CoMD-CUDA
CoMD-CUDA copied to clipboard
Published
20 hours ago •
NVIDIA
NVIDIA
P100 answers are wrong about half of the time
Is this a bug in your CoMD implementation, in CUB or somewhere else?
Software
This repo with 3c4bc9f290b7bd9d13e192a9f5a2e1519ba394b0, cub-1.6.4, and GCC 4.8.5.
Hardware
GPU 0: Tesla P100-PCIE-16GB (UUID: GPU-448db3f5-6256-eafe-698a-aeaa0452c2ff)
GPU BIOS Version : 86.00.26.00.01
Current ECC Mode : Enabled
Current Persistence Mode: Enabled
Current Application Clock :
Graphics : 405 MHz
SM : 405 MHz
Memory : 715 MHz
Gpu Current Temperature : 27C
Current Cuda Version : 8.0, V8.0.44
Input
for n in `seq 1 100` ; do ./bin/CoMD-cuda-mpi -e -x $n -y $n -z $n 2>&1 | tee eam.n$n.log ; done
Output
As you can see below, in 98 tests, I get an answer accurate to 3 decimals 50 times, an answer accurate to less than 3 decimals 9 times, and the nonsensical answer of zero 39 times.
The OpenMP reference implementation is accurate to at least three decimals for every one of these cases.
$ grep "Final energy" *log
eam.n100.log: Final energy : 0.000000000000
eam.n10.log: Final energy : 0.000000000000
eam.n11.log: Final energy : 0.000000000000
eam.n12.log: Final energy : 0.000000000000
eam.n13.log: Final energy : -3.335415333810
eam.n14.log: Final energy : -3.344402073878
eam.n15.log: Final energy : -3.352183853550
eam.n16.log: Final energy : -3.358988391471
eam.n17.log: Final energy : -3.364988589356
eam.n18.log: Final energy : -3.370319963769
eam.n19.log: Final energy : -3.375087496409
eam.n20.log: Final energy : -3.379376467145
eam.n21.log: Final energy : -3.383255004237
eam.n22.log: Final energy : -3.460504275628
eam.n23.log: Final energy : -3.460507369744
eam.n24.log: Final energy : -3.460505932912
eam.n25.log: Final energy : -3.460505614897
eam.n26.log: Final energy : -3.460507156488
eam.n27.log: Final energy : -3.460510956982
eam.n28.log: Final energy : -3.460511109727
eam.n29.log: Final energy : -3.460509116211
eam.n30.log: Final energy : -3.460509949100
eam.n31.log: Final energy : -3.460512404440
eam.n32.log: Final energy : -3.460517333917
eam.n33.log: Final energy : -3.460516969976
eam.n34.log: Final energy : -3.460523260102
eam.n35.log: Final energy : -3.460530043886
eam.n36.log: Final energy : -3.460530080663
eam.n37.log: Final energy : -3.460530076386
eam.n38.log: Final energy : -3.460530062114
eam.n39.log: Final energy : -3.460530062445
eam.n3.log: Final energy : 0.000000000000
eam.n40.log: Final energy : -3.460530026084
eam.n41.log: Final energy : -3.460530020319
eam.n42.log: Final energy : -3.460529998146
eam.n43.log: Final energy : -3.460530080067
eam.n44.log: Final energy : -3.460530017362
eam.n45.log: Final energy : -3.460530059833
eam.n46.log: Final energy : -3.460530050431
eam.n47.log: Final energy : -3.460530048647
eam.n48.log: Final energy : -3.460530052178
eam.n49.log: Final energy : -3.460530040624
eam.n4.log: Final energy : 0.000000000000
eam.n50.log: Final energy : -3.460530065898
eam.n51.log: Final energy : -3.460530046749
eam.n52.log: Final energy : 0.000000000000
eam.n53.log: Final energy : 0.000000000000
eam.n54.log: Final energy : 0.000000000000
eam.n55.log: Final energy : 0.000000000000
eam.n56.log: Final energy : 0.000000000000
eam.n57.log: Final energy : 0.000000000000
eam.n58.log: Final energy : 0.000000000000
eam.n59.log: Final energy : 0.000000000000
