[petsc-users] log_summary time ratio and flops ratio

Xiangdong epscodes at gmail.com
Fri Feb 5 11:12:03 CST 2016


Hello everyone,

When I looked at the log_summary, I found that flops ratio of VecDot is
1.1, but the time ratio is 1.8. Also the flops ratio of MatMult is 1.2, but
the time ratio is 1.6. I am using the simple SOR preconditioner on 256
procs. Since each of them consumes about 20% of total time, is it worth
looking into these imbalance issue? If yes, how do I know which procs are
causing the issue? What tools should I start with?

Thanks.

Xiangdong

------------------------------------------------------------------------------------------------------------------------
Event                Count      Time (sec)     Flops
      --- Global ---  --- Stage ---   Total
                   Max Ratio  Max     Ratio   Max  Ratio  Mess   Avg len
Reduct  %T %F %M %L %R  %T %F %M %L %R Mflop/s
------------------------------------------------------------------------------------------------------------------------

--- Event Stage 0: Main Stage

VecView               44 1.0 3.9026e+00 1.0 0.00e+00 0.0 0.0e+00 0.0e+00
4.8e+01  1  0  0  0  0   1  0  0  0  0     0
VecDot            817452 1.0 1.5972e+02 1.8 1.51e+10 1.1 0.0e+00 0.0e+00
8.2e+05 18  3  0  0 40  18  3  0  0 40 22969
VecMDot           613089 1.0 5.8918e+01 1.1 2.27e+10 1.1 0.0e+00 0.0e+00
6.1e+05  8  4  0  0 30   8  4  0  0 30 93397
VecNorm           618619 1.0 1.4426e+02 2.2 1.14e+10 1.1 0.0e+00 0.0e+00
6.2e+05 15  2  0  0 30  15  2  0  0 30 19145
VecScale             938 1.0 8.3907e-03 1.2 8.67e+06 1.1 0.0e+00 0.0e+00
0.0e+00  0  0  0  0  0   0  0  0  0  0 250859
VecCopy             8159 1.0 1.0394e-01 1.6 0.00e+00 0.0 0.0e+00 0.0e+00
0.0e+00  0  0  0  0  0   0  0  0  0  0     0
VecSet              1884 1.0 3.9701e-02 2.1 0.00e+00 0.0 0.0e+00 0.0e+00
0.0e+00  0  0  0  0  0   0  0  0  0  0     0
VecAXPY          1021815 1.0 2.2148e+01 2.1 1.89e+10 1.1 0.0e+00 0.0e+00
0.0e+00  2  4  0  0  0   2  4  0  0  0 207057
VecAYPX           613089 1.0 6.5360e+00 1.9 1.13e+10 1.1 0.0e+00 0.0e+00
0.0e+00  1  2  0  0  0   1  2  0  0  0 420336
VecAXPBYCZ           191 1.0 3.7365e-03 1.4 7.06e+06 1.1 0.0e+00 0.0e+00
0.0e+00  0  0  0  0  0   0  0  0  0  0 458830
VecWAXPY             938 1.0 3.8502e-02 1.4 8.67e+06 1.1 0.0e+00 0.0e+00
0.0e+00  0  0  0  0  0   0  0  0  0  0 54669
VecMAXPY          613089 1.0 1.3276e+01 2.2 2.27e+10 1.1 0.0e+00 0.0e+00
0.0e+00  1  4  0  0  0   1  4  0  0  0 414499
VecLoad                5 1.0 2.0913e-01 1.0 0.00e+00 0.0 0.0e+00 0.0e+00
0.0e+00  0  0  0  0  0   0  0  0  0  0     0
VecScatterBegin   820695 1.0 1.8959e+01 2.8 0.00e+00 0.0 1.1e+09 4.6e+03
0.0e+00  2  0100100  0   2  0100100  0     0
VecScatterEnd     820695 1.0 5.2002e+01 4.2 0.00e+00 0.0 0.0e+00 0.0e+00
0.0e+00  4  0  0  0  0   4  0  0  0  0     0
VecReduceArith      2814 1.0 1.8517e-02 1.2 5.20e+07 1.1 0.0e+00 0.0e+00
0.0e+00  0  0  0  0  0   0  0  0  0  0 681995
VecReduceComm        938 1.0 2.6041e+00 3.4 0.00e+00 0.0 0.0e+00 0.0e+00
9.4e+02  0  0  0  0  0   0  0  0  0  0     0
MatMult           817452 1.0 1.9379e+02 1.6 2.04e+11 1.2 1.0e+09 4.6e+03
0.0e+00 23 40100100  0  23 40100100  0 253083
MatSOR            818390 1.0 1.9608e+02 1.5 2.00e+11 1.1 0.0e+00 0.0e+00
0.0e+00 22 40  0  0  0  22 40  0  0  0 247472
MatAssemblyBegin     939 1.0 7.9671e+00 6.0 0.00e+00 0.0 0.0e+00 0.0e+00
1.9e+03  1  0  0  0  0   1  0  0  0  0     0
MatAssemblyEnd       939 1.0 2.0570e-01 1.2 0.00e+00 0.0 2.6e+03 1.2e+03
8.0e+00  0  0  0  0  0   0  0  0  0  0     0
MatZeroEntries       938 1.0 1.8202e-01 2.0 0.00e+00 0.0 0.0e+00 0.0e+00
0.0e+00  0  0  0  0  0   0  0  0  0  0     0
SNESSolve            210 1.0 6.8585e+02 1.0 5.06e+11 1.2 1.1e+09 4.6e+03
2.1e+06 98100100100100  98100100100100 178411
SNESFunctionEval    2296 1.0 2.0512e+01 1.3 0.00e+00 0.0 2.9e+06 3.5e+03
0.0e+00  3  0  0  0  0   3  0  0  0  0     0
SNESJacobianEval     938 1.0 2.7680e+01 1.0 0.00e+00 0.0 1.2e+06 3.5e+03
1.9e+03  4  0  0  0  0   4  0  0  0  0     0
SNESLineSearch       938 1.0 9.2491e+00 1.0 6.07e+07 1.1 1.2e+06 3.5e+03
9.4e+02  1  0  0  0  0   1  0  0  0  0  1593
KSPSetUp             938 1.0 2.7661e-03 1.2 0.00e+00 0.0 0.0e+00 0.0e+00
2.0e+01  0  0  0  0  0   0  0  0  0  0     0
KSPSolve             938 1.0 6.3433e+02 1.0 5.06e+11 1.2 1.0e+09 4.6e+03
2.0e+06 91100100100 99  91100100100 99 192852
PCSetUp              938 1.0 2.1005e-04 3.1 0.00e+00 0.0 0.0e+00 0.0e+00
0.0e+00  0  0  0  0  0   0  0  0  0  0     0
PCApply           818390 1.0 1.9675e+02 1.5 2.00e+11 1.1 0.0e+00 0.0e+00
0.0e+00 22 40  0  0  0  22 40  0  0  0 246626
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