On Thu, Apr 24, 2014 at 12:32:31PM +0100, Peter Zijlstra wrote: > On Thu, Apr 24, 2014 at 11:30:59AM +0100, Morten Rasmussen wrote: > > On Thu, Apr 24, 2014 at 02:30:35AM +0100, Jason Low wrote: > > > @@ -6704,7 +6703,12 @@ static int idle_balance(struct rq *this_rq) > > > interval = msecs_to_jiffies(sd->balance_interval); > > > if (time_after(next_balance, sd->last_balance + interval)) > > > next_balance = sd->last_balance + interval; > > > - if (pulled_task) > > > + > > > + /* > > > + * Stop searching for tasks to pull if there are > > > + * now runnable tasks on this rq. > > > + */ > > > + if (pulled_task || this_rq->nr_running > 0) > > > > Should this be cfs tasks instead? > > > > + if (pulled_task || this_rq->cfs.h_nr_running > 0) > > > > 3.15-rc2 commit 35805ff8f4fc535ac85330170d3c56829c87c677 seems to > > indicate that using rq->nr_running may lead to trouble. > > > > The other two patches look good to me. > > No, this really wants to be nr_running, we want to bail the idle > balancer when there's anything runnable present. > > Note how out: is very careful to return -1 (which results in RETRY_TASK) > when rq->nr_running != rq->cfs.h_nr_running. > > That same out: test also makes problem that commit fixes impossible > again.
I should have done my homework properly. I may be missing something, but don't we risk bailing out of idle balance if there is a throttled rt task and go straight to idle? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
