On Tue, Dec 08, 2020 at 10:24:09AM -0800, Paul E. McKenney wrote: > > It reduces the code scope running with BH disabled. > > Also narrowing down helps to understand what it actually protects. > > I thought that you would call out unnecessarily delaying other softirq > handlers. ;-) > > But if such delays are a problem (and they might well be), then to > avoid them on non-rcu_nocb CPUs would instead/also require changing the > early-exit checks to check for other pending softirqs to the existing > checks involving time, need_resched, and idle. At which point, entering and > exiting BH-disabled again doesn't help, other than your point about the > difference in BH-disabled scopes on rcu_nocb and non-rcu_nocb CPUs. Wise observation! > > Would it make sense to exit rcu_do_batch() if more than some amount > of time had elapsed and there was some non-RCU softirq pending? > > My guess is that the current tlimit checks in rcu_do_batch() make this > unnecessary. Right and nobody has complained about it so far. But I should add a comment explaining the reason for the BH-disabled section in my series. Thanks. > > Thoughts? > > Thanx, Paul
