W dniu 25.03.2014 12:16, Gilles Chanteperdrix pisze:
On 03/25/2014 11:26 AM, Wojciech Domski wrote:
W dniu 24.03.2014 13:19, Gilles Chanteperdrix pisze:
The solution which would be acceptable is not to have busy waits, except
for very short durations. But for instance transferring a byte on I2C
takes around 20us at 400 kHz, a 20us masking section is unacceptable.
rtdm_task_busy_sleep, as the name suggests is a busy wait loop, so, no,
it is not acceptable either.
Use a thread or a timer to reschedule while you wait for the end of the
transfer, instead of busy waiting.
Dear Gilles,
As you mentioned before the driver has few places like this:
while(!FLAG1);
while(!FLAG2);
Would a solution of creating a separate task for this purpose be ok?
task()
{
while(!FLAG1);
while(!FLAG2);
}
I was rather thinking about rtdm_task_sleep() instead.
In the place of those loops a piece of code responsible for creating and
joining task would be put instead:
rtdm_task_init();
rtdm_task_join_nrt();
This will not work for code currently running in interrupt handlers. An
interrupt handler can not call rtdm_task_join_nrt(). You will rather
have to wake up the thread, not reenabling the interrupt at the end of
the handler, and reenable the interrupt in the thread when the job is
done. Or alternatively, fire a timer instead of waking up a thread.
Dear Gilles,
If what I have understood correctly, basically what you mean is changing:
while(!FLAG) ;
into
while(!FLAG)
rtdm_task_sleep();
Xenomai's documentation that rtdm_task_sleep() can be always
rescheduled. In my opinion
this solution is sufficient and meets Xenomai requirements.
Best regards,
Wojciech Domski
Domski.pl
Wojciech.Domski.pl
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