Messages in this thread |  | | From | Mark Hemment <> | Subject | Re: MMU & cache trick: page flips on COW? | Date | Tue, 14 Jan 1997 10:55:27 +0000 (GMT) |
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David S. Miller wrote: > If you truly want get around the no-write-allocate problem, do > something to the memcpy code itself which helps the situation. I > believe the memcpy etc. code in GNU libc written by Torbjourn > Granlund > does in fact do a quick read of the first word in each cache line > being copied to in order to work around this problem specifically, > and the speed increase does show up.
Yep, does offer a 'local' speed improve, at the expensive of filling half my L1 data cache! One page I don't need, and one page I _might_ need. But if someone wants to benchmark real-life suitations and prove my sceptism wrong...
csum_partial_copy() can use the same technique for increasing performance, but the hidden overhead probably outweights the benefits.
Regards,
markhe
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