Re: csum_partial_copy_fromuser patch, #2

David S. Miller (
Sun, 2 Feb 1997 15:26:27 -0500

From: (Alan Cox)
Date: Sun, 2 Feb 1997 17:10:33 +0000 (GMT)

Why not pass the address of a dummy long word. Thats even faster than
doing the check (assuming we only write on an error and errors are
rare anyway).

Jakub wants to have a single routine do it all, that is why. The
techniques we could do for long routines such as memset, and now the
checksum stuff especially, is to have just one routine which has all
the exception detection crap in it, but somehow to have the fault
exception fixup code know that "ahh, this was a non-foo_user
invocation, die_if_kernel()"

Yow! 11.26 MB/s remote host TCP bandwidth & ////
199 usec remote TCP latency over 100Mb/s ////
ethernet. Beat that! ////
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David S. Miller, /_____________/ / // /_/ ><