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From: akepner@sgi.com
Date: Wed, 5 Mar 2008 10:13:07 -0800
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Grant Grundler <grundler@parisc-linux.org>,
       Michael Ellerman <michael@ellerman.id.au>,
       Tony Luck <tony.luck@intel.com>,
       Jesse Barnes <jbarnes@virtuousgeek.org>, Jes Sorensen <jes@sgi.com>,
       Randy Dunlap <randy.dunlap@oracle.com>,
       Roland Dreier <rdreier@cisco.com>, David Miller <davem@davemloft.net>,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3 v3] dma: document dma_{un}map_{single|sg}_attrs() interface
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On Fri, Feb 29, 2008 at 12:37:56PM -0600, James Bottomley wrote:
> ....
> To be honest, I still don't like the name.  SYNC_ON_WRITE is the SN2
> implementation.  What it's actually doing is implementing strict
> ordering semantics.  I think it should really be
> DMA_ATTR_STRICT_ORDERING (with a corresponding
> DMA_ATTR_RELAXED_ORDERING)....

I've been thinking about a new name, but don't like 
DMA_ATTR_STRICT_ORDERING. 

What I'm trying to do is to establish order (across 
a NUMA fabric) of DMA to different memory regions, i.e., 
DMA to memory region A forces all outstanding DMA (to 
memory regions B, C,....) to complete first.

DMA_ATTR_STRICT_ORDERING sounds like a PCI thing to me, 
and this is a NUMA interconnect thing.

-- 
Arthur