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.
Newport News, VA 23606
(757)269-5046 (office) (757)269-6248 (fax)
[email protected]
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