Re: [Xenomai] cpu usage

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

On 07/27/2012 03:58 PM, Frederik Bayart wrote:

> The use case is : we are using an i7 processor. We noticed that
> internally, the processor is shifting frequency to minimize idle time.
> (This is not done by linux, we used cpufreq to avoid that but there is
> still some software on the processor that is shifting frequency). This
> has as consequence that the required rate of our realtime process,
> which is a periodic task, becomes to fast for the processor.
> To avoid downscaling of the cpu frequency, we had the  idea to run
> additionally a busywait loop at priority 0 so that the processor is
> always running at 100%, there is no idle time and the frequency will
> not scale down.
> 
> We want only 1 core running at 100% for temperature reasons.


Then simply put the busy loop in a task not running with real-time
priority. A plain Linux task. You should also use the SCHED_IDLE policy
in order to avoid it to delay other non real-time task.

-- 
                                                                Gilles.