Can I use LIKWID to analyze code run outside of Julia?

[sloede]

We'd like to analyze the performance of OpenFHE.jl, which internally uses CxxWrap.jl to call functions in a BB-provided C++ library (OpenFHE). However, when I measure operations that clearly take non-negligible time, I always get a RETIRED_SSE_AVX_FLOPS_ALL value of zero, and also the FLOPs/s are zero.

Is it a tool-specific issue that we just need to figure out, or is this generally not possible to do with LIKWID.jl?

cc @ArseniyKholod

[vchuravy]

LIKWID set's up performance counters, the only thing that might happen is that OpenFHE uses threads internally?

As an example to measure OpenBLAS one has to do something like

LIKWID.jl/examples/dynamic/perfmon_openblas/perfmon_openblas.jl

Line 11 in 83707df

metrics, events = perfmon("FLOPS_DP"; cpuids = 0:(nvcores - 1), autopin = false) do

[sloede]

Thanks for the hint, we will take a look 👍

[carstenbauer]

To expand: LIKWID simply tracks what happens in certain CPU cores. Whatever runs on these cores - Julia or not Julia - will be measured.

When you use @perfmon, we auto-pin the Julia threads to some CPU-cores and then measure in these cores. OpenBLAS threads or, potentially, OpenFHE threads will not be auto-pinned and will likely run on other CPU cores. Hence, they don't influence the result.

In the example that Valentin linked, we tell LIKWID.jl explicitly which CPU-cores to monitor. For example, we could track the performance of all CPU-cores or we could select those on which the relevant threads are running (we could pin the OpenBLAS threads to a specific subset of the available cores).

[ArseniyKholod]

Thank you for your help!
Am I right that the OpenBLAS example already tracks all CPU cores by using cpuids = 0:(nvcores - 1) in @perfmon?

If not, what should I do to track all the cores?
Sorry, if the answer is obvious, I am using LIKWID for the first time.)

[carstenbauer]

Am I right that the OpenBLAS example already tracks all CPU cores by using cpuids = 0:(nvcores - 1) in @perfmon?

Yes.