On Sun Nov 30 20:27:15 PST 2014, [email protected] wrote:
> That definitely seems incorrect to me. Since rebalance is only called
> on mach0, as it loops through the global run queue, it will skip
> processes that are not on mach0, so I think you are correct. (This was
> fixed on the mqs version of the nix scheduler; every mach calls
> rebalance to take care of their respective run queues.)
yes, that does fix that (yeah!) but i think there are two other issues.
(1) it doesn't recognize that it's not worth rebalancing if there are just
a few processes in the runq, and
(2) it quits before scanning them all.
the second is comprehensibly fixable, while the first ... i just used a
gnarly herustic.
without the benefit of your gsoc work, or enough thought, i came up
with the following. although i like gotos just as much as the next guy,
this is a case where they were not helpful. it's still not clear to me why
p->mp != m makes any difference. (er, MACHP(m->machno) on 386).
static void
rebalance(void)
{
Mpl pl;
int pri, npri;
Tick t;
Sched *sch;
Schedq *rq;
Proc *p, *next;
sch = m->sch;
t = m->ticks;
if(t - sch->balancetime < HZ/2)
return;
sch->balancetime = t;
if(sch->nrdy < sch->nmach/2) /* suspect hurestic */
return;
for(pri=0, rq=sch->runq; pri<Npriq; pri++, rq++){
for(p = rq->head; p != nil; p = next){
next = p->rnext;
if(p->mp != m)
continue;
if(pri == p->basepri)
continue;
updatecpu(p);
npri = reprioritize(p);
if(npri != pri){
pl = splhi();
p = dequeueproc(sch, rq, p);
if(p != nil)
queueproc(sch, &sch->runq[npri], p);
splx(pl);
}
}
}
}
- erik
