On Tue, 2007-12-11 at 17:11 -0500, Jie Chen wrote: > Ingo Molnar wrote: > > * Jie Chen <[EMAIL PROTECTED]> wrote: > > > >> The following is pthread_sync output for 2.6.21.7-cfs-v24 #1 SMP > >> kernel. > > > >> 2 threads: > > > >> PARALLEL time = 11.106580 microseconds +/- 0.002460 > >> PARALLEL overhead = 0.617590 microseconds +/- 0.003409 > > > >> Output for Kernel 2.6.24-rc4 #1 SMP > > > >> PARALLEL time = 19.668450 microseconds +/- 0.015782 > >> PARALLEL overhead = 9.157945 microseconds +/- 0.018217 > > > > ok, so the problem is that this PARALLEL time has an additional +9 usecs > > overhead, right? I dont see this myself on a Core2 CPU: > > > > PARALLEL time = 10.446933 microseconds +/- > > 0.078849 > > PARALLEL overhead = 0.751732 microseconds +/- 0.177446 > >
On my dual socket AMD Athlon MP 2.6.20-13-generic PARALLEL time = 22.751875 microseconds +/- 21.370942 PARALLEL overhead = 7.046595 microseconds +/- 24.370040 2.6.24-rc5 PARALLEL time = 17.365543 microseconds +/- 3.295133 PARALLEL overhead = 2.213722 microseconds +/- 4.797886
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