On Mon, 2013-04-22 at 19:25 +0300, Ants Aasma wrote:
> I was just now writing up a generic C based patch based on the
> parallel FNV-1a + shift that we discussed with Florian with an added
> round of mixing. Testing the performance in isolation indicates that:
> 1) it is about an order of magnitude faster than the Sarwate CRC
> method used in Postgresql.
> 2) it is about 2x faster than fastest software based CRC method.
> 3) by using -msse4.1 -funroll-loops -ftree-vectorize compilation
> options the performance improves 5x. (within 20% of handcoded ASM)

That's great news!

This means that we can have a simple C implementation in a separate
file, and pass a few build flags when compiling just that file (so it
doesn't affect other code). That should make reviewers/committers happy
(including me).

FWIW, that was my last real concern about FNV (reviewability). I'm not
worried about the performance based on your analysis; nor am I worried
about the error detection rate.

        Jeff Davis

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