From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brent Casavant Date: Wed, 26 Apr 2006 15:53:53 +0000 Subject: Re: I/O read, write implementation questions Message-Id: <20060426105259.L18889@chenjesu.americas.sgi.com> List-Id: References: <444E2EA6.8000604@bull.net> In-Reply-To: <444E2EA6.8000604@bull.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org 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