Re: Announcing Dolt, a drop-in Libtool replacement which cuts build times in half

[Ralf Wildenhues]

* Josh Triplett wrote on Wed, Apr 09, 2008 at 06:02:36PM CEST:
> Ralf Wildenhues wrote:
> > 
> > Curious: can you please state which Libtool version you timed against,
> > and if not 2.2.x, redo timing against 2.2.2?  Not that I expect wonders,
> > but I expect something better than what you measured.
> 
> I tested against 1.5.26.  I'll give 2.2.2 a shot and see what I find.
> However, when I looked at 2.2.2, it still seems to have a
> multi-thousand-line shell script; do you just expect the benefit to
> come from the new shell-specific optimizations?

Partly, yes.  And Ross showed that we already got half the way, and yes,
the compile mode improvements are the biggest:
<http://thread.gmane.org/gmane.linux.debian.devel.general/126905/focus=9125>
Libtool 2.2.2 in compile mode uses only 6 forks in compile mode if your
shell has XSI features.

Another thing to keep in mind is to put func_mode_compile early in the
script, and outside of conditionals, so that the shell doesn't even have
to parse anything below that.  That gave the biggest speedup on
GNU/Linux (where forks are relatively cheap).
<http://thread.gmane.org/gmane.comp.gnu.libtool.patches/7230>

That message also shows timings for a separated libtool-link script,
beyond which I then saw no further performance improvements.  I guess
I could try to dig out that old patch (which was never applied).


Also, I see two more low-hanging fruits at the moment.  Will follow up
with patches later tonight or tomorrow night.

Cheers,
Ralf