On Tue, Sep 16, 2025, at 15:20 CDT, Matthias Maier <[email protected]> wrote:
>> C program that I assume is the worst case for FlexiBLAS: doing >> 100,000,000 scalar (1x1 matrix) multiplications with repeated calls to >> cblas_dgemm(). These numbers obviously fluxuate, but they are >> representative: >> >> * netlib: 8.51s >> * openblas: 13.75s >> * flexiblas (netlib): 24.71s >> * flexiblas (openblas): 27.45s > So this is basically measuring the pure function call overhead > introduced by flexiblas which amounts to roughly 15s for 100,000,000 > repeated calls to cblas_dgemm(). This is pretty good I would say. Just for reference what we are talking about: 100,000,000 scalar multiplications (with 2 cycle inverse throughput) on a core with 3GHz will amount to 0.07s. So calling into blas for that adds roundabout a factor ~100 inefficiency. Flexiblas will worsen that to a factor ~300. Best, Matthias
