On Tue, 2015-07-21 at 22:18 -0700, Jörn Engel wrote: > On Wed, Jul 22, 2015 at 06:36:30AM +0200, Mike Galbraith wrote: > > On Tue, 2015-07-21 at 15:07 -0700, Spencer Baugh wrote: > > > > > We have observed cases where the soft lockup detector triggered, but no > > > kernel bug existed. Instead we had a buggy realtime thread that > > > monopolized a cpu. So let's kill the responsible party and not panic > > > the entire system. > > > > If you don't tell the kernel to panic, it won't, and if you don't remove > > its leash (the throttle), your not so tame rt beast won't maul you. > > Not sure if this patch is something for mainline, but those two > alternatives have problems of their own. Not panicking on lockups can > leave a system disabled until some human come around. In many cases > that human will do no better than power-cycle. A panic reduces the > downtime.
If a realtime task goes bonkers, the realtime game is over, you're down. > And the realtime throttling gives non-realtime threads some minimum > runtime, but does nothing to help low-priority realtime threads. It > also introduces latencies, often when workloads are high and you would > like any available cpu to get through that rough spot. You can use group scheduling as a debug crutch until the little beasts are housebroken. > I don't think we have a good answer to this problem in the mainline > kernel yet. IMHO, there's no point in trying to make rt warm/fuzzy/cuddly. Just don't stuff a Hells Angel into a super-suit, that gets real ugly ;-) -Mike -- 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/