Messages in this thread | | | Date | Sat, 28 May 2022 17:40:00 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2] perf metrics: Add literal for system TSC frequency |
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On Sat, May 28, 2022 at 07:50:40AM -0700, Ian Rogers wrote: > On Sat, May 28, 2022 at 7:02 AM Peter Zijlstra <peterz@infradead.org> wrote: > > > > 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. > > It will at least fail if inherit is enabled, no?
For per-task events, yes, I suppose it will. I'd forgotten about that restriction on perf_mmap() :/
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