Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH 21/21]: powerpc/cell spidernet DMA coalescing | Date | Wed, 11 Oct 2006 11:25:09 +0200 |
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On Wednesday 11 October 2006 03:46, Geoff Levand wrote: > > > > The others look good, but this one complicates the code and doesn't have any benefit. 20 > > for 21 isn't bad. > > Is the motivation for this change to improve performance by reducing the overhead > of the mapping calls? If so, there may be some benefit for some systems. Could > you please elaborate? >
From what I understand, this patch drastically reduces the number of I/O PTEs that are needed in the iommu. With the current static IOMMU mapping, it should only make a difference during initialization, but any platform that uses a dynamic mapping of iommu entries will benefit a lot from it, because:
- the card can do better prefetching of consecutive memory - there are more I/O ptes available for other drivers.
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