From: Brent Casavant <bcasavan@sgi.com>
To: linux-ia64@vger.kernel.org
Subject: Re: I/O read, write implementation questions
Date: Wed, 26 Apr 2006 15:53:53 +0000 [thread overview]
Message-ID: <20060426105259.L18889@chenjesu.americas.sgi.com> (raw)
In-Reply-To: <444E2EA6.8000604@bull.net>
On Wed, 26 Apr 2006, Brent Casavant wrote:
> Note that wmb() is not sufficient for writes, at least on SGI Altix.
> wmb() ensures that the write has issued from the processor, however
> it does not ensure that the I/O device itself has seen the write.
> The mmiowb() is the appropriate call to ensure that the write has
> been seen.
Oh, and lest I confuse anyone, wmb() is sufficient for writes to RAM.
It's only I/O writes for which it is insufficient.
Brent
--
Brent Casavant All music is folk music. I ain't
bcasavan@sgi.com never heard a horse sing a song.
Silicon Graphics, Inc. -- Louis Armstrong
prev parent reply other threads:[~2006-04-26 15:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-25 14:13 I/O read, write implementation questions Zoltan Menyhart
2006-04-25 14:46 ` David Mosberger-Tang
2006-04-25 15:20 ` Zoltan Menyhart
2006-04-25 23:20 ` Grant Grundler
2006-04-26 15:48 ` Brent Casavant
2006-04-26 15:53 ` Brent Casavant [this message]
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