GNU bug report logs - #69480
Emacs Lisp needs, for its great 'native-compile', 'declare' and 'the' for fixnums and arrays.

Previous Next

Full log

View this message in rfc822 format

From: Eli Zaretskii <eliz <at> gnu.org>
To: Stephen Berman <stephen.berman <at> gmx.net>, Andrea Corallo <acorallo <at> gnu.org>
Cc: robertstephenboyer <at> gmail.com, 69480 <at> debbugs.gnu.org
Subject: bug#69480: Emacs Lisp needs, for its great 'native-compile', 'declare' and 'the' for fixnums and arrays.
Date: Fri, 01 Mar 2024 14:34:36 +0200

> From: Stephen Berman <stephen.berman <at> gmx.net>
> Cc: Robert Boyer <robertstephenboyer <at> gmail.com>,  69480 <at> debbugs.gnu.org
> Date: Fri, 01 Mar 2024 12:28:30 +0100
> 
> On Thu, 29 Feb 2024 22:10:27 +0200 Eli Zaretskii <eliz <at> gnu.org> wrote:
> 
> > It takes 16.7 sec on my system.
> 
> I was curious to see how long it takes on my system, compared to the
> byte-compiled and uncompiled files, and the results surprised me.
> First, I visited the file eratosthenes.el, ran `eval-buffer' and then
> `M-: (benchmark-run nil (build-sieve (expt 10 8)))', with this result:
> 
> (143.326808051 1 0.344846223)
> 
> Then I ran `M-: (progn (emacs-lisp-native-compile-and-load)
> (benchmark-run nil (build-sieve (expt 10 8))))', with this result:
> 
> (37.457440511 1 0.36922945500000004)
> 
> The native compilation also produced a byte-compiled file
> eratosthenes.elc, so I then loaded that file and again ran `M-:
> (benchmark-run nil (build-sieve (expt 10 8)))', with this result:
> 
> (21.854069551000002 1 0.3595161699999999)
> 
> I was surprised that this was much faster than the run with native
> compilation, but I thought perhaps this was due to the time spent
> producing both the native and byte-compiled files (though more than 15
> seconds for that seemed unlikely), so I ran `M-: (progn
> (emacs-lisp-native-compile-and-load) (benchmark-run nil (build-sieve
> (expt 10 8))))' again, which just loaded the already native-compiled
> file (and updated its timestamp), but the result was practically the
> same as the first time:
> 
> (37.095767574 1 0.36986937500000017)
> 
> Why is the timing with native compilation so much slower than with byte
> compilation?

That's not what I see here (in an optimized build of Emacs 29.2).  On
my system, the byte-compiled version and the native-compiled version
yield almost the same times: 16.12 vs 16.5 sec.  The way native
compilation is currently implemented, whether it produces a
significant speedup depends on the actual Lisp code, and having the
same or even slightly slower performance is not unheard of.  So I
don't see anything unexpected on my system, at least in Emacs 29.

Adding Andrea, in case he has comments to this.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.