Thread question

[Steve Holle]

I'm having problems with a thread getting starved, I believe, and I'm 
looking for some help on how to fix it.  This is probably a threading 101 
question but please stick with me.

I have two threads that never block, call them threads 1A and 1B, and are 
defined as follows (with different names) :
rtems_status_code status = rtems_task_create( name,
         100,
         RTEMS_MINIMUM_STACK_SIZE * 2,
         RTEMS_PREEMPT | RTEMS_TIMESLICE,
         RTEMS_FLOATING_POINT | RTEMS_LOCAL,
         &tid );

I have a number of other threads that block, call them 2A thru 2?, and are 
defined similar to the following :
rtems_task_set_priority (RTEMS_SELF, RTEMS_CURRENT_PRIORITY, &my_priority_w);
sc = rtems_task_create (rtems_build_name ('S', 'A', 'S', 'W'),
   my_priority_w,
   8*1024,
   RTEMS_PREEMPT | RTEMS_NO_TIMESLICE | RTEMS_NO_ASR | 
RTEMS_INTERRUPT_LEVEL(0),
   RTEMS_NO_FLOATING_POINT|RTEMS_LOCAL,
   &tidw);

The latest thread I've added is a streaming audio thread and adds a fair 
amount of overhead.  Threads 1A and 1B run fine until I enable the 
streaming audio thread at which point thread 1B stops responding.  If I 
only handle, say every tenth streaming audio sample thread 2A, 1B starts 
working.  And it's not a slow degradation but a sudden cutoff.

If I disable task 1A, 1B keeps running even with the streaming audio running.

I assumes that since 1A and 1B where set up to timeslice that whatever time 
was left 1A and 1B would get serviced.  That is obviously a false assumption.

Any ideas?


Steve Holle
Link Communications, Inc.
1035 Cerise Rd.
Billings, MT  59101
sholle at link-comm.com