On Tue, Sep 23, 2014 at 8:15 PM, Florian Weimer <f...@deneb.enyo.de> wrote: > * Ants Aasma: > >> CRC has exactly one hardware implementation in general purpose CPU's > > I'm pretty sure that's not true. Many general purpose CPUs have CRC > circuity, and there must be some which also expose them as > instructions.
I must eat my words here, indeed AMD processors starting from Bulldozer do implement the CRC32 instruction. However, according to Agner Fog, AMD's implementation has a 6 cycle latency and more importantly a throughput of 1/6 per cycle. While Intel's implementation on all CPUs except the new Atom has 3 cycle latency and 1 instruction/cycle throughput. This means that there still is a significant handicap for AMD platforms, not to mention Power or Sparc with no hardware support. Some ARM's implement CRC32, but I haven't researched what their performance is. Regards, Ants Aasma -- Cybertec Schönig & Schönig GmbH Gröhrmühlgasse 26 A-2700 Wiener Neustadt Web: http://www.postgresql-support.de -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers