Re: Possible bug from kernel 2.6.22 and above, 2.6.24-rc4

Ingo Molnar wrote:

* Jie Chen <[email protected]> wrote:

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 ?

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

ok, i did that and rebuilt. I also did "make check" and got src/pthread_sync which i can run. The only thing i'm missing, if i run src/pthread_sync, it outputs "PARALLEL time":

 PARALLEL time =                           22.486103 microseconds +/- 3.944821
 PARALLEL overhead =                       10.638658 microseconds +/- 10.854154

not "BARRIER time". I've re-read the discussion and found no hint about how to build and run a barrier test. Either i missed it or it's so obvious to you that you didnt mention it :-)

	Ingo

Hi, Ingo:

Did you do configure --enable-public-release? My qmt is for qcd calculation (one type of physics code). Without the above flag one can only test PARALLEL overhead. Actually the PARALLEL benchmark has the same behavior as the BARRIER. Thanks.

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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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