Re: [PATCH] kprobes: Fix to delay the kprobes jump optimization

From: Paul E. McKenney
Date: Fri Feb 19 2021 - 14:46:26 EST


On Fri, Feb 19, 2021 at 02:14:29PM -0500, Steven Rostedt wrote:
> On Fri, 19 Feb 2021 10:18:11 -0800
> "Paul E. McKenney" <paulmck@xxxxxxxxxx> wrote:
>
> > We can further prevent entry into dyntick-idle state until
> > the ksoftirqd kthreads have been spawned, which means that if softirq
> > handlers must be deferred, they will be resumed within one jiffy by the
> > next scheduler-clock interrupt.
>
> Why not just prevent entry into dyntick-idle state until the system is
> finished booting? As you said; There should be no latency-sensitive
> applications running, until after we started the system.

Exactly, and that is the effect of patch to rcu_needs_cpu() that I just
now posted.

Ah, your point is that if the tick keeps running, there is no need to
modify softirq? Good point, and I will test that, thank you!!!

Thanx, Paul