On 2014-07-04 17:12, Daniel Cederman wrote:
> This limits the API to the default cpu_set_t. Other routines like
> pthread_setaffinity_np() don't have this limitation.
I looked at pthread_setaffinity_np() and got a bit confused. I see that it
takes both a pointer to a cpu_set_t and the size of the cpu set. It forwards it
to _Scheduler_Set_affinity which requires __RTEMS_HAVE_SYS_CPUSET_H__ to be
defined. If this is defined then _CPU_set_Handler_initialization checks that
the number of cpus is less than CPU_SETSIZE. In newlib this is defined to 32
and is used to size the cpu_set_t struct. So why is the size needed for
pthread_setaffinity_np if the number of cpus cannot exceed a hardcoded
constant? I recall that there was a discussion on the list about cpu sets, but
I'm not finding anything searching.
There are CPU set functions that support an arbitrary number of processors,
just look at the Linux manpage or <sys/cpuset.h>. This is normally only useful
on NUMA systems, but who knows what will be used for real-time systems in the
future.
--
Sebastian Huber, embedded brains GmbH
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