On the effect of branch mispredictions in the Squeak VM
Andreas Raab
andreas.raab at gmx.de
Mon Jul 7 20:16:31 UTC 2003
> > John, one question about your results: How do they measure
> > up with the results coming from #tinyBenchmarks? I don't
> > think there are very many bytecodes involved either so
> > (in theory) the results obtained should be exactly in line.
> >
>
> Hi, I'm not sure what you are asking for here?
This:
> How does this compare to the overall bytecode speed we
> measure through, e.g., something like #tinyBenchmarks? The
> benchmarks contain 45 bytecodes in the loop (hand-counted;
> again someone please double-check and correct me) which means
> we have 450,000,000 bytecodes in 2.463 secs (well predicted) vs.
> 6.722 (mispredicted); resulting in:
>
> (450000000 / 2.463) truncated asStringWithCommas
> => 182,704,019 bytecodes/sec
> (450000000 / 6.722) truncated asStringWithCommas
> => 66,944,361 bytecodes/sec
>
> Comparing this to the measure obtained by #tinyBenchmarks on the same
> machine
>
> 117,323,556 bytecodes/sec
> 3,377,222 sends/sec
Cheers,
- Andreas
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