Messages in this thread | | | Date | Fri, 3 Apr 2009 11:05:16 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] tracing/filters: allow event filters to be set only when not tracing |
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On Fri, Apr 03, 2009 at 12:43:15PM -0400, Steven Rostedt wrote: > > On Fri, 3 Apr 2009, Ingo Molnar wrote: > > > > > > My kneejerk reaction is "why would anyone want to trace the idle > > > loop?" > > > > heh :-) > > > > Idle enter/exit events are useful to tune power use for example. The > > more events we have there, the more we prevent the CPU from slowly > > going into deep sleep mode.
But we could in principle trace idle enter/exit from the scheduler, correct?
That said, it would be possible to allow much of the idle loop to contain RCU read-side critical sections, but this requires putting rcu_qsctr_inc() in each and every idle loop, plus catching the cases where idle loops shut down the CPU. Note that this applies to synchronize_sched() as well as synchronize_rcu().
> I can say I use it a lot. I'm still needing a way to set the function pid > recorder to 0 since the conversion to the pid structure. There are times > I only want to trace the interrupts that happen in the idle loop.
It would be OK to trace the interrupts, just not the idle loop itself.
Thanx, Paul
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