eam.n5.log: Final energy : 0.000000000000
eam.n60.log: Final energy : 0.000000000000
eam.n61.log: Final energy : 0.000000000000
eam.n62.log: Final energy : 0.000000000000
eam.n63.log: Final energy : 0.000000000000
eam.n64.log: Final energy : -3.460530071940
eam.n65.log: Final energy : -3.460530055180
eam.n66.log: Final energy : -3.460530078149
eam.n67.log: Final energy : -3.460530055283
eam.n68.log: Final energy : -3.460530090024
eam.n69.log: Final energy : -3.460530039012
eam.n6.log: Final energy : 0.000000000000
eam.n70.log: Final energy : -3.460530030326
eam.n71.log: Final energy : -3.460530063041
eam.n72.log: Final energy : -3.460530049675
eam.n73.log: Final energy : 0.000000000000
eam.n74.log: Final energy : 0.000000000000
eam.n75.log: Final energy : 0.000000000000
eam.n76.log: Final energy : 0.000000000000
eam.n77.log: Final energy : 0.000000000000
eam.n78.log: Final energy : 0.000000000000
eam.n79.log: Final energy : 0.000000000000
eam.n7.log: Final energy : 0.000000000000
eam.n80.log: Final energy : -3.460530042402
eam.n81.log: Final energy : -3.460530075259
eam.n82.log: Final energy : -3.460530037493
eam.n83.log: Final energy : -3.460530047495
eam.n84.log: Final energy : -3.460530042484
eam.n85.log: Final energy : -3.460530063053
eam.n86.log: Final energy : 0.000000000000
eam.n87.log: Final energy : 0.000000000000
eam.n88.log: Final energy : 0.000000000000
eam.n89.log: Final energy : 0.000000000000
eam.n8.log: Final energy : 0.000000000000
eam.n90.log: Final energy : 0.000000000000
eam.n91.log: Final energy : 0.000000000000
eam.n92.log: Final energy : -3.460530059056
eam.n93.log: Final energy : -3.460530073254
eam.n94.log: Final energy : -3.460530062317
eam.n95.log: Final energy : -3.460530042136
eam.n96.log: Final energy : -3.460530044903
eam.n97.log: Final energy : 0.000000000000
eam.n98.log: Final energy : 0.000000000000
eam.n99.log: Final energy : 0.000000000000
eam.n9.log: Final energy : 0.000000000000
I should add that the performance for the incorrect case indicates that no work as done.
$ grep "Average atom rate" *log
eam.n100.log: Average atom rate: 1101.19 atoms/us
eam.n10.log: Average atom rate: 9.67 atoms/us
eam.n11.log: Average atom rate: 12.76 atoms/us
eam.n12.log: Average atom rate: 16.66 atoms/us
eam.n13.log: Average atom rate: 6.45 atoms/us
eam.n14.log: Average atom rate: 8.96 atoms/us
eam.n15.log: Average atom rate: 10.65 atoms/us
eam.n16.log: Average atom rate: 12.16 atoms/us
eam.n17.log: Average atom rate: 14.24 atoms/us
eam.n18.log: Average atom rate: 15.79 atoms/us
eam.n19.log: Average atom rate: 18.23 atoms/us
eam.n20.log: Average atom rate: 21.12 atoms/us
eam.n21.log: Average atom rate: 22.33 atoms/us
eam.n22.log: Average atom rate: 19.49 atoms/us
eam.n23.log: Average atom rate: 21.67 atoms/us
eam.n24.log: Average atom rate: 22.08 atoms/us
eam.n25.log: Average atom rate: 23.82 atoms/us
eam.n26.log: Average atom rate: 25.63 atoms/us
eam.n27.log: Average atom rate: 21.70 atoms/us
eam.n28.log: Average atom rate: 23.77 atoms/us
eam.n29.log: Average atom rate: 26.88 atoms/us
eam.n30.log: Average atom rate: 26.29 atoms/us
eam.n31.log: Average atom rate: 28.70 atoms/us
eam.n32.log: Average atom rate: 30.57 atoms/us
eam.n33.log: Average atom rate: 27.77 atoms/us
eam.n34.log: Average atom rate: 28.53 atoms/us
eam.n35.log: Average atom rate: 30.45 atoms/us
