Re: [PATCH] Re: Bignum performance (was: Shrinking the C core)

[Emanuel Berg <incal@dataswamp.org>]

Ihor Radchenko wrote:

> Yes, but when CBCL is orders of magnitude faster, it
> indicates something conceptually wrong in the algo.

Indeed, I'll remove it, thanks.

But my CL skills aren't at that level so someone else added
it. A strange optimization indeed, that breaks the code. Hm,
maybe not that unusual when I think about it. But that is for
normal code, not supposed benchmarks ...

So this is the explanation for the +78 875% speed disadvantage
for Elisp! As reported a long time ago when comparing Elisp
and CL. I.e., what is documented in this file

  https://dataswamp.org/~incal/emacs-init/fib.el

and discussed here (or be it gnu.emacs.help) several
months ago.

\o/

Fires up a cigar!

Always a pleasure when a mystery gets solved ... but TBH
I actually believed Elisp was that much slower. Turns out, the
CL implementation wasn't even correct. Bummer, but ultimately
good for us as it turned out.

> 3x is a matter of variation in the internal details (like
> extra type checking in Elisp that Po Lu outlined).

I'll remove the supposed optimization, and we'll take it from
there. We (you) have already improved the bignum object
allocation reuse and Mr. Möllmann solved this issue, so we
have a positive trajectory already. But 78 875% or 3x doesn't
matter in principle, we do it until we are done regardless ...

-- 
underground experts united
https://dataswamp.org/~incal