From: Dave Jones <davej@redhat.com>
To: Nick Piggin <npiggin@suse.de>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andi Kleen <ak@suse.de>
Subject: Re: [rfc][patch 2/3] x86: fix IO write barriers
Date: Thu, 4 Oct 2007 13:32:03 -0400 [thread overview]
Message-ID: <20071004173203.GC5828@redhat.com> (raw)
In-Reply-To: <20071004052258.GB15131@wotan.suse.de>
On Thu, Oct 04, 2007 at 07:22:58AM +0200, Nick Piggin wrote:
> -#ifdef CONFIG_X86_OOSTORE
> -/* Actually there are no OOO store capable CPUs for now that do SSE,
> - but make it already an possibility. */
> -#define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
> -#else
> -#define wmb() __asm__ __volatile__ ("": : :"memory")
> -#endif
> -
> #ifdef CONFIG_SMP
> #define smp_mb() mb()
> #define smp_rmb() rmb()
> -#define smp_wmb() wmb()
> +#ifdef CONFIG_X86_OOSTORE
> +# define smp_wmb() wmb()
> +#else
> +# define smp_wmb() barrier()
> +#endif
The only vendor that ever implemented OOSTOREs was Centaur, and they
only did in the Winchip generation of the CPUs. When they dropped it
from the C3, I asked whether they intended to bring it back, and the
answer was "extremely unlikely".
So we can probably just drop that "just in case" clause above, and just
do..
#define smp_wmb() barrier()
Dave
--
http://www.codemonkey.org.uk
next prev parent reply other threads:[~2007-10-04 17:32 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-04 5:21 [rfc][patch 1/3] x86_64: fence nontemproal stores Nick Piggin
2007-10-04 5:22 ` [rfc][patch 2/3] x86: fix IO write barriers Nick Piggin
2007-10-04 17:32 ` Dave Jones [this message]
2007-10-04 17:53 ` Andi Kleen
2007-10-04 18:10 ` Dave Jones
2007-10-04 18:21 ` Andi Kleen
2007-10-04 18:41 ` Dave Jones
2007-10-04 18:58 ` Andi Kleen
2007-10-04 19:08 ` Dave Jones
2007-10-04 20:52 ` Alan Cox
2007-10-04 5:23 ` [rfc][patch 3/3] x86: optimise barriers Nick Piggin
2007-10-12 8:25 ` Jarek Poplawski
2007-10-12 8:42 ` Helge Hafting
2007-10-12 9:12 ` Jarek Poplawski
2007-10-12 9:44 ` Nick Piggin
2007-10-12 10:04 ` Jarek Poplawski
2007-10-12 12:44 ` Helge Hafting
2007-10-12 13:29 ` Jarek Poplawski
2007-10-15 10:17 ` Helge Hafting
2007-10-15 11:53 ` Jarek Poplawski
2007-10-12 8:57 ` Nick Piggin
2007-10-12 9:55 ` Jarek Poplawski
2007-10-12 10:42 ` Nick Piggin
2007-10-12 11:55 ` Jarek Poplawski
2007-10-12 12:10 ` Jarek Poplawski
2007-10-12 15:13 ` Linus Torvalds
2007-10-15 7:44 ` Jarek Poplawski
2007-10-15 8:09 ` Nick Piggin
2007-10-15 9:10 ` Jarek Poplawski
2007-10-15 9:24 ` Jarek Poplawski
2007-10-16 0:50 ` Nick Piggin
2007-10-16 9:00 ` Jarek Poplawski
2007-10-16 9:14 ` david
2007-10-16 12:49 ` Jarek Poplawski
2007-10-15 14:38 ` David Schwartz
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