eam.n36.log: Average atom rate: 30.46 atoms/us
eam.n37.log: Average atom rate: 32.72 atoms/us
eam.n38.log: Average atom rate: 32.69 atoms/us
eam.n39.log: Average atom rate: 31.88 atoms/us
eam.n3.log: Average atom rate: 0.23 atoms/us
eam.n40.log: Average atom rate: 33.18 atoms/us
eam.n41.log: Average atom rate: 35.16 atoms/us
eam.n42.log: Average atom rate: 32.59 atoms/us
eam.n43.log: Average atom rate: 34.55 atoms/us
eam.n44.log: Average atom rate: 37.20 atoms/us
eam.n45.log: Average atom rate: 34.56 atoms/us
eam.n46.log: Average atom rate: 36.10 atoms/us
eam.n47.log: Average atom rate: 36.49 atoms/us
eam.n48.log: Average atom rate: 34.53 atoms/us
eam.n49.log: Average atom rate: 35.86 atoms/us
eam.n4.log: Average atom rate: 0.61 atoms/us
eam.n50.log: Average atom rate: 38.54 atoms/us
eam.n51.log: Average atom rate: 36.93 atoms/us
eam.n52.log: Average atom rate: 606.72 atoms/us
eam.n53.log: Average atom rate: 616.94 atoms/us
eam.n54.log: Average atom rate: 650.27 atoms/us
eam.n55.log: Average atom rate: 661.82 atoms/us
eam.n56.log: Average atom rate: 675.76 atoms/us
eam.n57.log: Average atom rate: 703.17 atoms/us
eam.n58.log: Average atom rate: 718.96 atoms/us
eam.n59.log: Average atom rate: 726.88 atoms/us
eam.n5.log: Average atom rate: 1.23 atoms/us
eam.n60.log: Average atom rate: 759.02 atoms/us
eam.n61.log: Average atom rate: 768.25 atoms/us
eam.n62.log: Average atom rate: 779.04 atoms/us
eam.n63.log: Average atom rate: 810.19 atoms/us
eam.n64.log: Average atom rate: 39.69 atoms/us
eam.n65.log: Average atom rate: 39.83 atoms/us
eam.n66.log: Average atom rate: 38.91 atoms/us
eam.n67.log: Average atom rate: 39.79 atoms/us
eam.n68.log: Average atom rate: 38.71 atoms/us
eam.n69.log: Average atom rate: 37.90 atoms/us
eam.n6.log: Average atom rate: 2.04 atoms/us
eam.n70.log: Average atom rate: 38.68 atoms/us
eam.n71.log: Average atom rate: 39.54 atoms/us
eam.n72.log: Average atom rate: 38.71 atoms/us
eam.n73.log: Average atom rate: 933.20 atoms/us
eam.n74.log: Average atom rate: 927.36 atoms/us
eam.n75.log: Average atom rate: 953.39 atoms/us
eam.n76.log: Average atom rate: 945.81 atoms/us
eam.n77.log: Average atom rate: 956.08 atoms/us
eam.n78.log: Average atom rate: 976.78 atoms/us
eam.n79.log: Average atom rate: 979.80 atoms/us
eam.n7.log: Average atom rate: 3.19 atoms/us
eam.n80.log: Average atom rate: 40.51 atoms/us
eam.n81.log: Average atom rate: 39.83 atoms/us
eam.n82.log: Average atom rate: 39.65 atoms/us
eam.n83.log: Average atom rate: 40.58 atoms/us
eam.n84.log: Average atom rate: 39.82 atoms/us
eam.n85.log: Average atom rate: 39.84 atoms/us
eam.n86.log: Average atom rate: 1008.33 atoms/us
eam.n87.log: Average atom rate: 1031.48 atoms/us
eam.n88.log: Average atom rate: 1032.76 atoms/us
eam.n89.log: Average atom rate: 1031.55 atoms/us
eam.n8.log: Average atom rate: 4.96 atoms/us
eam.n90.log: Average atom rate: 1052.90 atoms/us
eam.n91.log: Average atom rate: 1039.54 atoms/us
eam.n92.log: Average atom rate: 39.44 atoms/us
eam.n93.log: Average atom rate: 39.30 atoms/us
eam.n94.log: Average atom rate: 40.35 atoms/us
eam.n95.log: Average atom rate: 40.24 atoms/us
eam.n96.log: Average atom rate: 39.66 atoms/us
eam.n97.log: Average atom rate: 1117.49 atoms/us
eam.n98.log: Average atom rate: 1098.96 atoms/us
eam.n99.log: Average atom rate: 1109.59 atoms/us
eam.n9.log: Average atom rate: 6.87 atoms/us