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SubjectRe: memcpy_toio on i386 using byte writes even when n%2==0
Robert Hancock wrote:
> H. Peter Anvin wrote:
>> For something that generates I/O transactions, it's imperative to
>> generate the smallest possible number of transactions. Furthermore,
>> smaller than dword transactions aren't burstable, except at the
>> beginning and end of a burst.
>
> Well, theoretically for writes they could be, if the memory region was
> prefetchable and the PCI chipset supported byte merge. It certainly
> isn't optimal however.
>

If so, then merging doesn't matter either way.

-hpa
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