From: "Óscar Fuentes" <ofv@wanadoo.es>
To: emacs-devel@gnu.org
Subject: Re: Using __builtin_expect (likely/unlikely macros)
Date: Sat, 20 Apr 2019 18:28:00 +0200 [thread overview]
Message-ID: <87imv8prov.fsf@telefonica.net> (raw)
In-Reply-To: 9461246c-409b-15fd-943b-3d673c679870@cs.ucla.edu
Paul Eggert <eggert@cs.ucla.edu> writes:
> I like to see significant benefits for performance-related changes
> where the effects are not obvious. For improvements where the
> generated code is "obviously" faster (fewer and simpler instructions,
> say), I typically don't bother with measurements as my own time is
> limited too.
You will be surprised.
Modern hardware is complex.
> Agreed that 1.3% is no big deal by itself, but if one can make a
> series of 1.3% performance improvements that build on each other,
> their effects multiply and the overall effort has worthwhile practical
> benefits.
If the 1.3% improvement in performance requires non-minimal source code
complexity growth, IMHO it is not worhwile, at least on Emacs' case.
Another problem with this type of hacks is that they tend to dilute over
time, because compilers/architectures evolve. And because people change
the code without testing that those pesky declarations end in the right
place; it becomes a kind of cargo-cult.
next prev parent reply other threads:[~2019-04-20 16:28 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-15 0:15 Using __builtin_expect (likely/unlikely macros) Alex Gramiak
2019-04-15 1:18 ` Paul Eggert
2019-04-15 3:11 ` Alex Gramiak
2019-04-15 4:41 ` Paul Eggert
2019-04-16 0:16 ` Alex Gramiak
2019-04-16 2:34 ` Eli Zaretskii
2019-04-16 5:33 ` Alex Gramiak
2019-04-16 15:23 ` Eli Zaretskii
2019-04-16 15:47 ` Alex Gramiak
2019-04-16 3:42 ` Paul Eggert
2019-04-16 13:05 ` Stefan Monnier
2019-04-16 15:22 ` Paul Eggert
2019-04-16 16:10 ` Alex Gramiak
2019-04-16 17:54 ` Paul Eggert
2019-04-16 20:50 ` Alex Gramiak
2019-04-16 21:11 ` Alex Gramiak
2019-04-16 21:27 ` Stefan Monnier
2019-04-16 21:27 ` Konstantin Kharlamov
2019-04-18 8:25 ` Paul Eggert
2019-04-18 8:43 ` Konstantin Kharlamov
2019-04-18 13:47 ` Andy Moreton
2019-04-18 17:27 ` Paul Eggert
2019-04-18 17:56 ` Andy Moreton
2019-04-18 19:32 ` Paul Eggert
2019-04-19 13:45 ` Alex Gramiak
2019-04-19 13:58 ` Konstantin Kharlamov
2019-04-19 14:45 ` Alex Gramiak
2019-04-19 17:33 ` Paul Eggert
2019-04-19 20:53 ` Alex Gramiak
2019-04-20 0:05 ` Alan Mackenzie
2019-04-20 0:42 ` Paul Eggert
2019-04-20 19:46 ` Alan Mackenzie
2019-04-20 15:29 ` Andy Moreton
2019-04-20 15:57 ` Paul Eggert
2019-04-20 16:03 ` Eli Zaretskii
2019-04-20 16:11 ` Paul Eggert
2019-04-20 16:18 ` Eli Zaretskii
2019-04-20 16:57 ` Paul Eggert
2019-04-20 17:22 ` Eli Zaretskii
2019-04-20 19:13 ` Paul Eggert
2019-04-20 16:28 ` Óscar Fuentes [this message]
2019-04-20 18:58 ` Paul Eggert
2019-04-20 19:35 ` Óscar Fuentes
2019-04-20 22:54 ` Paul Eggert
2020-04-15 3:14 ` John Carter
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