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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.