Why is so much memory being used.

Here is a screen print from TOP. I have no gui running. I have squid and lotus domino running and thats about it. Why is this hoging up all the memory?


top - 13:48:13 up 3 days, 1:26, 1 user, load average: 0.00, 0.00, 0.00
Tasks: 72 total, 2 running, 70 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.9% us, 0.3% sy, 0.2% ni, 98.1% id, 0.6% wa, 0.0% hi, 0.0% si
Mem: 256136k total, 240112k used, 16024k free, 41744k buffers
Swap: 262136k total, 49704k used, 212432k free, 124484k cached

If you post the rest of the top output we can tell you what is doing this.

I cant right now as I had to ssh to get that. I am not at the site. I'll be by there later today so I check then. Nothing was really running. Domino was using about 10% mem and other than that everything was a sleep.

This kind of question gets asked a lot.

The quick and easy answer is to tell you not to worry about it because nothing is really hogging up all your memory.

The more in depth answer has to do with the way Linux does memory management.

When a program executes it gets allocated a certain amount of memory (based on a verity of things calculated at compile time). The kernel typically actually allocates it more then it asks for (never less). As time goes on programs tend to grow (aka dynamically allocated memory). When the use up the extra that was originally given to them they get more memory (pretty much always in increments of 2 pages or 8k, but getting only 4k is possible, everything will be in increments of the page size). When a program exits the OS consciously marks those pages as free, but it doesn't actually go through the long process of freeing them. It only actually goes back and reclaims the memory once somebody asks for a chunk of memory and there isn't enough room to give it to them.

Anyway, as a result once a system has been running long enough you typically see about 80-90% of the memory marked as used at all times. You only really need to be concerned about memory usage stats if your swap usage goes up significantly over a period of time. ~49MB of swap usage isn't a big deal at all for a machine that has only 256MB of memory. On my machines (which all have 1 or 2 GB) I never see any usage on swap though after a long amount of time my memory usage still reaches nearly 80% of the systems total memory.

Thanks, the reason that I was asking was my proxy server on here was running real slow so I thought that the memory was the cuplret. Thanks for the help. I understand better.