Talk:NAMD Benchmarks

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The efficiency of a parallel system describes the fraction of the time that is being used by the processors for a given computation. It is defined as

        Execution time using one processor       ts
E(n)= --------------------------------------  = ----
      N * Execution time using N processors     N tn

In general, parallel jobs should scale to at least 70% efficiency. The ASC's DMC recommends a scaling efficiency of 75% or greater. For NAMD the efficiency of a parallel job can be calculated as follows (where N is processors committed to the job):

  days/ns where N = 1
 --------------------- * 100 = Efficiency
      N * days/ns


Information on NAMD performance Scaling is available at: http://www.ks.uiuc.edu/Research/namd/wiki/?NamdPerformanceTuning

Benchmark used for performance evaluation on the Cheaha, Biowulf, and DMC is Apoa1 from the NAMD suite and is available at: http://www.ks.uiuc.edu/Research/namd/utilities/

The parameters for the benchmark used through out are: 500 steps, 92K atoms, 12A cutoff + PME every 4 steps.


Sample Benchmark using NAMD

Sample Benchmark comparing Days/ns for Cheaha, Biowulf, and DMC using InfiniBand

Days/ns (efficiency) on Cheaha, Biowulf, and DMC
Processors Cheaha Biowulf DMC <ref group="note" >No hardware control was possible for the ASC's DMC and as such it is possible that different runs might have run on different hardware. *Efficiency on DMC using 4 processors is above 100%. This could be probably because of an older generation processor being used to run the job serially i.e. using 1 processor, thus setting a lower baseline to begin with causing the efficiency to go up as better processors are available for the parallel jobs.</ref>
1 15.4054 (100%) 18.0535 (100%) 19.1000 (100%)
2 7.7119 (99.87%) 9.5163 (94.86%) 9.7600 (97.84%)
4 3.8933 (98.92%) 4.9222 (91.69%) 4.7570 (100.3%)*
8 1.9653 (97.98%) 2.5763 (87.59%) 2.5360 (94.14%)
16 0.9950 (96.76%) 1.2658 (89.14%) 1.3870 (86.06%)
32 0.5101 (94.37%) 0.6463 (87.29%) 0.7438 (80.24%)
64 0.2592 (92.83%) 0.3390 (83.22%) 0.3938 (75.78%)
128 0.1360 (88.45%) NA NA
256 0.0770 (78.09%) NA NA
512 0.0439 (68.49%) NA NA
NAMD benchmark img1 Days cheaha dmc biowulf.png
NAMD benchmark img2 Efficiency cheaha dmc biowulf.png


Bench mark notes

The above benchmarks were run using NAMD 2.8b1 and the Apoa1 benchmark suite from NAMD.

On Cheaha, only the third generation hardware was used for the above benchmarks. More information about the hardware used on Cheaha is available here.

The data for the NIH-Biowulf benchmarks is available at: http://biowulf.nih.gov/apps/namd/namd_bench.html. The Biowulf hardware used for comparison in the e2800 with Infiniband.

ASC-DMC

<references group="note"/>


Comparison of Ethernet and IB

Ethernet vs Infiniband interconnect on Cheaha Gen 3 hardware
Processors Infiniband Ethernet
1 15.4054 (100%) 15.4040 (100%)
2 7.7119 (99.87%) 7.7800 (98.99%)
4 3.8933 (98.92%) 3.9405 (97.72%)
8 1.9653 (97.98%) 2.2816 (84.39%)
16 0.9950 (96.76%) 1.2714 (75.74%)
32 0.5101 (94.37%) 0.6973 (69.03%)
64 0.2592 (92.83%) 0.6562 (36.67%)
128 0.1360 (88.45%) 0.8950 (13.44%)
256 0.0770 (78.09%) 0.8632 (6.97%)
512 0.0439 (68.49%) NA
NAMD benchmark img3 Ib eth days ns 2.8.png
NAMD benchmark img4 Ib eth efficiency 2.8.png

Comparison on different Generations of Cheaha hardware on NAMD with Infinband

Cheaha Gen 2 and Gen 3 hardware using NAMD 2.8 and Inifiband
Processors Generation 3 Generation 2
1 15.4054 (100%) 15.9300 (100%)
2 7.7119 (99.87%) 8.6620 (91.98%)
4 3.8933 (98.92%) 4.2560 (93.59%)
8 1.9653 (97.98%) 2.3450 (84.93%)
16 0.9950 (96.76%) 1.2060 (82.56%)
32 0.5101 (94.37%) 0.6420 (77.57%)
64 0.2592 (92.83%) 0.2750 (90.38%)
128 0.1360 (88.45%) 0.1620 (76.81%)
256 0.0770 (78.09%) NA
512 0.0439 (68.49%) NA
NAMD benchmark img5 Days gen2 gen3 infiniband.png
NAMD benchmark img6 Efficiency gen2 gen3 ib.png

Hardware Notes

Generation 3 hardware contains 576 cores. 2.66 GHz Intel Xeon Hex-core (48-2x6 core) Generation 2 hardware contains 192 cores. 3.06 GHz Intel Xeon Quad-core (24-2x4 core) More information about the hardware used on Cheaha is available here.

Actual job benchmarks (Segrest job)

Speedup (Actual Wall times and CPU times)

Actual job comparison to IBM BG/L

Perform Your Own Benchmarks