Summing RSS Is Not Your WSL2 Memory Usage
Task Manager says "VmmemWSL" is holding 8 GB, while inside Ubuntu, "htop" shows something closer to 2 GB. At first, the difference is difficult to interpret because both numbers look perfectly plausible when considered on their own. You close a few browser tabs, stop a container, run "wsl --shutdown", and perhaps even try a ".wslconfig" setting you found in a forum post. Yet, somehow, the numbers…
Task Manager reports 8 GB of memory being used by VmmemWSL, but running htop inside Ubuntu shows around 2 GB. It can be confusing why these numbers differ, but the key is understanding the different scopes they represent. Windows looks at the machine as a whole at the host level, while VmmemWSL represents the WSL2 virtual machine, including the VM's memory footprint, Linux kernel, caches, and workloads.
The Linux environment sees what a particular distribution has at the distro level, and individual processes and their memory mappings are described at the process level. Comparing these numbers directly is a category error because they are describing different things. After recognizing this, it became clear that adding up RSS values from multiple processes does not give the accurate memory usage of WSL2.
The reason is that RSS, or Resident Set Size, does not represent unique physical memory ownership. A process maps pages that may also be mapped by other processes, causing shared pages to be counted multiple times. Scaling this up across many processes, shared libraries, and memory mappings leads to over-counting physical memory.
Consequently, the total RSS value can become larger than the actual memory footprint of the WSL2 virtual machine. This highlights the importance of understanding the scope and meaning of each memory measurement before attempting to compare or aggregate them.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.