Question

硬件：2张780Ti卡，软件： Ubuntu 14.01 LTS NVIDIA UNIX x86_64内核模块352.79 Wed Jan 13 16:17:53 PST 2016 GCC版本：gcc版本4.8.4（Ubuntu 4.8.4-2ubuntu1~14.04.1） CUDA 7.5

nvidia-smi表示

+------------------------------------------------------+                       
| NVIDIA-SMI 352.79     Driver Version: 352.79         |                       
|-------------------------------+----------------------+----------------------+
| 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 780 Ti  Off  | 0000:01:00.0     N/A |                  N/A |
| 30%   43C    P2    N/A /  N/A |    877MiB /  3071MiB |     N/A      Default |
+-------------------------------+----------------------+----------------------+
|   1  GeForce GTX 780 Ti  Off  | 0000:03:00.0     N/A |                  N/A |
| 29%   25C    P8    N/A /  N/A |     11MiB /  3071MiB |     N/A      Default |
+-------------------------------+----------------------+----------------------+

deviceQuery显示

CUDA Device Query (Runtime API) version (CUDART static linking)

Detected 1 CUDA Capable device(s)

Device 0: "GeForce GTX 780 Ti"
  CUDA Driver Version / Runtime Version          7.5 / 7.5
  CUDA Capability Major/Minor version number:    3.5
  Total amount of global memory:                 3072 MBytes (3221028864 bytes)
  (15) Multiprocessors, (192) CUDA Cores/MP:     2880 CUDA Cores
  GPU Max Clock rate:                            1084 MHz (1.08 GHz)
  Memory Clock rate:                             3500 Mhz
  Memory Bus Width:                              384-bit
  L2 Cache Size:                                 1572864 bytes
  Maximum Texture Dimension Size (x,y,z)         1D=(65536), 2D=(65536, 65536), 3D=(4096, 4096, 4096)
  Maximum Layered 1D Texture Size, (num) layers  1D=(16384), 2048 layers
  Maximum Layered 2D Texture Size, (num) layers  2D=(16384, 16384), 2048 layers
  Total amount of constant memory:               65536 bytes
  Total amount of shared memory per block:       49152 bytes
  Total number of registers available per block: 65536
  Warp size:                                     32
  Maximum number of threads per multiprocessor:  2048
  Maximum number of threads per block:           1024
  Max dimension size of a thread block (x,y,z): (1024, 1024, 64)
  Max dimension size of a grid size    (x,y,z): (2147483647, 65535, 65535)
  Maximum memory pitch:                          2147483647 bytes
  Texture alignment:                             512 bytes
  Concurrent copy and kernel execution:          Yes with 1 copy engine(s)
  Run time limit on kernels:                     No
  Integrated GPU sharing Host Memory:            No
  Support host page-locked memory mapping:       Yes
  Alignment requirement for Surfaces:            Yes
  Device has ECC support:                        Disabled
  Device supports Unified Addressing (UVA):      Yes
  Device PCI Domain ID / Bus ID / location ID:   0 / 3 / 0
  Compute Mode:
     < Default (multiple host threads can use ::cudaSetDevice() with device simultaneously) >

deviceQuery, CUDA Driver = CUDART, CUDA Driver Version = 7.5, CUDA Runtime Version = 7.5, NumDevs = 1, Device0 = GeForce GTX 780 Ti
Result = PASS

/ dev中nvidia文件的权限是：

crw-rw-rw- 1 root root 195,   0 Apr  3 21:18 nvidia0
crw-rw-rw- 1 root root 195,   1 Apr  3 21:18 nvidia1
crw-rw-rw- 1 root root 195, 255 Apr  3 21:18 nvidiactl
crw-rw-rw- 1 root root 244,   0 Apr  3 21:24 nvidia-uvm

为什么deviceQuery只显示1个gpu？

Answer 1

只是一个猜测，但你有没有机会设置UtcTimeStamp？

http://www.resultsovercoffee.com/2011/02/cudavisibledevices.html

Answer 2

事实证明，大多数cuda样本根本没有编码使用两张卡片。如果编码正确，则使用两个gpus。

cuda deviceQuery返回1而不是2

2 个答案: