On Fri 2016-10-28 09:07:01, Ingo Molnar wrote: > > * Pavel Machek <[email protected]> wrote: > > > +static void rh_overflow(struct perf_event *event, struct perf_sample_data > > *data, struct pt_regs *regs) > > +{ > > + u64 *ts = this_cpu_ptr(&rh_timestamp); /* this is NMI context */ > > + u64 now = ktime_get_mono_fast_ns(); > > + s64 delta = now - *ts; > > + > > + *ts = now; > > + > > + /* FIXME msec per usec, reverse logic? */ > > + if (delta < 64 * NSEC_PER_MSEC) > > + mdelay(56); > > +} > > I'd suggest making the absolute delay sysctl tunable, because 'wait 56 msecs' > is > very magic, and do we know it 100% that 56 msecs is what is needed > everywhere?
I agree this needs to be tunable (and with the other suggestions). But
this is actually not the most important tunable: the detection
threshold (rh_attr.sample_period) should be way more important.
And yes, this will all need to be tunable, somehow. But lets verify
that this works, first :-).
Thanks and best regards,
Pavel
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