Direct answer

Linux uses spare RAM for page cache. The useful host indicator is typically MemAvailable rather than just MemFree; cached memory can improve repeated region-file reads.

How to check it

  1. Run free -h and grep -E "MemAvailable|MemFree|Cached|Buffers" /proc/meminfo on the real host where accessible.
  2. Compare filesystem cache with process RSS, JVM heap allocation and the container memory limit.
  3. Check swap activity and OOM events before concluding the operating system lacks memory.

What to change

free -h
grep -E "MemAvailable|MemFree|Cached|Buffers" /proc/meminfo
  1. Do not clear Linux page cache as a routine Minecraft optimization; it may cause slower subsequent disk reads.
  2. Focus on demonstrated memory pressure, OOM kills or swap activity rather than high used-memory numbers alone.
  3. If a container is limited, examine cgroup statistics because host-wide free may not represent its memory budget.

Software and version notes

Compatibility and safety

Cached includes some tmpfs/shmem accounting, and MemAvailable is an estimate rather than a promise. File cache is different from the Java heap and the Minecraft chunk cache.

Verify the result

Confirm stable available memory, low swap activity and no new OOM kills under comparable player load.

References