Re: INFO: rcu_sched self-detected stall on CPU

From: Paul E. McKenney
Date: Wed Jan 04 2017 - 11:17:25 EST


On Wed, Jan 04, 2017 at 09:16:31AM -0500, Steven Rostedt wrote:
> On Wed, 4 Jan 2017 05:46:08 -0800
> "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
>
> > I suggest enabling tracing for timers with a goal of working out why
> > the rcu_sched task is not being awakened regularly -- during a grace
> > period, it should be awakened every three jiffies or so (depending on
> > the value of HZ).
>
> Perhaps enable events for rcu, sched and irqs as well?

Good point -- but you will need to build with CONFIG_RCU_TRACE=y
to get most of the RCU events.

Thanx, Paul