Err.. memory going crazy

http://www.linuxatemyram.com/ !

Oh I see. I remember reading a slicehost article and I thought it was the third row for "free" on memory. i guess it's the second row. Thank you!

On this topic, I can't figure out why I'd be using swap when there's plenty of free memory?

> free -m

total used free shared buffers cached

Mem: 540 464 75 0 41 276

-/+ buffers/cache: 146 393

Swap: 383 20 363

> top

top - 11:42:33 up 5 days, 2:58, 1 user, load average: 0.14, 0.16, 0.12

Tasks: 89 total, 2 running, 87 sleeping, 0 stopped, 0 zombie

Cpu(s): 0.8%us, 0.3%sy, 0.0%ni, 98.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

Mem: 553184k total, 476328k used, 76856k free, 43168k buffers

Swap: 393208k total, 52k used, 393156k free, 283088k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

2330 mysql 15 0 77808 53m 4928 S 0 9.9 38:14.19 mysqld

22016 www-data 15 0 165m 42m 24m S 0 7.9 0:00.98 apache2

22015 www-data 15 0 156m 26m 18m S 3 4.8 0:00.70 apache2

22032 www-data 15 0 156m 25m 16m S 0 4.7 0:00.74 apache2

22031 www-data 15 0 155m 24m 17m S 0 4.6 0:00.84 apache2

22030 www-data 15 0 153m 10m 5988 S 0 2.0 0:00.17 apache2

22027 www-data 15 0 152m 9996 5164 S 0 1.8 0:00.06 apache2

22041 www-data 20 0 152m 9536 5176 S 0 1.7 0:00.03 apache2

22040 www-data 15 0 152m 9524 5132 S 0 1.7 0:00.04 apache2

2514 root 18 0 151m 8056 4812 S 0 1.5 0:10.67 apache2

2599 root 15 0 6816 4956 1544 S 0 0.9 0:00.96 munin-node

2713 root 18 0 23288 4000 1592 S 0 0.7 0:01.03 fail2ban-server

and then after reloading apache

> free -m

total used free shared buffers cached

Mem: 540 473 66 0 42 276

-/+ buffers/cache: 154 385

Swap: 383 0 383

@Moses:

On this topic, I can't figure out why I'd be using swap when there's plenty of free memory?

> free -m

total used free shared buffers cached

Mem: 540 464 75 0 41 276

-/+ buffers/cache: 146 393

Swap: 383 20 363
You're using 20Mb of swap. This is a feature of the Linux kernel to throw things out that really aren't in use. Even when you have free memory Linux can swap stuff out that really isn't in use.

My real machine at home has 4Gb RAM, currently has 182Mb in use and has swapped 200Kb. My linode 360 has 40Mb in use, but has 5Mb swapped. My Panix v-colo 360 has 43Mb in use and 4Mb swap.

It's just how Linux tries to optimise memory usage. That 20Mb of swap space used means 20Mb of extra RAM for real usage.

Thanks for that info sweh, seems obvious when you know the answer!

If you want to reduce the chance of swap being used run

sysctl -w vm.swappiness= To make this persistent after a reboot use the following

echo "vm.swappiness=" > /etc/sysctl.d/60-swappiness.conf

The lower the number the less chance of swapping, 0 switches it off. I have it set at 30, I think the default is 50.