Re: [PATCH v2] rcu: Allow to eliminate softirq processing from rcutree

From: Paul E. McKenney
Date: Tue Mar 19 2019 - 12:49:26 EST


On Tue, Mar 19, 2019 at 05:24:31PM +0100, Sebastian Andrzej Siewior wrote:
> On 2019-03-19 08:59:23 [-0700], Paul E. McKenney wrote:
> > I doubt that there is any code left from my original, so I set you as
> > author.
>
> I always forward ported it the patch over the years. So if it is no
> longer what it was once so be it.

Besides, it looks very weird for me to have two Signed-off-by lines. ;-)

> > I queued this and am starting tests without setting rcunosoftirq,
> > and will run more later setting it, courtesy of --bootargs.
>
> oki.
>
> > Steve Rostedt did raise a good question about adding event tracing to
> > the park functions. I haven't really settled on an answer yet. Thoughts?
>
> It should trigger CPU hotplug events. If there was something similar for
> the softirq processing then the threaded processing should also have it.
> Please tell me which one should be added and I'm happy to add one.

In theory, the trace_rcu_utilization() should be added, just like at
the beginning and end of the function rcu_core(), but as far as I know,
no one uses that, so I actually have it on my list to remove.

Thanx, Paul