Re: [Caml-list] flambda optimization settings

[Gabriel Scherer <gabriel.scherer@gmail.com>]

My understanding is that -Oclassic does not compile with the
pre-flambda compiler, but rather it tunes flambda heuristics to behave
more or less like the other compiler. The goal was to reach a point in
the optimization-vs-compile-time spectrum that is comparable to the
other compiler, but I'm not sure it was actually reached yet.

Thus, it would be interesting and important to also compare with the
code produced by a 4.03 switch compiled without flambda.

(Also, it would be interesting to have reports on compile time.)

On Thu, May 12, 2016 at 12:13 PM, Nils Becker
<nils.becker@bioquant.uni-heidelberg.de> wrote:
> hi,
>
> i'm happy to report one more data point on flambda speedup.
>
> (best of 3, wall clock time, 4 cores running with parmap)
> -Oclassic 18.5s
> -O2       17.0s
> -O3       14.2s
>
> so, a nice 20% speedup with no work.
>
> this brings me to my question: given that O2 vs O3 does seem to matter,
> is it actually important at what optimization level linked libraries are
> compiled on a +flambda switch?
> who controls that, the package author or the user?
>
> n.
>
>
> ps, full disclosure:
>
> this is based on code that does stochastic simulation (basically
> euler-maruyama forward integration), uses Gsl for heavy random number
> generation but also does some floating point arithmetic in the inner
> loop, and uses exceptions as part of control flow.
>
>
>
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