[chibi@centos7 nbody]$ ./nbody -benchmark -numbodies=256000 -numdevices=4
Run "nbody -benchmark [-numbodies=<numBodies>]" to measure performance.
        -fullscreen       (run n-body simulation in fullscreen mode)
        -fp64             (use double precision floating point values for simulation)
        -hostmem          (stores simulation data in host memory)
        -benchmark        (run benchmark to measure performance)
        -numbodies=<N>    (number of bodies (>= 1) to run in simulation)
        -device=<d>       (where d=0,1,2.... for the CUDA device to use)
        -numdevices=<i>   (where i=(number of CUDA devices > 0) to use for simulation)
        -compare          (compares simulation results running once on the default GPU and once on the CPU)
        -cpu              (run n-body simulation on the CPU)
        -tipsy=<file.bin> (load a tipsy model file for simulation)

NOTE: The CUDA Samples are not meant for performance measurements. Results may vary when GPU Boost is enabled.

number of CUDA devices  = 4
> Windowed mode
> Simulation data stored in system memory
> Single precision floating point simulation
> 4 Devices used for simulation
GPU Device 0: "GeForce GTX 1070" with compute capability 6.1

> Compute 6.1 CUDA device: [GeForce GTX 1070]
> Compute 6.1 CUDA device: [GeForce GTX 1050 Ti]
> Compute 6.1 CUDA device: [GeForce GTX 1070]
> Compute 6.1 CUDA device: [GeForce GTX 1070]
number of bodies = 256000
256000 bodies, total time for 10 iterations: 1113.316 ms
= 588.656 billion interactions per second
= 11773.113 single-precision GFLOP/s at 20 flops per interaction
[chibi@centos7 nbody]$ nvidia-smi
Sat Jul  8 10:41:44 2017
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 381.22                 Driver Version: 381.22                    |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|===============================+======================+======================|
|   0  GeForce GTX 105...  Off  | 0000:01:00.0      On |                  N/A |
| 35%   38C    P8    35W /  75W |    169MiB /  4038MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+
|   1  GeForce GTX 1070    Off  | 0000:02:00.0     Off |                  N/A |
|  0%   43C    P8     6W / 195W |      2MiB /  8114MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+
|   2  GeForce GTX 1070    Off  | 0000:82:00.0     Off |                  N/A |
|  0%   47C    P8     7W / 151W |      2MiB /  8114MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+
|   3  GeForce GTX 1070    Off  | 0000:83:00.0     Off |                  N/A |
|  8%   50C    P8     7W / 151W |      2MiB /  8114MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+

+-----------------------------------------------------------------------------+
| Processes:                                                       GPU Memory |
|  GPU       PID  Type  Process name                               Usage      |
|=============================================================================|
|    0      1548    G   /usr/bin/Xorg                                   95MiB |
|    0      3462    G   /usr/bin/gnome-shell                            71MiB |
+-----------------------------------------------------------------------------+
[chibi@centos7 nbody]$ nvidia-smi
Sat Jul  8 10:43:40 2017
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 381.22                 Driver Version: 381.22                    |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|===============================+======================+======================|
|   0  GeForce GTX 105...  Off  | 0000:01:00.0      On |                  N/A |
| 35%   38C    P8    35W /  75W |    169MiB /  4038MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+
|   1  GeForce GTX 1070    Off  | 0000:02:00.0     Off |                  N/A |
|  0%   42C    P8     6W / 195W |      2MiB /  8114MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+
|   2  GeForce GTX 1070    Off  | 0000:82:00.0     Off |                  N/A |
|  0%   46C    P8     7W / 151W |      2MiB /  8114MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+
|   3  GeForce GTX 1070    Off  | 0000:83:00.0     Off |                  N/A |
|  4%   49C    P8     7W / 151W |      2MiB /  8114MiB |      0%      Default |
+-------------------------------+----------------------+----------------------+

+-----------------------------------------------------------------------------+
| Processes:                                                       GPU Memory |
|  GPU       PID  Type  Process name                               Usage      |
|=============================================================================|
|    0      1548    G   /usr/bin/Xorg                                   95MiB |
|    0      3462    G   /usr/bin/gnome-shell                            72MiB |
+-----------------------------------------------------------------------------+
[chibi@centos7 nbody]$