Cache memory

[iptrust]

Hi,

Hardware: Athlon 3800+ 2gb ram

When i go to statistic pages i can see:

memory usage: 1,7 gb !!!
cach 1mb

My question:

1/How can i have 700mb used (without cach) for only 8 small site (max 50 people in the same time on the server) !!!!

2/ how to empty the cache?

thanks

 

[eilko]

don't worry. this is the standard way of memory usage on a linux machine.

 

[Cranky]

The linux kernel is designed to use as much RAM as is available for cache and buffers so after rebooting typically your RAM will gradually be used until it reaches near-100%. If you run 'free' via shell you will see a buffers/cache column, this RAM is typically free for use if needed. Are you saying that this column only shows 1MB?

You need a memory upgrade when your swap begins to grow to more than 10-20% as swap is much slower than RAM due to it being based on your hard-disk.

 

[phatPhrog]

swappiness

I have finally found that SWAP is being used/abused by apache and/or mysql.

At first I thought it was WordPress or Drupal but after making 5 successive posts to both sites at the same time, the swap didn't change.

Normal traffic however seems to drive up the swap usage dramatically.

Example

Mem: 1026700k total, 1013612k used, 13088k free, 296k buffers
Swap: 2048276k total, 262976k used, 1785300k free, 33108k cached

This particular example doesn't show the problem, unfortunately.

We had server/site problems so we restarted apache and mysql to clear the swap and this is a result of only 5 minutes after the restart. Before restarting apache/mysql the SWAP was at 100%

Currently our /proc/sys/vm/swappiness is set to the default of 60

What is an optimal setting to keep the swap from maxing out on an FC4/Plesk 8 box. (new image with all updates and patches applied)

 

[phatPhrog]

SWAP cache Memory

K. In the interim I modified the /etc/my.cnf with

query_cache_type=1
query_cache_size=10m

just below

socket=/var/lib/mysql/mysql.sock
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).

So, you would insert it like this:

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).

query_cache_type=1
query_cache_size=10m

COURTESY of AtomicRocketTurtle

Since restarting mysql the SWAP has NOT been overwhelmed.

This, as said is interim. Until further testing is done; perhaps this resolves the issue and perhaps not.

This is working, so far on a new image of P8/FC4, Linux 2.6.16-rc6-060427a, all updates, patches. php 5.0.4-10.5, mysql 4.1.16-1.FC4.1