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devnull3d 15th January 2008 09:57

Memory usage on debian etch
Hello, everytime i restart this box the memory usage goes up every minute according to top, until it uses 36K of swap and then stops.
I can't see the process that uses the memory, check this out

$ ps aux | awk '{print $5}' > mem
$ b=0;for a in `cat mem`; do b=`expr $b + $a` ; done;echo $b
expr: non-numeric argument # because the first line is VSZ

So that's around 512MB. I have 1GB ram and when I run top I see this

Mem:  1027412k total,  996588k used,    30824k free,  154012k buffers
Swap:  2650684k total,      36k used,  2650648k free,  744516k cached

I've never seen this before, any ideas? The kernel is 2.6.18-5-686, the processor is core duo 2 T5500 if that helps.
I tried restarting, all my processes at start up run, mysql, courier, apache, proftpd, sshd etc and their memory usage isn't changing at all. But in few hours suddenly I've used up all my memory and the box starts to swap.
Thank you.
Before you jump to a conclusion that my box might be compromised, this box doesn't have access on the internet, it's deep inside my LAN.

falko 16th January 2008 11:53

I don't see anything unusual here. Linux tries to put as much as it can into memory to be faster. That's why almost all your RAM is used, even if the sum of the single processes need less memory. And I wouldn't worry too much about 36k swap.

devnull3d 16th January 2008 12:35

Well that makes sense, I've never run such much services before so I guess you're right. But what if the server suddenly gets a lot of load from apache? Will it start to swap like crazy or it will use the physical memory more sensibly than now?

devnull3d 16th January 2008 16:28

Well the free -m output explains it all

total      used      free    shared    buffers    cached
Mem:          1003        974        29          0        150        723
-/+ buffers/cache:        100        903
Swap:        2588          0      2588

That's 723MB cashed memory, so my box is pretty healthy. I was over paranoid because I'm setting up this box to sell shared hosting and I don't want to screw people over if the box starts to swap aggressively.

falko 17th January 2008 17:19


Originally Posted by devnull3d
Will it start to swap like crazy or it will use the physical memory more sensibly than now?

It will use the physical memory. :)

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