Paolo Gai wrote:
> Gilles Chanteperdrix wrote:
> >Working around this issue means using calls to unlocked versions of libc
> >functions protected with Xenomai POSIX mutexes, such as, for example,
> >myputs and myputchar (sufficient for Paolo example) defined as :
> >[...]
> >
> >
> Ok! I tried it, and I also tried another slightly modified version of
> the demo, that simply replaces putchars with an unprotected array of
> chars (let's suppose there are no race conditions) that is printed out
> to stdout at the end of the game.
There is no race condition in the SCHED_FIFO case or ahem, there should
be none. Please also note that the "volatile" qualifier seem misplaced
in your declaration of buf_current, it may matter since the compiler
will probably inline calls to myputchar in the "medium" function, and
buf_current will end up in a register. But this would have no effect
only in the SCHED_FIFO case.
> the results are the following, where the first part is RR and the second
> is FIFO (it's quite strange for me that FIFO has more contect changes
> than RR (?))
Please also note that any thread created with the SCHED_RR attribute
will be a plain Linux thread, and due to a bug in glibc, the thread will
use the default policy. The results are strange indeed for SCHED_FIFO,
it may be a bug, this needs a closer look... Maybe threads are not
Xenomai threads using SCHED_FIFO policy at all ?
--
Gilles Chanteperdrix.
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