On Tue, May 20, 2014 at 1:59 PM, Tim Chen <[email protected]> wrote: > On Tue, 2014-05-20 at 13:51 -0700, Jason Low wrote: >> On Tue, May 20, 2014 at 1:17 PM, Tim Chen <[email protected]> wrote: >> >> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> > index 9b4c4f3..97132db 100644 >> > --- a/kernel/sched/fair.c >> > +++ b/kernel/sched/fair.c >> > @@ -6764,12 +6764,17 @@ static void nohz_idle_balance(struct rq *this_rq, >> > enum cpu_idle_type idle) >> > >> > rq = cpu_rq(balance_cpu); >> > >> > - raw_spin_lock_irq(&rq->lock); >> > - update_rq_clock(rq); >> > - update_idle_cpu_load(rq); >> > - raw_spin_unlock_irq(&rq->lock); >> > - >> > - rebalance_domains(rq, CPU_IDLE); >> > + /* >> > + * If time for next balance is due, >> > + * do the balance. >> > + */ >> > + if (time_after(jiffies + 1, rq->next_balance)) { >> >> Hi Tim, >> >> If we want to do idle load balancing only when it is due for a >> balance, shouldn't the above just be "if (time_after(jiffies, >> rq->next_balance))"? > > If rq->next_balance and jiffies are equal, then > time_after(jiffies, rq->next_balance) check will be false and > you will not do balance. But actually you want to balance > for this case so the jiffies+1 was used.
Hi Tim, Rik Yes, that makes sense that we want to balance if they are equal. We may also consider using "if (time_after_eq(jiffies, rq->next_balance)". Reviewed-by: Jason Low <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
