From: Jonathan Wakely <jwakely@redhat.com>
To: Jason Merrill <jason@redhat.com>
Cc: Matthias Kretz <m.kretz@gsi.de>,
"Richard Earnshaw (lists)" <Richard.Earnshaw@arm.com>,
"libstdc++" <libstdc++@gcc.gnu.org>,
gcc-patches List <gcc-patches@gcc.gnu.org>,
GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCH] c++: implement C++17 hardware interference size
Date: Fri, 16 Jul 2021 17:54:30 +0100 [thread overview]
Message-ID: <CACb0b4kp-X+t7+Yuf9VwaX6cBL-jaRoVBE-EsZCyv+S0LQAKCw@mail.gmail.com> (raw)
In-Reply-To: <CADzB+2k2mX0_9xuBMqkBbpptUFYKQcqUCsmtKe5cDi=ahOjWCw@mail.gmail.com>
On Fri, 16 Jul 2021 at 16:33, Jason Merrill wrote:
> Adjusting them based on tuning would certainly simplify a significant use
> case, perhaps the only reasonable use. Cases more concerned with ABI
> stability probably shouldn't use them at all. And that would mean not
> needing to worry about the impossible task of finding the right values for
> an entire architecture.
But it would be quite a significant change in behaviour if -mtune
started affecting ABI, wouldn't it?
> I'm thinking about warning by default for any use of the variables without
> explicitly specifying their values on the command line. Users could disable
> the warning if they're happy using whatever the defaults happen to be.
I like that suggestion.
Maybe the warning could suggest optimal values based on the current
-mtune flag. That way -mtune wouldn't need to alter ABI, but by
combining -mtune with explicit values for the variables you get the
best performance. And -mtune without overriding the default values
preserves ABI.
next prev parent reply other threads:[~2021-07-16 16:54 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210716023656.670004-1-jason@redhat.com>
2021-07-16 2:41 ` Jason Merrill
2021-07-16 2:48 ` Noah Goldstein
2021-07-16 11:17 ` Jonathan Wakely
2021-07-16 13:27 ` Richard Earnshaw
2021-07-16 13:26 ` Jonathan Wakely
2021-07-16 15:12 ` Matthias Kretz
2021-07-16 15:30 ` Jason Merrill
2021-07-16 16:54 ` Jonathan Wakely [this message]
2021-07-16 18:43 ` Jason Merrill
2021-07-16 19:26 ` Matthias Kretz
2021-07-16 19:58 ` Jonathan Wakely
2021-07-17 8:14 ` Matthias Kretz
2021-07-17 13:32 ` Jonathan Wakely
2021-07-17 13:54 ` Matthias Kretz
2021-07-17 21:37 ` Jason Merrill
2021-07-19 9:41 ` Richard Earnshaw
2021-07-20 16:43 ` Jason Merrill
2021-07-20 18:05 ` Thomas Rodgers
2021-07-16 17:20 ` Noah Goldstein
2021-07-16 19:37 ` Matthias Kretz
2021-07-16 21:23 ` Noah Goldstein
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
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CACb0b4kp-X+t7+Yuf9VwaX6cBL-jaRoVBE-EsZCyv+S0LQAKCw@mail.gmail.com \
--to=jwakely@redhat.com \
--cc=Richard.Earnshaw@arm.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=jason@redhat.com \
--cc=libc-alpha@sourceware.org \
--cc=libstdc++@gcc.gnu.org \
--cc=m.kretz@gsi.de \
/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.
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).