On Fri, Aug 22, 2014 at 07:01:05AM +0200, Mike Galbraith wrote: > > +++ b/include/net/busy_poll.h > > @@ -109,7 +109,8 @@ static inline bool sk_busy_loop(struct sock *sk, int > > nonblock) > > cpu_relax(); > > > > } while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) && > > - !need_resched() && !busy_loop_timeout(end_time)); > > + !need_resched() && !busy_loop_timeout(end_time) && > > + nr_running_this_cpu() < 2); > >
So as has been said by now; this is horrible. We should not export nr_running like this ever. Your usage of < 2 implies this can be hit with nr_running == 0, and therefore you can also hit it with nr_running == 1 where the one is not network related and you get random delays. Worse still, you have BH (and thereby preemption) disabled, you should not _ever_ have undefined and indefinite waits like that. You also destroy any hope of dropping into lower power states; even when there's never going to be a packet ever again, also bad. All in all, a complete trainwreck. NAK. -- 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/
