From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>,
linux-ia64@vger.kernel.org, Jesse Barnes <jesse.barnes@intel.com>,
linuxppc-dev@ozlabs.org
Subject: Re: wmb vs mmiowb
Date: Thu, 23 Aug 2007 18:27:42 +0200 [thread overview]
Message-ID: <1187886462.5972.17.camel@localhost.localdomain> (raw)
In-Reply-To: <alpine.LFD.0.999.0708230915000.30176@woody.linux-foundation.org>
On Thu, 2007-08-23 at 09:16 -0700, Linus Torvalds wrote:
>
> On Thu, 23 Aug 2007, Nick Piggin wrote:
> >
> > Also, FWIW, there are some advantages of deferring the mmiowb thingy
> > until the point of unlock.
>
> And that is exactly what ppc64 does.
>
> But you're missing a big point: for 99.9% of all hardware, mmiowb() is a
> total no-op. So when you talk about "advantages", you're not talking about
> any *real* advantage, are you?
I wonder whether it might be worth removing mmiowb and having all archs
that matter do like ppc64 though... It's just yet another confusing
barrier that most driver writers get wrong..
Cheers,
Ben.
next prev parent reply other threads:[~2007-08-23 16:27 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-22 4:57 wmb vs mmiowb Nick Piggin
2007-08-22 18:07 ` Linus Torvalds
2007-08-22 19:02 ` Jesse Barnes
2007-08-23 2:20 ` Nick Piggin
2007-08-23 2:57 ` Linus Torvalds
2007-08-23 3:54 ` Nick Piggin
2007-08-23 16:14 ` Linus Torvalds
2007-08-23 4:20 ` Nick Piggin
2007-08-23 16:16 ` Linus Torvalds
2007-08-23 16:27 ` Benjamin Herrenschmidt [this message]
2007-08-24 3:09 ` Nick Piggin
2007-08-28 20:56 ` Brent Casavant
2007-08-29 0:59 ` Nick Piggin
2007-08-29 18:53 ` Brent Casavant
2007-08-30 3:36 ` Nick Piggin
2007-08-30 19:42 ` Brent Casavant
2007-09-03 20:48 ` Nick Piggin
2007-08-24 2:59 ` Nick Piggin
2007-08-23 17:02 ` Jesse Barnes
2007-08-23 1:59 ` Nick Piggin
2007-08-23 7:27 ` Benjamin Herrenschmidt
2007-08-23 16:56 ` Jesse Barnes
2007-08-24 3:12 ` Nick Piggin
2007-08-28 21:21 ` Brent Casavant
2007-08-28 23:01 ` Peter Chubb
2007-08-23 7:25 ` Benjamin Herrenschmidt
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