log)(See attached file: sched_test.c)
>
> As you can see, if a thread already finished pthread_join returns in a
> split second.
>
> Any other ideas are welcome :-)

Profile the actual application?

> P.S. - I agree that Lotus isn't ideal for this kind of conversations, but
> that's what IBM is using.

It was tongue in cheek ;) Well that should still not stop you from replying 
below the original thread.

Cheers,
Con