Re: Possible bug from kernel 2.6.22 and above, 2.6.24-rc4
From: Jie Chen
Date: Wed Dec 05 2007 - 17:16:57 EST
Ingo Molnar wrote:
* Jie Chen <chen@xxxxxxxx> 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.
###############################################
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)
chen@xxxxxxxx
###############################################
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