For Nvidia GPUs there is a tool nvidia-smi that can show memory usage, GPU utilization and temperature of GPU. There also is a list of compute processes and few more options but my graphic card (GeForce 9600 GT) is not fully supported.
Sun May 13 20:02:49 2012
+------------------------------------------------------+
| NVIDIA-SMI 3.295.40 Driver Version: 295.40 |
|-------------------------------+----------------------+----------------------+
| Nb. Name | Bus Id Disp. | Volatile ECC SB / DB |
| Fan Temp Power Usage /Cap | Memory Usage | GPU Util. Compute M. |
|===============================+======================+======================|
| 0. GeForce 9600 GT | 0000:01:00.0 N/A | N/A N/A |
| 0% 51 C N/A N/A / N/A | 90% 459MB / 511MB | N/A Default |
|-------------------------------+----------------------+----------------------|
| Compute processes: GPU Memory |
| GPU PID Process name Usage |
|=============================================================================|
| 0. Not Supported |
+-----------------------------------------------------------------------------+
Answer from pbm on Stack ExchangeFor Nvidia GPUs there is a tool nvidia-smi that can show memory usage, GPU utilization and temperature of GPU. There also is a list of compute processes and few more options but my graphic card (GeForce 9600 GT) is not fully supported.
Sun May 13 20:02:49 2012
+------------------------------------------------------+
| NVIDIA-SMI 3.295.40 Driver Version: 295.40 |
|-------------------------------+----------------------+----------------------+
| Nb. Name | Bus Id Disp. | Volatile ECC SB / DB |
| Fan Temp Power Usage /Cap | Memory Usage | GPU Util. Compute M. |
|===============================+======================+======================|
| 0. GeForce 9600 GT | 0000:01:00.0 N/A | N/A N/A |
| 0% 51 C N/A N/A / N/A | 90% 459MB / 511MB | N/A Default |
|-------------------------------+----------------------+----------------------|
| Compute processes: GPU Memory |
| GPU PID Process name Usage |
|=============================================================================|
| 0. Not Supported |
+-----------------------------------------------------------------------------+
For linux, use nvidia-smi -l 1 will continually give you the gpu usage info, with in refresh interval of 1 second.
For Nvidia GPUs there is a tool nvidia-smi that can show memory usage, GPU utilization and temperature of GPU.
For Intel GPU's you can use the intel-gpu-tools.
AMD has two options
fglrx (closed source drivers):
aticonfig --odgc --odgtAnd for mesa (open source drivers), you can use RadeonTop
sudo apt install radeontop radeontop
Source:GPU usage monitoring
You can use gpustat, which is a simple command-line script (wrapper for nvidia-smi) for querying and monitoring GPU status:

Videos
To get real-time insight on used resources, do:
nvidia-smi -l 1
This will loop and call the view at every second.
If you do not want to keep past traces of the looped call in the console history, you can also do:
watch -n0.1 nvidia-smi
Where 0.1 is the time interval, in seconds.

I find gpustat very useful. It can be installed with pip install gpustat, and prints breakdown of usage by processes or users.
