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Re: Unique priorities
Jonathan Larmour <jlarmour@redhat.com> writes:
> Jesper Skov wrote:
> >
> > >>>>> "Paleologos" == Paleologos Spanos <paleolog@ee.ucla.edu> writes:
> > Paleologos> mlqueues default scheduler). I would expect that I would
> > Paleologos> have an error or something like that because of the fact
> > Paleologos> that the 2 threads are having the same priority (4).Is it
> > Paleologos> correct or I have misunderstood something?
> >
> > The bitmap scheduler will assign a thread the closest possible
> > priority to that requested. It does not fail if the requested priority
> > is already used, it just returns another. So your threads would
> > probably have priorities 4 and 5.
>
> Jesper are you sure about that? From bitmap.cxx
>
> void Cyg_Scheduler_Implementation::add_thread(Cyg_Thread *thread)
> {
> CYG_REPORT_FUNCTION();
>
> CYG_ASSERT((CYG_THREAD_MIN_PRIORITY >= thread->priority)
> && (CYG_THREAD_MAX_PRIORITY <= thread->priority),
> "Priority out of range!");
>
> CYG_ASSERT( thread_table[thread->priority] == NULL ||
> thread_table[thread->priority] == thread,
> "Duplicate thread priorities" );
>
Yes, here's the code:
Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation
(
CYG_ADDRWORD sched_info
)
{
CYG_REPORT_FUNCTION();
#if 1
// Assign this thread's priority to the supplied sched_info
// or the next highest priority available.
priority = cyg_priority(sched_info);
while( !Cyg_Scheduler::scheduler.unique(priority) )
priority++;
#else
// Assign initial priorities to threads in descending order of
// creation.
static cyg_priority init_priority = 0;
priority = init_priority++;
#endif
}
--
Nick Garnett, eCos Kernel Architect
Red Hat, Cambridge, UK