What Are MemAvailable and MemAvailable?

When you run cat /proc/meminfo, you may pay more attention to the MemFree and MemAvailable fields in the output. The following describes the two fields.

1. MemFree: Physical memory that is not used.
   • It is the number of unallocated pages in the buddy allocator.
   • MemFree does not include the memory used as a page cache, slab cache, or buffer.
2. MemAvailable: Memory that can be used by applications, estimated by the kernel depending on the possibility of cache reclamation. MemAvailable includes:
   • MemFree
   • Most page caches (reclaimable)
   • Reclaimable slab cache
   • min_free_kbytes (minimum amount of free memory)
     

     A small MemFree value does not mean the system is about to run out of memory (OOM). As long as there is sufficient reclaimable memory and swap, OOM will not occur even if the value of MemFree is small. The OOM risk depends on the value of MemAvailable.