On Tue, Sep 14, 2004 at 01:13:29PM +0200, Arjan van de Ven wrote:

On Tue, Sep 14, 2004 at 06:34:07AM -0300, Marcelo Tosatti wrote:

quoted

How come short access can cost 1 extra cycle? Because you need two "read bytes" ?

on an x86, a word (2byte) access will cause a prefix byte to the
instruction, that particular prefix byte will take an extra cycle during execution
of the instruction and potentially reduces the parallal decodability of
instructions....

OK thanks Arjan, where did you read this? The "Intel IA32 Optimization Guide" ?

Thanks for the info.

Andrew, we might want to revert the pagevec shrinkage part which changes couple
of variables to short - want to keep the "15" though.


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