From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Nick Piggin <npiggin@suse.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hugh@veritas.com>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [patch] i386: avoid expensive ppro ordering workaround for default 686 kernels
Date: Fri, 04 Jan 2008 07:20:43 +1100 [thread overview]
Message-ID: <1199391643.7291.15.camel@pasglop> (raw)
In-Reply-To: <20080103142330.111d4067@lxorguk.ukuu.org.uk>
On Thu, 2008-01-03 at 14:23 +0000, Alan Cox wrote:
> > Hmm, I don't understand what you mean. Obviously other busmasters aren't
> > participating in any locking or smp_*mb() ordering protocols.
>
> The unlock paths are visible to busmasters
>
> write to DMA buffer
> unlock
> can turn into
>
> unlock
> write to DMA buffer
>
> Whether that actually matters in any code we have I don't know.
It matters with writes to MMIO at least, I don't know if your PPro bug
can cause that to be re-ordered tho.
Ben.
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next prev parent reply other threads:[~2008-01-03 20:20 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-18 1:26 [patch] mm: fix PageUptodate memory ordering bug Nick Piggin
2007-12-22 8:57 ` Andrew Morton
2007-12-22 12:14 ` Hugh Dickins
2007-12-23 6:54 ` Nick Piggin
2007-12-23 6:54 ` Nick Piggin
2007-12-23 5:57 ` Nick Piggin
2007-12-23 6:32 ` Andrew Morton
2007-12-23 7:15 ` Nick Piggin
2007-12-23 7:29 ` Andrew Morton
2007-12-23 9:14 ` Nick Piggin
2007-12-23 9:28 ` Andrew Morton
2007-12-23 16:02 ` Andi Kleen
2007-12-30 16:33 ` Ingo Molnar
2008-01-01 23:26 ` Nick Piggin
2008-01-02 21:01 ` Andi Kleen
2008-01-03 3:32 ` Nick Piggin
2008-01-03 13:08 ` Andi Kleen
2007-12-23 17:22 ` Linus Torvalds
2007-12-23 21:35 ` Nick Piggin
2007-12-23 22:41 ` Nick Piggin
2008-01-01 23:41 ` Alan Cox
2008-01-02 11:02 ` [patch] i386: avoid expensive ppro ordering workaround for default 686 kernels Nick Piggin
2008-01-02 13:44 ` Alan Cox
2008-01-03 4:17 ` Nick Piggin
2008-01-03 14:23 ` Alan Cox
2008-01-03 20:20 ` Benjamin Herrenschmidt [this message]
2008-01-03 22:23 ` Alan Cox
2008-01-03 23:10 ` Nick Piggin
2008-01-04 16:27 ` Alan Cox
2008-01-07 0:12 ` Nick Piggin
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