You’ll need do that whenever your Virtual memory got 100%
The swap file is used to increase the system’s total accessible memory beyond its hardware capabilities.
This means that when all of the Raspberry Pi’s RAM is exhausted, it can start using the swap file as memory instead.
The addition of more virtual memory allows the system to deal with more memory intensive tasks without running into out of memory errors or having to shut down other additional packages.
However, the downside to this is that accessing the swap file is a significantly slower process that can create slowdowns.
The reason for this is that the swap file exists on your actual disk, which has significantly lower read and write speeds then your RAM.
Another caveat of a large swap file is that you need that space to be free on your SD Card. You can’t set a swap file on your Raspberry Pi larger than your available free space.
The swap file cannot be in use while we increase it.
To stop the operating system from using the current swap file, run the following command.
sudo dphys-swapfile swapoff
We can open this file using nano by using the command below.
sudo nano /etc/dphys-swapfile
And search & modifiy as your needed. At my side i’m using 512 ( MB )
We can now re-initialize the Raspberry Pi’s swap file by running the command below.
sudo dphys-swapfile setup
With the swap now recreated to the newly defined size, we can now turn the swap back on.
sudo dphys-swapfile swapon