Re: [Xenomai-help] posix functions for real time and non real time

["M. Koehrer" <mathias_koehrer@domain.hid>]

Hi Gilles,

thank you very much for the response.
I tried this out and found one strange thing:
When I run the following simple example (that uses the __real_pthread_ functions)
the executable appears in the /proc/xenomai/stat list.
As I am calling __real_pthread_create() I expected that my program does not appear
in xenomai at all.
Build is done using xeno-config --posix-cflags plus -O2 -Wall. For linking xeno-config --posix-ldflags 
is used.

Another question:
Is there a special header file available that has some defines to map the pthread_xxx
function to __real_pthread_xxx.
By including this header I do not have to modify the C code of that files that should
use the non real-time functions.

Thanks for any response on that.

Regards

Mathias

-------------- BEGIN OF CODE ---------------
#include <stdio.h>
#include <sys/mman.h>
#include <pthread.h>

#define USE_REAL
pthread_t thread;

void *mytaska(void *cookie)
{
    int i;
    for (i=0; i < 5; i++)
    {
        struct timespec rqtp;
        printf("Task A\n");
        rqtp.tv_sec = 1;
        rqtp.tv_nsec = 0;
#ifdef USE_REAL
        __real_nanosleep(&rqtp, 0);
#else
        nanosleep(&rqtp, 0);
#endif
    }
    return 0;
}

int main(void)
{
    int i;
    mlockall(MCL_CURRENT|MCL_FUTURE);
    printf("pid: %i\n", getpid());
#ifdef USE_REAL
    __real_pthread_create(&thread, NULL, mytaska, NULL);
#else
    pthread_create(&thread, NULL, mytaska, NULL);
#endif
    for (i=0; i<3; i++)
    {
        struct timespec rqtp;
        printf("Main\n");
        rqtp.tv_sec = 1;
        rqtp.tv_nsec = 0;
#ifdef USE_REAL
        __real_nanosleep(&rqtp, 0);
#else
        __nanosleep(&rqtp, 0);
#endif
    }
    pthread_join(thread, NULL);
    printf("Main: A joined\n");
    return 0;
}
------------- END OF CODE ----------


> On Jan 8, 2008 8:17 AM, M. Koehrer <mathias_koehrer@domain.hid> wrote:
> > Hi everybody,
> >
> > I have a fairly huge application that consists of several real time
> threads and several non real time (posix) threads.
> > For the non real time threads I use the pthread_create function and e.g.
> the pthread_mutex_lock/unlock functions to
> > synchronize them.
> > Is it possible to use the Xenomai Posix skin for real time threads as
> well?
> > When linking against pthread_rt and pthread I have two "variants" of e.g.
> pthread_create. One to be used for real
> > time threads and one for the non real time threads. How are they
> distinguished?
> > How can I define to create a real time task using pthread_create and how
> can I define to create a non real time task
> > using pthread_create.
> 
> In fact, linking agains pthread_rt is not enough to use Xenomai posix
> skin real-time services, in order to get the real-time pthread_create,
> you have to add to the link flags of your application
> -Wl,--wrap,pthread_create. Note that you do not have to pass the
> --wrap yourself, xeno-config --posix-ldflags will pass all the --wrap
> flags.
> 
> Once you pass the -Wl,--wrap,pthread_create to gcc, all calls to
> pthread_create in your code are replaced with calls to
> __wrap_pthread_create, and all calls to __real_pthread_create are
> replaced with calss to the original, non wrapped, pthread_create.
> 
> So, when an application is compiled for Xenomai posix skin, the
> pthread_* services are the real-time services, and the
> __real_pthread_* services are non real-time services.
> 


-- 
Mathias Koehrer
mathias_koehrer@domain.hid


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