Re: lots of brief rcu stalls.

Paul E. McKenney
2013-12-05T17:31:08Z

On Thu, Dec 05, 2013 at 12:15:50PM -0500, Dave Jones wrote:
> On Thu, Dec 05, 2013 at 08:49:12AM -0800, Paul E. McKenney wrote:
>
> > But what workload are you running that causes this? The only way I
> > can think of to make this happen requires that you have at least one
> > CPU spending more than 21 seconds running continuously in kernel mode.
> > Is that what you are doing, or have you come up with some other creative
> > way for this to happen? In the latter case, I would really like to know
> > about it in case it exposes yet another flaw in my RCU design. ;-)
>
> just the regular trinity runs, so it could be anything.
> (Running a few instances of it, with a couple dozen child processes each to drive up the loadavg)

Well, trinity has caused kernel-mode execution periods in excess of
21 seconds in the past, so I will assume that this is the cause until
further notice.

> if only I had a trace or something that I could start to guess at what was happening :)

Maybe creating such a trace would expose additional bugs. ;-)

Thanx, Paul