Re: Kernel checksum routime (>=5)x86 optimization

Jamie Lokier (lkd@tantalophile.demon.co.uk)
Tue, 18 May 1999 07:22:24 +0200


Kurt Garloff wrote:
> Well, I hacked a test. It seems my theory fails. Can someone explain, why
> the PPro does not perform better using two regs?

Because each instruction still depends on the previous one:
`adcl' means to use the carry flag from the previous instruction.

For instructions this simple the integer units are probably faster than
the instruction decoder anyway.

You might get better results with the PIII's 128-bit SIMD instructions ;-)

-- Jamie

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