[Bug]: MemoryPlugin on Linux uses MemFree only and ignores reclaimable buff/cache (MemAvailable)

[mwessman-amd]

Summary

On Linux, MemoryPlugin appears to evaluate memory pressure using only MemFree from free -h, and computes used memory as mem_total - mem_free. This ignores reclaimable page cache/buffers that Linux can free under pressure.
As a result, the plugin can report memory usage as too high (or free memory too low) even when MemAvailable indicates there is still sufficient usable memory.

Here is a screenshot of free -h showing low free but much higher available. This is very common for our AMD cluster nodes:

Steps to reproduce

1. Run on a Linux host with significant page cache (common on long-running systems).
2. Check memory view:
   free -h
   • free is relatively low
   • buff/cache is high
   • available is significantly higher than free
3. Run MemoryPlugin:
   node-scraper run-plugins MemoryPlugin --ratio 0.90
4. Inspect the plugin result/log output for memory values and analysis status.

Version

1.1.6

Install method

Editable install from source (pip install -e .)

Python version

3.12.3