Originally Posted by biiuser
I wonder why I often run on low memory
The stats you quoted do not indicate you are on low memory.
Memory allocation is not the simple "used vs. free" that most people expect.
If you need to think about memory with a simple "used vs. free" viewpoint, then you should add the Cached and Buffers value to free.
The most meaningful single measure of free memory is the sum of MemFree, Buffers, and Cached.
That does not mean that sum really measures the amount of free memory. Memory use is too complex for any one value to really represent the effective amount of free memory. That sum just is the closest you can come to a single number that is a meaningful measure of free memory.
Since that sum is well over half your total memory (in the example you posted), you don't need to worry about subtleties of whether that exactly measures the effective amount of free memory. It is reliably telling you that you have plenty of free memory.