[PATCH RFC idle 2/3] arm: Avoid invoking RCU when CPU is idle
Paul E. McKenney
paulmck at linux.vnet.ibm.com
Fri Feb 3 15:23:34 EST 2012
On Fri, Feb 03, 2012 at 03:02:55PM -0500, Steven Rostedt wrote:
> On Fri, 2012-02-03 at 11:40 -0800, Paul E. McKenney wrote:
>
> > So the idea is that if you have a trace event that is to be used in idle,
> > you use TRACE_EVENT_IDLE() rather than TRACE_EVENT() to declare that
> > trace event? That would work for me, and might make for fewer changes
> > for the architecture guys. Also, this should address the code-size
> > concerns we discussed yesterday.
> >
> > So sounds good!
> >
> > Is a DEFINE_EVENT_IDLE() also needed? Or prehaps a
> > DECLARE_EVENT_CLASS_IDLE()? My guess is "yes" for at least one of the
> > two based on include/trace/events/power.h.
>
> I'll have to take a look. I may even find a better way to do this too.
Better is always better. ;-)
> > I will keep RCU_NONIDLE() for at least a little while (reworking comments
> > to point out TRACE_EVENT_IDLE() and friends) in case there turn out to
> > be non-tracepoint uses of RCU in the idle loop.
>
> OK, I'll take a crack at this next Monday.
Sounds good!
I plan to push my stack to -next later today, but will yank my cpuidle
commit as soon as your approach is available. They do not conflict
because the rcu_idle_enter()s nest.
Thanx, Paul
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