memory 8G, swap:8G
after adding 8G memory, the swap doesn't work
how can I activate it?
OS: CentOS 7, 64bit.
You can confirm that swap is activated and how much is being used with:
As an aside, if you want to check memory usage without htop you can use:
That said, what you have already shown indicates that you likely do not have any problems with your swap.
The Swap is configured correctly and we can see it in the image posted.
There is no separate step to activate swap. Swap is used only when system runs out of RAM. Your system has enough RAM for all the running applications.
The image you have posted shows that there is 7.75GB of swap and not used.