What Memory is Service Console Using?

[scotty_p]

When I connect to the service console, I see that 700 of 800MB memory is in use when I run "free -m". If I do a top or a ps -aux, there really isn't anything that's consuming much memory (other than hostd-worker - 12%). Is there a way to determine what is using so much memory? 700MB seems higher than it usually runs.

Thanks,

Scott

[mcowger]

Are you looking at the first line or at the +/- buffers/cache line?

The buffers/cache line is realyl what you want for accuracy of processes using memory.

[scotty_p]

Thanks for the response.  I've been looking at the Mem line. Below is what I'm seeing. Is that line not accurate? We also monitor memory on these servers with a 3rd party tool and it is alarming because it sees high memory usage. Is there really not 661MB used? Thanks.

free -m
                  total       used       free     shared    buffers     cached
Mem:           783        661        121          0        174        316
-/+ buffers/cache:        170        612
Swap:         1200          0       1200

[mcowger · Accepted solution]

This is a common Linux-ism/mis conception.

The sytem is using 661MB memory.  However, only 170MB is being used for applications.  Linux will aggressively use any otherise-unused memory for filesystem caching, which is what you see there under 'buffers' and 'cached'.  At the point that an application requests more memory, Linux will reduce the buffer and cache sizes and give it over.  Here's a similar explanation: http://www.linuxatemyram.com/

So if you want to monitor memory usage, you need to monitor (USED - BUFFERS - CACHE), which is what that second line gives you.  So realistically, your system is using 170MB for actual applications, and the rst for filesystem caching.

[scotty_p]

Wow! I had no idea that was the case. i guess we're monitoring the wrong thing.

Thanks for the insight.