The standard says a SCHED_FIFO task only gives up the processor if it
blocks, yields, or changes its priority.  

The counter is not really used by SCHED_FIFO tasks, however the
update_process_times() code will set the "need_resched" flag on a
SCHED_FIFO task, even though schedule() effectively ignores the entry. 
The attached patch addresses these issues by setting the counter to -100
for SCHED_FIFO tasks and "teaching" update_process_timers() to not count
down negative counters.  This avoids the calling of schedule() every
jiffie while a SCHED_FIFO task is running.

I tried to keep the change to recalculate confined to only the data
elements it was already touching, however, the standard really doesn't
allow recalculate to touch the SCHED_RR counter.  A standard conforming
test would restrict recalculate to only SCHED_OTHER tasks.

Comments?

George