Re: sched_rt_period_timer causing large latencies

From: Peter Zijlstra
Date: Thu Apr 05 2018 - 04:27:49 EST

On Thu, Apr 05, 2018 at 09:11:38AM +1000, Nicholas Piggin wrote:
> Hi,
> I'm seeing some pretty big latencies on a ~idle system when a CPU wakes
> out of a nohz idle. Looks like it's due to the taking a lot of remote
> locks and cache lines. irqoff trace:

On RT I think we default RT_RUNTIME_SHARE to false, maybe we should do
the same for mainline. It's always been a dodgy feature and if we ever
figure out how to do FIFO servers this code will be deleted entirely.