On Wed, 28 Feb 2024 07:15:42 -0800 Paul E. McKenney wrote: > > > Another complication is that although CONFIG_PREEMPT_RT kernels are > > > built with CONFIG_PREEMPT_RCU, the reverse is not always the case. > > > And if we are not repolling, don't we have a high probability of doing > > > a voluntary context when we reach napi_thread_wait() at the beginning > > > of that loop? > > > > Very much so, which is why adding the cost of rcu_softirq_qs() > > for every NAPI run feels like an overkill. > > Would it be better to do the rcu_softirq_qs() only once every 1000 times > or some such? Or once every HZ jiffies? > > Or is there a better way? Right, we can do that. Yan Zhai, have you measured the performance impact / time spent in the call?
