On Sun, Sep 15, 2013 at 8:13 AM, Kevin <k...@gatorgraphics.com> wrote: > My attempts to compile it vectorized on OS X seemed to have failed since I > don't find a vector instruction in the .o file even though the options > -msse4.1 -funroll-loops -ftree-vectorize should be supported according to the > man page for Apple's llvm-gcc.
I'm not sure what version of LLVM Apple is using for llvm-gcc. I know that clang+llvm 3.3 can successfully vectorize the checksum algorithm when -O3 is used. > So, has anyone compiled checksum vectorized on OS X? Are there any > performance data that would indicate whether or not I should worry with this > in the first place? Even without vectorization the worst case performance hit is about 20%. This is for a workload that is fully bottlenecked on swapping pages in between shared buffers and OS cache. In real world cases it's hard to imagine it having any measurable effect. A single core can checksum several gigabytes per second of I/O without vectorization, and about 30GB/s with vectorization. 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 (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
