From: Chuck Ebbert <76306.1226@compuserve.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Hugh Dickins <hugh@veritas.com>, Ingo Molnar <mingo@redhat.com>,
Linus Torvalds <torvalds@osdl.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [patch] fix i386 mutex fastpath on FRAME_POINTER && !DEBUG_MUTEXES
Date: Wed, 11 Jan 2006 03:24:10 -0500 [thread overview]
Message-ID: <200601110327_MC3-1-B5A3-6E0E@compuserve.com> (raw)
In-Reply-To: <20060110210744.GA8850@elte.hu>
On Tue, 10 Jan 2006 at 22:07:44 +0100, Ingo Molnar wrote:
> --- linux.orig/include/asm-i386/mutex.h
> +++ linux/include/asm-i386/mutex.h
> @@ -28,7 +28,13 @@ do { \
> \
> __asm__ __volatile__( \
> LOCK " decl (%%eax) \n" \
> - " js "#fail_fn" \n" \
> + " js 2f \n" \
> + "1: \n" \
> + \
> + LOCK_SECTION_START("") \
> + "2: call "#fail_fn" \n" \
> + " jmp 1b \n" \
> + LOCK_SECTION_END \
> \
> :"=a" (dummy) \
> : "a" (count) \
But now it's inefficient again.
Why not this:
LOCK " decl (%%eax) \n" \
" jns 1f \n" \
" call "#fail_fn" \n" \
"1: \n" \
\
:"=a" (dummy) \
: "a" (count) \
Will the extra taken forward conditional jump in the fastpath cause much of
a slowdown?
--
Chuck
Currently reading: _Olympos_ by Dan Simmons
next reply other threads:[~2006-01-11 8:27 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-11 8:24 Chuck Ebbert [this message]
2006-01-11 10:13 ` Ingo Molnar
-- strict thread matches above, loose matches on Subject: below --
2006-01-12 17:53 Chuck Ebbert
2006-01-10 17:44 i386 FRAME_POINTER needs DEBUG_MUTEXES Hugh Dickins
2006-01-10 21:07 ` [patch] fix i386 mutex fastpath on FRAME_POINTER && !DEBUG_MUTEXES Ingo Molnar
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