[PATCH] trace: extend trace_clock to support arch_arm clock counter

[Will Deacon]

On Fri, Dec 02, 2016 at 01:44:55PM +0530, Srinivas Ramana wrote:
> Extend the trace_clock to support the arch timer cycle
> counter so that we can get the monotonic cycle count
> in the traces. This will help in correlating the traces with the
> timestamps/events in other subsystems in the soc which share
> this common counter for driving their timers.

I'm not sure I follow this reasoning. What's wrong with nanoseconds? In
particular, the "perf" trace_clock hangs off sched_clock, which should
be backed by the architected counter anyway. What does the cycle counter in
isolation tell you, given that the frequency isn't architected?

I think I'm missing something here.

Will