FYI, Intel's Vtune support has confirmed that pthreads is the only threading package that Vtune supports. Linux pthreads are being mapped into Linux processes, which gives them very poor performance compared to QuickThreads or other threading packages that run WITHIN a process. The very purpose of threads is to offer concurrency in code execution WITHOUT the heavy overhead of a full processes. This is why high performance applications rarely use pthreads. Considering how increasingly important multi-threading is becoming ( after all the latest generation of Intel's own Pentium 4 has built in hyperthreading support), I am quite puzzled that Vtune only support pthreads.