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From: Roland Dreier <rdreier@cisco.com>
To: Jes Sorensen <jes@sgi.com>
Cc: "Bryan O'Sullivan" <bos@pathscale.com>,
	Andrew Morton <akpm@osdl.org>, Andi Kleen <ak@suse.de>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Define wc_wmb, a write barrier for PCI write combining
Date: Tue, 28 Feb 2006 07:42:52 -0800	[thread overview]
Message-ID: <adar75nlcar.fsf@cisco.com> (raw)
In-Reply-To: <yq08xrvhkee.fsf@jaguar.mkp.net> (Jes Sorensen's message of "28 Feb 2006 05:01:29 -0500")

    Jes> Could you explain why the current mmiowb() API won't suffice
    Jes> for this?  It seems that this is basically trying to achieve
    Jes> the same thing.

I don't believe mmiowb() is at all the same thing.  mmiowb() is all
about ordering writes between _different_ CPUs without incurring the
cost of flushing posted writes by issuing a read on the bus.  wc_wmb()
would just act like a true wmb(), even when using write-combining
regions on x86 -- in other words, there would be no cross-CPU synchronization.

 - R.

  reply	other threads:[~2006-02-28 15:42 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-02-25  4:20 [PATCH] Define wc_wmb, a write barrier for PCI write combining Bryan O'Sullivan
2006-02-25  4:43 ` Andi Kleen
2006-02-25  7:34   ` Bryan O'Sullivan
2006-02-25 13:28     ` Andi Kleen
2006-02-25 17:20       ` Bryan O'Sullivan
2006-02-25 19:01       ` Bryan O'Sullivan
2006-02-28 17:44         ` Jesse Barnes
2006-02-28 17:50           ` Roland Dreier
2006-02-28 17:50           ` Jesse Barnes
2006-02-28 17:52           ` Bryan O'Sullivan
2006-02-28 17:59             ` Jesse Barnes
2006-02-25 14:28 ` Benjamin LaHaise
2006-02-25 17:11   ` Bryan O'Sullivan
2006-02-25 17:41     ` Benjamin LaHaise
2006-02-28 17:50       ` Bryan O'Sullivan
2006-02-28 17:58         ` Benjamin LaHaise
2006-02-28 18:20           ` Bryan O'Sullivan
2006-02-28 19:03             ` Benjamin LaHaise
2006-02-28 19:20               ` Bryan O'Sullivan
2006-02-28 19:33                 ` Andi Kleen
2006-02-28 19:44                   ` Bryan O'Sullivan
2006-03-01 19:20                   ` Bryan O'Sullivan
2006-03-01 19:27                     ` Andi Kleen
2006-03-01 19:43                       ` Bryan O'Sullivan
2006-03-01 19:49                         ` Andi Kleen
2006-03-01 20:05                           ` Bryan O'Sullivan
2006-03-01 20:26                             ` Benjamin LaHaise
2006-03-01 20:35                               ` Bryan O'Sullivan
2006-02-28 19:34                 ` Benjamin LaHaise
2006-02-28 18:22           ` Christopher Friesen
2006-02-28 10:01 ` Jes Sorensen
2006-02-28 15:42   ` Roland Dreier [this message]
2006-02-28 16:08     ` Jes Sorensen
2006-02-28 17:02       ` Roland Dreier
2006-02-28 17:13         ` Jesse Barnes
2006-02-28 17:20         ` Jes Sorensen
2006-03-01  8:16           ` Jeremy Higdon
2006-03-01  8:24           ` Jeremy Higdon
2006-02-28 17:11       ` Jesse Barnes
2006-02-28 17:57   ` Bryan O'Sullivan
2006-02-28 18:07     ` linux-os (Dick Johnson)
2006-02-28 18:24       ` Christopher Friesen
2006-03-01 10:45     ` Jes Sorensen
2006-03-01 17:04       ` Roland Dreier

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