From: Andi Kleen <ak@suse.de>
To: Dave Jones <davej@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [rfc][patch 2/3] x86: fix IO write barriers
Date: Thu, 4 Oct 2007 20:21:59 +0200 [thread overview]
Message-ID: <200710042021.59704.ak@suse.de> (raw)
In-Reply-To: <20071004181044.GA23300@redhat.com>
On Thursday 04 October 2007 20:10:44 Dave Jones wrote:
> On Thu, Oct 04, 2007 at 07:53:16PM +0200, Andi Kleen wrote:
> >
> > > 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".
> > >
> >
> > Do you know if it made a big performance difference?
>
> On the winchip, it was a huge win. I can't remember exact numbers,
> but pretty much every benchmark I threw at it at the time showed
> significant improvement.
Significant as in >10%?
> > But yes we should probably just remove this special case to make
> > maintenance easier.
>
> It's CONFIG_SMP anyway, which none of the winchips were.
It's not. And we need memory barriers even without SMP
when talking to device drivers. Only the smp_*b()s get noped
on UP.
-Andi
next prev parent reply other threads:[~2007-10-04 18:22 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
2007-10-04 17:53 ` Andi Kleen
2007-10-04 18:10 ` Dave Jones
2007-10-04 18:21 ` Andi Kleen [this message]
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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