I assume you need other people to answer as well, but here is what I get:
$ sysctl -a | grep ^hw
hw.ncpu: 4
hw.byteorder: 1234
hw.memsize: 8589934592
hw.activecpu: 4
hw.physicalcpu: 4
hw.physicalcpu_max: 4
hw.logicalcpu: 4
hw.logicalcpu_max: 4
hw.cputype: 7
hw.cpusubtype: 8
hw.cpu64bit_capable: 1
It looks like our Mac OS X backend doesn't properly handle processors
that support hyperthreading without actually having hyperthreads enabled
in hardware. Your processor has 4-core without HT but it's based on a
processor with up to 8 cores and 16 threads. Our current code uses the
latter and
