Ingo Molnar wrote:
* Jie Chen <[EMAIL PROTECTED]> wrote:

I just disabled the affinity mask and reran the test. There were no significant changes for two threads (barrier overhead is around 9 microseconds). As for 8 threads, the barrier overhead actually drops a little, which is good. Let me know whether I can be any help. Thank you very much.

sorry to be dense, but could you give me instructions how i could remove the affinity mask and test the "barrier overhead" myself? I have built "pthread_sync" and it outputs numbers for me - which one would be the barrier overhead: Reference_time_1 ?

        Ingo
Hi, Ingo:

To disable affinity, do configure --enable-public-release --disable-thread_affinity. You should see barrier overhead like the following:
Computing BARRIER time

Sample_size  Average     Min    Max          S.D.        Outliers
 20      19.486162   19.482250   19.491400    0.002740      0

BARRIER time =        19.486162 microseconds +/- 0.005371
BARRIER overhead =    8.996257 microseconds +/- 0.006575

The Reference_time_1 is the elapsed time for single thread doing simple loop without any synchronization. Thank you.

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Jie Chen
Scientific Computing Group
Thomas Jefferson National Accelerator Facility
12000, Jefferson Ave.
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(757)269-5046 (office) (757)269-6248 (fax)
[EMAIL PROTECTED]
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