Please replace the very slow Mac OS X pthread_mutex locks with the WTF::Lock implementation to benefit all applications. I can live with it still being 64 bytes and the scheduling being not completely fair. The OS X pthread mutexes are several times slower than Linux on the same hardware.
Which OS X Release? with which benchmark? uncontended pthread_mutex was made significantly faster in OS X El Capitan (almost twice as fast as before), and on my own mac is only twice as slow as OSSpinLock, and OSSpinLock unlock is a store(lock, 0), where a mutex usually need an xchg or cmpxchg which amount for most of the 2x performance loss.
I very very much doubt that linux implementation is that different (I'm actually fairly confident pthread_mutex on linux and OS X El Capitan+ are mostly on par)
