From: "Jan Beulich" <JBeulich@suse.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Ingo Molnar" <mingo@kernel.org>, <tglx@linutronix.de>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [tip:x86/asm] x86: Prefer TZCNT over BFS
Date: Tue, 18 Sep 2012 07:40:52 +0100 [thread overview]
Message-ID: <50583394020000780009BF8B@nat28.tlf.novell.com> (raw)
In-Reply-To: <50575855.8040308@zytor.com>
>>> On 17.09.12 at 19:05, "H. Peter Anvin" <hpa@zytor.com> wrote:
> Honestly, I don't see a reason to not do this unconditionally. On
> anything but (pre-686-era) extremely old CPUs the cost of the extra
> prefix is zero. On the really old CPUs the cost of the BSF instruction
> will dwarf the penalty cycle for the extra prefix, so the whole
> mechanism around doing it conditionally seems pointless.
I certainly don't mind re-submitting with the whole thing made
unconditional (implying that the prior version would be dropped
in any case).
Jan
prev parent reply other threads:[~2012-09-18 6:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-10 11:24 [PATCH] x86: prefer tzcnt over bsf Jan Beulich
2012-09-14 6:23 ` [tip:x86/asm] x86: Prefer TZCNT over BFS tip-bot for Jan Beulich
2012-09-14 21:14 ` Linus Torvalds
2012-09-14 21:32 ` Borislav Petkov
2012-09-17 7:41 ` Jan Beulich
2012-09-17 10:00 ` Ingo Molnar
2012-09-17 10:58 ` Jan Beulich
2012-09-17 17:00 ` Linus Torvalds
2012-09-17 17:05 ` H. Peter Anvin
2012-09-17 17:13 ` Linus Torvalds
2012-09-18 6:40 ` Jan Beulich [this message]
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=50583394020000780009BF8B@nat28.tlf.novell.com \
--to=jbeulich@suse.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
/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 NNTP newsgroup(s).