On Tue, Jul 23, 2013 at 08:33:31AM -0400, Don Zickus wrote: > On Tue, Jul 23, 2013 at 02:31:06AM +0200, Frederic Weisbecker wrote: > > A perf event can be used without forcing the tick to > > stay alive if it doesn't use a frequency but a sample > > period and if it doesn't throttle (raise storm of events). > > > > Since the lockup detector neither use a perf event frequency > > nor should ever throttle due to its high period, it can now > > run concurrently with the full dynticks feature. > > Thanks. Dumb question, I keep wondering if the lockup detector would be > better or worse off if it used the perf event frequency as opposed to > using a sample period? The idea is it could follow the varying cpu > frequencies better (and probably simplify some of the code too).
Right, trouble is that someone didn't consider fractional frequencies when writing the interface :/ Lowest we can go is 1 Hz while we'd want something like 0.1 Hz or smaller. Also, like the above says, that would interfere with the nohz efforts as perf needs the tick to re-compute those frequency thingies. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
