From: Paul Eggert <eggert@cs.ucla.edu>
To: emacs-devel@gnu.org
Subject: Re: Using __builtin_expect (likely/unlikely macros)
Date: Sat, 20 Apr 2019 15:54:23 -0700 [thread overview]
Message-ID: <40799fea-4ef7-6a43-f2e6-e9df684b71f2@cs.ucla.edu> (raw)
In-Reply-To: <87zhoko4fg.fsf@telefonica.net>
Óscar Fuentes wrote:
> I'm pretty sure that
> the speedup will vanish as code is modified and compilers and CPUs
> change.
I agree that if you disable GCC optimization or do lots of other
plausible-but-low-performance things, that patch will not help performance.
However, I'm skeptical that the patch would make performance worse in ordinary
production builds on current Emacs platforms. And I wasn't surprised that the
patch was a significant (albeit small) win on the platform I tested on, because
I looked at the machine code that it generated and I knew something of my
platform's architecture.
Of course I could be unpleasantly surprised about how well this performance win
generalizes to other platforms - and as I wrote, I am often surprised. To become
surprised, though, we need to see some numbers.
> I'm far from being a naive programmer.
I didn't think you were naive, and apologize if my comments could be interpreted
that way. My comments were intended only to make it clear that I'm not a naive
programmer.
next prev parent reply other threads:[~2019-04-20 22:54 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
2019-04-20 18:58 ` Paul Eggert
2019-04-20 19:35 ` Óscar Fuentes
2019-04-20 22:54 ` Paul Eggert [this message]
2020-04-15 3:14 ` John Carter
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