From: Nix <nix@esperi.org.uk>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: rudalics@gmx.at, Eli Zaretskii <eliz@gnu.org>,
eggert@cs.ucla.edu, emacs-devel@gnu.org
Subject: Re: Tooltips GC overhead
Date: Sat, 08 Aug 2015 14:41:38 +0100 [thread overview]
Message-ID: <87io8plwx9.fsf@esperi.org.uk> (raw)
In-Reply-To: <jwvfv3z5x8k.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Tue, 04 Aug 2015 03:31:52 -0400")
On 4 Aug 2015, Stefan Monnier told this:
>>> The problem is that it would slow down functions like `cons'.
>> I don't see why it has to.
>
> I don't see how it wouldn't have to ;-)
>
>> And we could do that only when the memory profiler is invoked.
>
> AFAICT it would require an extra test somewhere in Fcons, and that
> test will always have to be performed.
The cost you're trying to defend against here is a mispredicted branch
and corresponding pipeline stall, so if you mark it with
__builtin_expect() (or analogue in other compilers) you can make the
'profiler off' case the predicted branch, and its cost when off should
drop to nearly zero.
(Or so it seems to me.)
--
NULL && (void)
next prev parent reply other threads:[~2015-08-08 13:41 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-28 12:45 Tooltips GC overhead martin rudalics
2015-07-28 13:53 ` Eli Zaretskii
2015-07-28 15:09 ` martin rudalics
2015-07-28 23:51 ` Stefan Monnier
2015-07-29 7:18 ` martin rudalics
2015-07-29 14:29 ` Paul Eggert
2015-07-29 15:40 ` martin rudalics
2015-07-29 16:33 ` Eli Zaretskii
2015-07-29 18:05 ` martin rudalics
2015-07-29 21:15 ` Paul Eggert
2015-07-30 6:00 ` martin rudalics
2015-07-30 7:08 ` martin rudalics
2015-07-30 7:19 ` Paul Eggert
2015-07-30 9:05 ` martin rudalics
2015-07-30 16:36 ` Eli Zaretskii
2015-07-30 19:53 ` martin rudalics
2015-07-30 23:09 ` Stefan Monnier
2015-07-30 23:33 ` Drew Adams
2015-07-31 6:48 ` Eli Zaretskii
2015-07-31 6:47 ` Eli Zaretskii
2016-03-06 9:21 ` martin rudalics
2016-03-08 8:02 ` martin rudalics
2015-08-01 10:49 ` martin rudalics
2015-08-03 10:34 ` Stefan Monnier
2015-08-03 14:56 ` Eli Zaretskii
2015-08-03 21:13 ` Stefan Monnier
2015-08-04 2:38 ` Eli Zaretskii
2015-08-04 7:31 ` Stefan Monnier
2015-08-04 13:28 ` Eli Zaretskii
2015-08-07 14:52 ` Stefan Monnier
2015-08-07 15:23 ` Eli Zaretskii
2015-08-07 17:26 ` Stefan Monnier
2015-08-07 18:20 ` Eli Zaretskii
2015-08-07 21:25 ` Stefan Monnier
2015-08-08 6:46 ` Eli Zaretskii
2015-08-08 7:01 ` David Kastrup
2015-08-07 18:26 ` Paul Eggert
2015-08-07 18:59 ` Eli Zaretskii
2015-08-08 13:41 ` Nix [this message]
2015-08-08 16:10 ` Stefan Monnier
2015-08-08 16:13 ` David Kastrup
2015-08-10 17:05 ` Nix
2015-08-10 17:44 ` David Kastrup
2015-07-29 16:45 ` Paul Eggert
2015-07-29 18:05 ` martin rudalics
2015-07-29 21:17 ` Paul Eggert
2015-07-30 6:00 ` martin rudalics
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/emacs/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87io8plwx9.fsf@esperi.org.uk \
--to=nix@esperi.org.uk \
--cc=eggert@cs.ucla.edu \
--cc=eliz@gnu.org \
--cc=emacs-devel@gnu.org \
--cc=monnier@iro.umontreal.ca \
--cc=rudalics@gmx.at \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).