Re: possible reason for slowness with Guile 2.2?

[Jonas Hahnfeld]

Am Samstag, den 25.07.2020, 21:01 +0200 schrieb Jonas Hahnfeld:
> Continuing the discussion from 
> https://gitlab.com/lilypond/lilypond/-/merge_requests/225: One of the
> remaining reasons for slower execution times with Guile 2.2 appears to
> be the output framework. Comparing the runtime of Paper_book::output
> for MSDM.ly shows around 1 second for Guile 1.8, but more than 7
> seconds with Guile 2.2, from a total of ~30 seconds (Guile 2.2). Note
> that this includes the time for Ghostscript!
> 
> After looking into some profiles, I think this is in large parts due to
> Paper_outputter::output_stencil which eventually calls scm_eval
> from Paper_outputter::scheme_to_string. That's nothing new and has been
> suspected to be the reason. However, Han-Wen reports that switching to
> Guile 3.0, which is supposed to significantly improve the performance
> of scm_eval, does not change much and it's still slower than Guile 1.8.
> 
> As far as I currently understand, LilyPond calls scm_eval for every
> stencil which might be many (several thousands per page for MSDM.ly, up
> to ~4000 for a very crowded score of mine). To verify, I wrote attached
> micro-benchmark that calls scm_eval for the expression (+ 1 2)
> 1,000,000 times. Compiled with $ gcc -O2 -Wall eval.c -o test -lguile,
> I see ~2.7s for Guile 1.8. With -lguile-2.2 this explodes to 36s! I
> don't have an installation of Guile 3.0 around (please share if you
> have), but would expect similar results.

Nah, forgot the attachment... here we go.

eval.c
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