On Wed, Feb 09, 2022 at 10:49:20AM +0200, Adrian Hunter wrote: > diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h > index 82858b697c05..150d2b70a41f 100644 > --- a/include/uapi/linux/perf_event.h > +++ b/include/uapi/linux/perf_event.h > @@ -290,6 +290,14 @@ enum { > PERF_TXN_ABORT_SHIFT = 32, > }; > > +/* > + * If supported, clockid value to select an architecture dependent hardware > + * clock. Note this means the unit of time is ticks not nanoseconds. > + * On x86, this is provided by the rdtsc instruction, and is not > + * paravirtualized. > + */ > +#define CLOCK_PERF_HW_CLOCK 0x10000000 This steps on the clockid_t space; are we good with that? At some point there was talk of dynamic clock ids, that would complicate things more than they are today.