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
Ingo
Hi, Ingo:
Yes, the extra 9 usecs overhead for running two threads in the 2.6.24
kernel when there are total of 8 cores (2 quad opterons). What is the
total number of cores do you have? I do not have machines that have dual
quad Xeons here for direct comparisons. Thank you.
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