On Mon, Apr 22, 2013 at 10:57 PM, Ants Aasma <a...@cybertec.at> wrote: > On Mon, Apr 22, 2013 at 10:54 PM, Simon Riggs <si...@2ndquadrant.com> wrote: >> On 22 April 2013 20:32, Florian Pflug <f...@phlo.org> wrote: >> >>> Assuming that we only ship a plain C implementation with 9.3, what >>> are we missing on that front? The C implementation of FNV1+SHIFT is >>> only a few dozen lines or so. >> >> Forgive me, I can't seem to locate the patch for this? Re-post please, >> just for clarity. > > Not posted yet. I'm writing it as we speak. Will post within half an hour or > so.
A slight delay, but here it is. I didn't lift the checksum part into a separate file as I didn't have a great idea what I would call it. The code is reasonably compact so I don't see a great need for this right now. It would be more worth the effort when/if we add non-generic variants. I'm not particularly attached to the method I used to mask out pd_checksum field, this could be improved if someone has a better idea how to structure the code. I confirmed with objdump that compiling on GCC 4.7 with -msse4.1 -funroll-loops -ftree-vectorize does in fact vectorize that loop. Simple way to verify: objdump -d src/backend/storage/page/bufpage.o | grep pmulld | wc -l should output 16. Unfortunately I can't work on this patch for about a week. Postgresql 9.3 will have to wait for me as I need to tend to the release of Ants v2.0. Regards, Ants Aasma -- Cybertec Schönig & Schönig GmbH Gröhrmühlgasse 26 A-2700 Wiener Neustadt Web: http://www.postgresql-support.de
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