Before:memory 8G, swap:8GAfter:after adding 8G memory, the swap doesn't workhow can I activate it?OS: CentOS 7, 64bit.
How to activate swap after adding more memory?
partition;swap
You can confirm that swap is activated and how much is being used with:  swapon --showAs an aside, if you want to check memory usage without htop you can use:  free  That said, what you have already shown indicates that you likely do not have any problems with your swap.