Application based on Pthreads is blocked under RTEMS

[Joel Sherrill]

On Jul 4, 2014 8:33 AM, smc smc <smc101979 at gmail.com> wrote:
>
> Hi, thanks all for your suggestions.
>
> @Sebastian: the bsp is MPPA.
> @Gedare: I cannot send the full code for debugging, because part of it uses an proprietary API :/ About your comment, I commit a mistake transcribing the code, it is not an assignment operator, it must be '=='.

You should be able to produce a generic version that bus smaller and reproduces the problem.

You did not answer if you have default attributes on the pthreads and other objects. They are undefined by POSIX and differ between RTEMS and Linux.

Also a thread spinning in a loop at the highest priority in RTEMS will do that forever. My impression is that is what your init thread is doing.

> Anyway, I am trying to use condition variables, despite of loosing some of performance.
>
> Regards.
>
>
>
> 2014-07-03 2:37 GMT+01:00 Gedare Bloom <gedare at rtems.org>:
>>
>>  I'll make one note below, but you should submit the entire
>> self-contained example that shows the incorrect behavior if you want
>> debugging help.
>>
>> On Wed, Jul 2, 2014 at 6:23 AM, smc smc <smc101979 at gmail.com> wrote:
>> > Hi, I am new in RTEMS. I can't understand why the following threaded
>> > application is not running on RTEMS as expected. Basically, it creates two
>> > pthreads. One fills a buffer and the other one get an slice and submit it to
>> > a cluster for processing (typical producer-consumer problem), something
>> > like:
>> >
>> > void thread1()
>> > {
>> >   while(1)
>> >   {
>> >     for (i=0; i < size;i++)
>> >     {
>> >       if (buffer[i].st == -1)
>> >       {
>> >         pthread_mutex_lock(&mutex);
>> >           genData(buffer[i]);
>> >           buffer[i].st=0;            // ready to be consumed
>> >         pthread_mutex_unlock(&mutex);
>> >       }
>> >     }
>> >   }
>> > }
>> >
>> > void thread2()
>> > {
>> >   while(1)
>> >   {
>> >     // n stores the slice start
>> >     ready = false;
>> >     while (!ready)                 // it gets a free slice
>> >     {
>> >       ready = true;
>> >       for(i=n;i<n+slice;i++)
>> >         if (buffer[i].st = -1)
>> If you have this statement with an assignment operator, the
>> while(!ready) loop should never terminate if slice > 0.
>>
>> >           ready = false;
>> >      }
>> >     // process the slice on cluster
>> >    pthread_mutex_lock(&mutex);
>> >       for (i=n;i<n+slice;i++)
>> >         buffer[i].st = -1;       // now new data can be inserted on it
>> >    pthread_mutex_unlock(&mutex);
>> >   }
>> > }
>> >
>> > It runs fine on a Linux/GNU system, but not in RTEMS. Under some
>> > circumstances the program is blocked. It is like if thread2 was running
>> > forever on the second while, and thread1 didn't fill the buffer. Do you have
>> > any idea of what is happening? I would expect that each thread would run on
>> > parallel on each core.
>> >
>> > Thanks.
>> >
>> > _______________________________________________
>> > users mailing list
>> > users at rtems.org
>> > http://lists.rtems.org/mailman/listinfo/users
>
>
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