Hi,
I have made what I believe to be a better, lower-overhead
reschedule_idle() and goodness() that should fix quite a
bit of the current SMP scheduling problems.
static inline void reschedule_idle(struct task_struct * p)
{
#ifdef SMP
if (p->processor == current->processor && (p->rt_priority ||
p->counter > current->counter + 3))
current->need_resched = 1;
else if (p->counter >= ((DEF_PRIORITY * 2) / 3) || p->rt_priority)
smp_send_reschedule(p->processor);
#else
if (p->rt_priority || p->counter > current->counter + 3)
current->need_resched = 1;
#endif
}
If the process is not from the current CPU, we use a very
simple algorithm (avoiding expensive cross-CPU communication)
to determine if we should reschedule that CPU or not.
And in goodness() I changed the PROC_CHANGE_PENALTY stuff to this:
if (p->processor != this_cpu) {
weight -= PROC_CHANGE_PENALTY;
return weight;
}
The advantage of this piece of code is that processor binding
now still works if the process on the current CPU runs out of
it's timeslice (counter == 0) and a process on another CPU is
interrupted in the middle of it's slice.
In my kernel tree it's a bit more complex (because of SCHED_IDLE
stuff), but this simpler piece of code should work OK...
regards,
Rik -- the flu hits, the flu hits, the flu hits -- MORE
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