From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Linus Torvalds <torvalds@osdl.org>
Cc: David Howells <dhowells@redhat.com>,
akpm@osdl.org, ak@suse.de, mingo@redhat.com, jblunck@suse.de,
bcrl@linux.intel.com, matthew@wil.cx, linux-arch@vger.kernel.org,
linuxppc64-dev@ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: Memory barriers and spin_unlock safety
Date: Tue, 07 Mar 2006 18:55:06 +0000 [thread overview]
Message-ID: <1141757706.31814.80.camel@localhost.localdomain> (raw)
In-Reply-To: <Pine.LNX.4.64.0603071024550.3573@g5.osdl.org>
On Maw, 2006-03-07 at 10:28 -0800, Linus Torvalds wrote:
> x86 tends to serialize PIO too much (I think at least Intel CPU's will
> actually wait for the PIO write to be acknowledged by _something_ on the
> bus, although it obviously can't wait for the device to have acted on it).
Don't bet on that 8(
In the PCI case the I/O write appears to be acked by the bridges used on
x86 when the write completes on the PCI bus and then back to the CPU.
MMIO is thankfully posted. At least thats how the timings on some
devices look.
next prev parent reply other threads:[~2006-03-07 18:50 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-03 16:03 Memory barriers and spin_unlock safety David Howells
2006-03-03 16:45 ` David Howells
2006-03-03 17:03 ` Linus Torvalds
2006-03-03 20:17 ` David Howells
2006-03-03 21:34 ` Linus Torvalds
2006-03-03 21:51 ` Benjamin LaHaise
2006-03-03 22:21 ` Linus Torvalds
2006-03-03 22:36 ` Linus Torvalds
2006-03-07 17:36 ` David Howells
2006-03-07 17:40 ` Matthew Wilcox
2006-03-07 17:56 ` Jesse Barnes
2006-03-07 18:18 ` Alan Cox
2006-03-07 18:28 ` Linus Torvalds
2006-03-07 18:55 ` Alan Cox [this message]
2006-03-07 20:21 ` Linus Torvalds
2006-03-03 20:02 ` Arjan van de Ven
2006-03-03 16:55 ` Linus Torvalds
2006-03-03 20:15 ` David Howells
2006-03-03 21:31 ` Linus Torvalds
2006-03-03 21:06 ` Benjamin Herrenschmidt
2006-03-03 21:18 ` Hollis Blanchard
2006-03-03 21:52 ` David S. Miller
2006-03-03 22:04 ` Linus Torvalds
2006-03-04 10:58 ` Paul Mackerras
2006-03-04 22:49 ` Benjamin Herrenschmidt
2006-03-04 10:58 ` Paul Mackerras
2006-03-04 17:28 ` Linus Torvalds
2006-03-08 3:20 ` Paul Mackerras
2006-03-08 3:54 ` Linus Torvalds
2006-03-08 13:12 ` Alan Cox
2006-03-08 15:30 ` Linus Torvalds
2006-03-05 2:04 ` Michael Buesch
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