[Xenomai-help] Waiting w/o burning CPU

[Xenomai-help] Waiting w/o burning CPU

[Jozsef Lazar]

Hi,

Could anyone tell me which Xenomai function should I use to wait (even 
up to 100msecs) without burning CPU. I tried using nanosleep() but it 
was always returning with 1 (one) and analyzing my output pins with an 
oscilloscope I couldn't see any time delays. Now I use rt_timer_spin() 
but I'm not sure whether I'm doing any wrong to my rt threads (or anyone 
else in the kernel). My environment: a kernel driver with lots of rt 
threads controlling stepper motors. The function where I want to wait is 
a work_struct task (called by a schedule_work). Thanks.

-- joseph

Re: [Xenomai-help] Waiting w/o burning CPU

[Gilles Chanteperdrix]

Jozsef Lazar wrote:
> Hi,
> 
> Could anyone tell me which Xenomai function should I use to wait (even 
> up to 100msecs) without burning CPU. I tried using nanosleep() but it 
> was always returning with 1 (one) and analyzing my output pins with an 
> oscilloscope I couldn't see any time delays. Now I use rt_timer_spin() 
> but I'm not sure whether I'm doing any wrong to my rt threads (or anyone 
> else in the kernel). My environment: a kernel driver with lots of rt 
> threads controlling stepper motors. The function where I want to wait is 
> a work_struct task (called by a schedule_work). Thanks.

A work_struct task is a Linux task, not a xenomai thread. Xenomai
functions work for Xenomai thread. The behaviour of nanosleep is
documented here:

http://www.xenomai.org/documentation/xenomai-2.4/html/api/group__posix__time.html#ga9ce6a1ed91a601dee133c8b6cf8b721a

1 is EPERM.

-- 
                                          Gilles

Re: [Xenomai-help] Waiting w/o burning CPU

[Gilles Chanteperdrix]

Jozsef Lazar wrote:
> Gilles Chanteperdrix írta:
>> Jozsef Lazar wrote:
>>   
>>> Hi,
>>>
>>> Could anyone tell me which Xenomai function should I use to wait (even 
>>> up to 100msecs) without burning CPU. I tried using nanosleep() but it 
>>> was always returning with 1 (one) and analyzing my output pins with an 
>>> oscilloscope I couldn't see any time delays. Now I use rt_timer_spin() 
>>> but I'm not sure whether I'm doing any wrong to my rt threads (or anyone 
>>> else in the kernel). My environment: a kernel driver with lots of rt 
>>> threads controlling stepper motors. The function where I want to wait is 
>>> a work_struct task (called by a schedule_work). Thanks.
>>>     
>>
>> A work_struct task is a Linux task, not a xenomai thread. Xenomai
>> functions work for Xenomai thread. The behaviour of nanosleep is
>> documented here:
>>
>> http://www.xenomai.org/documentation/xenomai-2.4/html/api/group__posix__time.html#ga9ce6a1ed91a601dee133c8b6cf8b721a
>>
>> 1 is EPERM.
>>
>>   
> Thank you for your answer. I thought that I have such a problem. Any
> suggestions which function should I use?

Linux provides several functions for suspending threads, such as msleep,
schedule_timeout_interruptible, wait_event_interruptible, whatever you
want. Anyway this question is related to Linux, not to Xenomai, so you
will find better answers in other places than on Xenomai mailing-lists,
I am not even sure you can suspend a work queue.

Please do not drop the CC to mailing list when replying.

Regards.

-- 
                                          Gilles