Re: Call to the scheduler...

[Rob Landley]

On Tuesday 24 July 2001 13:54, Richard B. Johnson wrote:

> Try sched_yield(). Accounting may still be messed up so the process
> may be 'charged' for CPU time that it gave up. Also, usleep(n) works
> very well with accounting working.
>
> This works, does not seem to load the system, but `top` shows
> 99+ CPU time usage:
>
> main()
> {
>     for(;;) sched_yield();
>
> }

This may not be an accounting problem.  If the system has nothing else to do, 
it'll just re-schedule your yielding thread.

How much of that 99% cpu usage is user and how much of it is system?  
Basically what the above does is beat the scheduler to death...

> This works and `top` shows nothing being used:
>
> main()
> {
>
>     for(;;) usleep(1);
>
> }

And here you DO block for a bit without getting called back immediately.

I don't think that's an accounting thing, I think it's different behavior.  
(Could be wrong, as always...)

>
> Cheers,
> Dick Johnson

Rob