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From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] mlx4_en: map entire pages to increase throughput
Date: Tue, 17 Jul 2012 05:50:05 -0700 (PDT)
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From: "David Laight" <David.Laight@ACULAB.COM>
Date: Tue, 17 Jul 2012 13:42:04 +0100

> Would there be any mileage in permanently allocating IOMMU
> virtual address to the ring entries, then 'just' assigning
> the correct physical address during rx/tx setup?

There is a not a one to one mapping between these two entities,
in particular on the transmit side.

A transmit packet can have multiple segments, some of which are
larger than one IOMMU page.