kernel thread scheduling question

kernel thread scheduling question

[Ben Greear]

I have a kernel thread that I would like to have run at least
every 1-2 miliseconds.

I think I would be happy if there were a way to have the
process yield/schedule() at least once per ms with the
understanding that it would get to wake again 1-2ms later.
Is there a way to do such a thing without hacking up the
scheduler code?

I have tried 2.6.4 with pre-empt, and setting the thread priority
to -18, but I still see cases where the process is starved for 20+
milliseconds every 3-5 seconds or so.  Other than this single
process, there is not a big load on the system.

Any suggestions are welcome.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

Re: kernel thread scheduling question

[Nick Piggin]

Ben Greear wrote:
> I have a kernel thread that I would like to have run at least
> every 1-2 miliseconds.
> 
> I think I would be happy if there were a way to have the
> process yield/schedule() at least once per ms with the
> understanding that it would get to wake again 1-2ms later.
> Is there a way to do such a thing without hacking up the
> scheduler code?
> 
> I have tried 2.6.4 with pre-empt, and setting the thread priority
> to -18, but I still see cases where the process is starved for 20+
> milliseconds every 3-5 seconds or so.  Other than this single
> process, there is not a big load on the system.
> 

Use realtime scheduling. sched_setscheduler (2) is a good
place to start.