Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: memcpy_toio on i386 using byte writes even when n%2==0 | Date | Tue, 30 May 2006 18:13:27 -0700 (PDT) |
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Followup to: <447CE99B.7070707@shaw.ca> By author: Robert Hancock <hancockr@shaw.ca> In newsgroup: linux.dev.kernel > > > > Note that there isn't any code for moving dwords because the > > chances of gaining anything are slim (alignment may hurt). > > I'd say the chances of gaining something from executing half as many > instructions on copying a large block of memory are very good indeed.. >
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.
-hpa
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