Help with identifying memory usage

I’m trying to determine memory usage on my dedicated server, as I think that Virtualmin GPL is potentially getting it wrong, but maybe its just the way I’m interpreting the values given.

When I load into Virtualmin GPL I can see this: Real memory 7.90 GB total, 324.06 MB used

However when I run ‘top’, I get this: Mem: 8287684k total, 2013560k used, 6274124k free, 105308k buffers

Is Virtualmin reporting back an incorrect figure, or does ‘top’ take into account other services that Virtualmin isnt?



Hi Paul,

First, just to be extra-sure, try clicking “refresh system information” on the top of that page.

Once you’ve done that, what does it show for “Real memory” and “Virtual memory”?

And, what does the command “free” output on your system?

I’ll run through the various outputs:

Virtualmin output following “refresh system info”:

Real memory 7.90 GB total, 412.21 MB used
Virtual memory 509.87 MB total, 0 bytes used


Mem: 8287684k total, 4281720k used, 4005964k free, 143436k buffers
Swap: 522104k total, 0k used, 522104k free, 3724928k cached


         total       used       free     shared    buffers     cached

Mem: 8287684 4281812 4005872 0 143436 3724928
-/+ buffers/cache: 413448 7874236
Swap: 522104 0 522104



Aha! I had almost forgotten about this, but I believe what they’re doing is accounting for buffers/cache in those calculations.

From what I understand, both buffers and cache imply a temporary usage of memory – only up until the point when the Linux kernel realizes it’s needed for something else.

So technically, memory reported in buffers/cache is actually “free” – Linux is just making temporary use of it while it’s sitting there not doing anything.

If you take the memory used as provided by “free”, then subtract that shown in both buffers and cache, you get a number very similar to what Virtualmin is showing there.

Ah yes, I understand. I’m only really questioning as I’m trying to determine the source of a potential memory leak, and I noticed that the values weren’t correlating.

Thanks for the heads up :slight_smile: