Messages in this thread |  | | Date | Sat, 03 Jun 2006 17:48:52 -0700 | | From | "H. Peter Anvin" <> | | Subject | Re: memcpy_toio on i386 using byte writes even when n%2==0 |
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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.
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