Hi 9fans,
While reading src/9/port/proc.c:^runproc, I realized that the
following code is called without any lock. I would expect one in order
to walk through the each rq lists, as it is called with interrupt
enabled.
I think this would not crash the system because procs are not
dynamically allocated or freed.
I also know that locking can be a problem regarding performance.
for(rq = &runq[Nrq-1]; rq >= runq; rq--){
for(p = rq->head; p; p = p->rnext){
if(p->mp == nil || p->mp == MACHP(m->machno)
|| (!p->wired && i > 0))
goto found;
}
}
What do you think ?
Phil;
Ps: It seems runqs were designed to be individually locked. Is there
any info about the reason why all the runq are locked at once using :
lock(runq);
// ...
unlock(runq);
where we could expect (with some other changes of course) :
lock(rq);
// ...
unlock(rq);
?
