NVIDIA graphics card driver error

1. An error is as follows

NVIDIA-SMI has failed because it couldn't communicate with the NVIDIA driver. Make sure that the latest NVIDIA driver is installed and running.
2. nvcc -v see cuda The library exists

3. see NVIDIA Whether the graphics card driver is installed

 4. install dkms, Used to dynamically load drivers ,

sudo apt-get install dkms

sudo dkms install -m nvidia -v 450.57

5.

6. Check whether the driver is loaded

7. DKMS The explanation of

Oikawa Et al. 1996 Put forward a method with LKM Similar dynamic core modules （DKMs） technology . And LKM equally ,DKMs It is stored in the form of file and can be loaded and unloaded dynamically during the operation of the system .DKMs By a User level Of DKM Server to manage , Not by kernel To manage . When the core needs a module , from DKM The server is responsible for sending the corresponding DKM load ; When the core memory resources are scarce , from DKM The server is responsible for uninstalling an unused DKM. 

8. summary

The reason is that when I run deep learning code , Called someone else's code , There are calls in it CUDA Instructions , If the driver does not match the current version of the graphics card , This will happen .