ps_mem.py vs top - memory usage?

Question

Every now and again my apache server is crashing, getting an error saying the MaxClients has been reached. In my research I've gained the impression that I may be running out of memory (just checked and MaxClients is set to 1500, though number of apache processes hovers between 40 and 100)

Anyway that's just a bit of background.

When I run top I am told I've about 15GB in total, 14GB in used and the Free seems at the moment to be hovering between 500MB - 1GB (though about an hour earlier it was about 3-4 GB free)

I have also run ps_mem.py however and that shows only 3-4 GB being used!

Why the difference? And which one is correct?

What do tools like `free` and `vmstat` report? Are you counting buffer space? What linux kernel version? — Andrew Domaszek, Nov 28 '14 at 00:16
`free` and `vmstat` are similar to `top`. Kernel: 3.2.0-72-virtual — komodosp, Nov 28 '14 at 08:50
Right Now: `top` / `free` - Buffers - 2.5GB, Cached - 5.8GB - Free 300MB - 15GB total `ps_mem.sy` - 2.5GB — komodosp, Nov 28 '14 at 08:57

Hrvoje Špoljar · Answer 1 · 2014-11-27T23:34:04.183

0

ps_mem.py is IMO bit more precise because it assesses amount of shared memory correct where top is buggy.

top reads /proc/<PID>/statm whereas ps_mem.py reads more detailed info from /proc/<PID>/smaps and assesses total usage of multi-processing daemon with more precision.

For details I recommend reading through ps_mem.py code

edited Nov 27 '14 at 23:34

answered Nov 27 '14 at 23:07

Hrvoje Špoljar

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why the downvote? – Hrvoje Špoljar Nov 27 '14 at 23:18

ps_mem.py vs top - memory usage?

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