Difference between rt_task, pthread and xnthread in Xenomai 3

Difference between rt_task, pthread and xnthread in Xenomai 3

[Jae Hyun Park]

Hi, 

I have been used rt_task_create from Xenomai 2. 

In the Xenomai 3 cobalt example, it seemed to use only pthread_create.

I'm not familiar to task, process and thread... 

I have several question belong to thread_create and rt_task_create.

1. does rt_task_create create a process(task) instead of creating a single thread?

2. Is creating thread is better than using rt_task_create in Xenomai 3? I'm wondering now we are not using rt_task_create.
   
3. Is there difference between xnthread and pthread?

Thanks. 

Re: Difference between rt_task, pthread and xnthread in Xenomai 3

[Richard Weinberger]

On Thu, Apr 21, 2022 at 8:21 AM Jae Hyun Park via Xenomai
<xenomai@xenomai.org> wrote:
> I have been used rt_task_create from Xenomai 2.
>
> In the Xenomai 3 cobalt example, it seemed to use only pthread_create.

It depends on the skin. rt_task_create is part of the native/alchemy skin.
While pthread_create is part of the posix skin.

Xenomai offers multiple interfaces to use realtime.

> I'm not familiar to task, process and thread...
>
> I have several question belong to thread_create and rt_task_create.
>
> 1. does rt_task_create create a process(task) instead of creating a single thread?

No. See above.

> 2. Is creating thread is better than using rt_task_create in Xenomai 3? I'm wondering now we are not using rt_task_create.

Depends. Many people prefer the posix skin because it feels familiar.

> 3. Is there difference between xnthread and pthread?

xnthread is Xenomai's internal kernel structure to represent a realtime thread.

-- 
Thanks,
//richard

Re: Difference between rt_task, pthread and xnthread in Xenomai 3

[Jae Hyun Park]

>> I have been used rt_task_create from Xenomai 2.
>>
>> In the Xenomai 3 cobalt example, it seemed to use only pthread_create.

>It depends on the skin. rt_task_create is part of the native/alchemy skin.
>While pthread_create is part of the posix skin.

>Xenomai offers multiple interfaces to use realtime.

>> I'm not familiar to task, process and thread...
>>
>> I have several question belong to thread_create and rt_task_create.
>>
> 1. does rt_task_create create a process(task) instead of creating a single thread?

>No. See above.

>> 2. Is creating thread is better than using rt_task_create in Xenomai 3? I'm wondering now we are not using rt_task_create.

>Depends. Many people prefer the posix skin because it feels familiar.

>> 3. Is there difference between xnthread and pthread?

>xnthread is Xenomai's internal kernel structure to represent a realtime thread.

>-- 
>>Thanks,
>//richard

--

Thanks for responding. 

Then can I understand that tasks made with rt_task_create work similarly to multi-threading?

And I wonder if there is any difference in real-time guarantee performance between pthread 

of posix skin and xnthread of realtime thread of xenomai.

Re: Difference between rt_task, pthread and xnthread in Xenomai 3

[Richard Weinberger]

On Fri, Apr 22, 2022 at 5:02 AM Jae Hyun Park <parkjahun42@naver.com> wrote:
> Then can I understand that tasks made with rt_task_create work similarly to multi-threading?
>
> And I wonder if there is any difference in real-time guarantee performance between pthread
>
> of posix skin and xnthread of realtime thread of xenomai.

Skins are implemented in user space, so there shouldn't be a difference.
>From the kernel point of view they are all threads.

-- 
Thanks,
//richard