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Date: Sat, 23 Dec 2000 23:34:48 +0100
From: Pavel Machek <pavel@suse.cz>
To: Michael Chen <michaelc@turbolinux.com.cn>, alan@lxorguk.ukuu.org.uk,
        torvalds@transmeta.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: About Celeron processor memory barrier problem
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In-Reply-To: <4015029078.19991223172443@turbolinux.com.cn>; from michael chen on Thu, Dec 23, 1999 at 05:24:43PM +0800
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Hi!

> diff -Nur linux/include/asm-i386/system.h linux.new/include/asm-i386/system.h
> --- linux/include/asm-i386/system.h     Mon Dec 11 19:26:39 2000
> +++ linux.new/include/asm-i386/system.h Sat Dec 23 16:06:01 2000
> @@ -274,7 +274,14 @@
>  #ifndef CONFIG_X86_XMM
>  #define mb()   __asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
>  #else
> -#define mb()   __asm__ __volatile__ ("sfence": : :"memory")
> +#define mb()  do { \
> +       if ( cpu_has_xmm ) { \
                ~~~~~~~~~~~~~~~~~~

Cost of test may well be bigger than gain by using sfence...

Pavel

-- 
I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org
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