Re: [PATCH tip/core/rcu 1/2] rcu: Parallelize and economize NOCB kthread wakeups

From: Paul E. McKenney
Date: Fri Aug 08 2014 - 17:47:05 EST


On Fri, Aug 08, 2014 at 02:43:47PM -0700, Paul E. McKenney wrote:
> On Sat, Aug 09, 2014 at 12:04:24AM +0530, Amit Shah wrote:
> > On (Fri) 08 Aug 2014 [11:18:35], Paul E. McKenney wrote:
>
> [ . . . ]
>
> > > Hmmm... What happens if you boot a7d7a143d0b4cb1914705884ca5c25e322dba693
> > > with the kernel parameter "acpi=off"?
> >
> > That doesn't change anything - still hangs.
> >
> > I intend to look at this more on Monday, though - turning in for
> > today. In the meantime, if there's anything else you'd like me to
> > try, please let me know.
>
> OK, given that I still cannot reproduce it, I do need your help with
> the diagnostics. And so what sorts of diagnostics work for you in
> the hung state? Are you able to dump ftrace buffers?
>
> If you are able to dump ftrace buffers, please enable rcu:rcu_nocb_wake
> and send me the resulting trace.

And another random kernel boot parameter to try is rcu_nocb_poll.

Thanx, Paul

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