Re: [PATCH RFC idle 2/3] arm: Avoid invoking RCU when CPU is idle

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:

quoted

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.  ;-)

quoted

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