Messages in this thread | | | From | Namhyung Kim <> | Date | Tue, 11 Oct 2022 20:58:40 -0700 | Subject | Re: [RFC/PATCHSET 00/19] perf stat: Cleanup counter aggregation (v1) |
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On Tue, Oct 11, 2022 at 4:57 AM Andi Kleen <ak@linux.intel.com> wrote: > > > >> My main concern would be subtle regressions since there are so many > >> different combinations and way to travel through the code, and a lot of > >> things are not covered by unit tests. When I worked on the code it was > >> difficult to keep it all working. I assume you have some way to > >> enumerate them all and tested that the output is identical? > > Right, that's my concern too. > > > > I have tested many combinations manually and checked if they > > produced similar results. > > I had a script to test many combinations, but had to check the output > manually > > > > But the problem is that I cannot test > > all hardwares and more importantly it's hard to check > > programmatically if the output is the same or not. > > Can use "dummy" or some software event (e.g. a probe on some syscall) to > get stable numbers. I don't think we need to cover all hardware for the > output options, the different events should be similar, but need some > coverage for the different aggregation. Or we could add some more tool > events just for testing purposes, that would allow covering different > core scopes etc. and would easily allow generating known counts.
Even if we can get a stable number, it still needs to know cpu topology for different aggregation modes to verify the count. Also I'm afraid that cpu hotplug can affect the aggregation.
Thanks, Namhyung
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