From: "H. Peter Anvin" <hpa@zytor.com>
To: Wedson Almeida Filho <wedsonaf@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] x86: Use asm-goto to implement mutex fast path on x86-64
Date: Fri, 28 Jun 2013 07:14:58 -0700 [thread overview]
Message-ID: <51CD9A62.3020404@zytor.com> (raw)
In-Reply-To: <1372420245-60021-1-git-send-email-wedsonaf@gmail.com>
On 06/28/2013 04:50 AM, Wedson Almeida Filho wrote:
> The new implementation allows the compiler to better optimize the code; the
> original implementation is still used when the kernel is compiled with older
> versions of gcc that don't support asm-goto.
>
> Compiling with gcc 4.7.3, the original mutex_lock() is 60 bytes with the fast
> path taking 16 instructions; the new mutex_lock() is 42 bytes, with the fast
> path taking 12 instructions.
>
> The original mutex_unlock() is 24 bytes with the fast path taking 7
> instructions; the new mutex_unlock() is 25 bytes (because the compiler used
> a 2-byte ret) with the fast path taking 4 instructions.
>
> The two versions of the functions are included below for reference.
>
As Ingo said, looks very nice. However, it is really too late for Linux
3.11, so I'm going to put it on a queue I already have for 3.12.
-hpa
next prev parent reply other threads:[~2013-06-28 14:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-28 11:50 [PATCH v2] x86: Use asm-goto to implement mutex fast path on x86-64 Wedson Almeida Filho
2013-06-28 14:14 ` H. Peter Anvin [this message]
2013-06-29 6:35 ` Wedson Almeida Filho
2013-07-05 14:24 ` [tip:x86/asm] " tip-bot for Wedson Almeida Filho
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=51CD9A62.3020404@zytor.com \
--to=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=wedsonaf@gmail.com \
--cc=x86@kernel.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).