Re: [PATCH v2] perf metrics: Add literal for system TSC frequency

Peter Zijlstra
2022-05-28T14:02:47Z

On Fri, May 27, 2022 at 07:54:19AM -0700, Andi Kleen wrote:

> > This all seems bonghits inspired... and perf actually does expose the
> > tsc frequency. What do you think is in perf_event_mmap_page::time_* ?
>
>
> That's not really available to perf stat, which is the primary metrics user.

Why not? You can mmap any perf-fd (even software events) and these
fields should be filled out.

It should work on any x86 CPU that has a TSC. The only caveat is that
the kernel must not have marked the TSC unstable.

It could even work for virt -- all you need is for virt to use
native_sched_clock() instead of the paravirt nonsense.