On Tue, May 22, 2007 at 10:59:22AM -0400, Michael Dickens wrote:
> On May 22, 2007, at 12:28 AM, Eric Blossom wrote:
> >The priority is set to the midpoint of the FIFO range, not maximized.
>
> My bad on the "maximized" ... but ... ummm ... no, not the midpoint
> either the way it's written, if I understand the function calls
> correctly. Here's the line:
>
> int pri = (sched_get_priority_max (policy) -
> sched_get_priority_min (policy)) / 2;
>
> The midpoint would be (... + ...) / 2. ;)
Thanks. Fixed in the trunk.
> >I don't think we want to be creating new threads just to try
> >to set real time scheduling.
>
> These changes are made to the current running thread, not to a new
> thread, just like the code in "gr_realtime.cc". IMHO GNU Radio
> already has enough threads, especially on OSX's implementation
> because of Apple's weirdness of requiring separate threads for
> callbacks on Audio and USB.
>
> >I strongly suspect that if a pthread
> >implementation supports pthread_attr_setschedpolicy with SCHED_RR or
> >SCHED_FIFO, then they will also implement sched_setscheduler with
> >SCHED_RR or SCHED_FIFO.
>
> On OSX 10.4.9 (and, I would presume any 10.4.X):
> sched_get_priority_max(), sched_get_priority_min (), SCHED_FIFO, and
> "struct sched_param" [and "struct sched_param".sched_priority] are
> defined in standard header files in /usr/include and seem to work as
> required for modifying the scheduling priority and policy.
> Strangely, the only part that's missing from headers is
> sched_setscheduler() ... which gets divided and renamed to
> pthread_attr_setschedpolicy() and pthread_attr_setschedparam().
pthread_attr_setschedpolicy is not the same thing as
sched_setscheduler. It's for setting up the attribute that is passed
pthread_create. The friendly manual says:
NAME
pthread_attr_getschedpolicy, pthread_attr_setschedpolicy - get and set
the schedpolicy attribute (REALTIME THREADS)
...
APPLICATION USAGE
After these attributes have been set, a thread can be created with the
specified attributes using pthread_create(). Using these routines does
not affect the current running thread.
Eric
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