[Xenomai] Switch to secondary mode due to pop/push into TBB queue

[Xenomai] Switch to secondary mode due to pop/push into TBB queue

[Mnatsakanyan, M.]

Hello,

I am trying to build a real-time application, but still do not understand all Xenomai concepts clearly, so I'm having difficulty to explain why my rt task switches to secondary mode.

My tasks communicate using TBB concurrent_bounded_queue. Whenever the tasks push or pop into the queue they switch to secondary mode.

I am aware of RT_QUEUE provided by Xenomai, but I would like to avoid making this change.
My question is: is it possible to prevent mode switch while still using TBB queue? And how this mode switch can be explained? I read that system calls cause mode switch, but here I cannot recognize a system call.

Thank you,
Mari

Re: [Xenomai] Switch to secondary mode due to pop/push into TBB queue

[Gilles Chanteperdrix]

On 03/25/2014 05:03 PM, Mnatsakanyan, M. wrote:
> Hello,
>
> I am trying to build a real-time application, but still do not understand all Xenomai concepts clearly,

So, I suggest you read the documentation at http://www.xenomai.org

-- 
					    Gilles.

Re: [Xenomai] Switch to secondary mode due to pop/push into TBB queue

[Mnatsakanyan, M.]

Sorry if my question is not worthy to post here.
I read a lot from xenomai documentation and discussions, but still cannot answer this question.

________________________________________
From: Gilles Chanteperdrix [gilles.chanteperdrix@xenomai.org]
Sent: Tuesday, March 25, 2014 5:13 PM
To: Mnatsakanyan, M.
Cc: xenomai@xenomai.org
Subject: Re: [Xenomai] Switch to secondary mode due to pop/push into TBB queue

On 03/25/2014 05:03 PM, Mnatsakanyan, M. wrote:
> Hello,
>
> I am trying to build a real-time application, but still do not understand all Xenomai concepts clearly,

So, I suggest you read the documentation at http://www.xenomai.org

--
                                            Gilles.

Re: [Xenomai] Switch to secondary mode due to pop/push into TBB queue

[Philippe Gerum]

On 03/25/2014 05:35 PM, Mnatsakanyan, M. wrote:
> Sorry if my question is not worthy to post here.
> I read a lot from xenomai documentation and discussions, but still cannot answer this question.

The threading building blocks consists of a huge amount of code not even 
remotely designed for running over a dual kernel system, so they issue 
regular linux system calls under the hood, either directly or indirectly 
by calling other library services. Not to speak of the C++ runtime which 
introduces its own set of issues.

In short, TBB won't care about a very basic Xenomai 2.x requirement: 
services in real-time mode (i.e. primary) should be obtained from 
Xenomai APIs, excluding regular linux system calls. One of these APIs is 
a subset of the POSIX specification aimed at real-time programming 
though, but this is likely not enough to cover every service the TBB 
invokes.

Diving into the TBB implementation would be required to figure out what 
happens there, and whether using a construct in real-time mode over a 
dual kernel is ever possible.

>
> ________________________________________
> From: Gilles Chanteperdrix [gilles.chanteperdrix@xenomai.org]
> Sent: Tuesday, March 25, 2014 5:13 PM
> To: Mnatsakanyan, M.
> Cc: xenomai@xenomai.org
> Subject: Re: [Xenomai] Switch to secondary mode due to pop/push into TBB queue
>
> On 03/25/2014 05:03 PM, Mnatsakanyan, M. wrote:
>> Hello,
>>
>> I am trying to build a real-time application, but still do not understand all Xenomai concepts clearly,
>
> So, I suggest you read the documentation at http://www.xenomai.org
>
> --
>                                              Gilles.
>
> _______________________________________________
> Xenomai mailing list
> Xenomai@xenomai.org
> http://www.xenomai.org/mailman/listinfo/xenomai
>


-- 
Philippe.