Home ยป Freeing up memory (RAM) on Ubuntu 8.04 Server [duplicate]

Freeing up memory (RAM) on Ubuntu 8.04 Server [duplicate]

Solutons:


You will notice that some of that is being consumed by “cache”.

This is just disk read/write being cached and you can basically assume its free because it will be dumped out as soon as something more important needs it.

It makes disk IO faster. ๐Ÿ™‚

I have presently 2G of disk cache on my box, makes things fast.

“free” is a poor memory analysis tool. I find “htop” a much more practical overall system management tool, which gives both a practical representation of memory use and a practical way to explore processes.

Like this, just prettier:

1  [|||||                                                                          5.0%]  Tasks: 156 total, 2 running
2  [|||                                                                            2.5%]     Load average: 0.29 0.30 0.31
Mem[|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||     1182/3967MB]     Uptime: 5 days, 16:25:36
Swp[||                                                                        37/2000MB]
Mem:3967M used:1182M buffers:0M cache:1952M

( if you’re wondering about the low uptime.. thats a laptop )

A lot of people might provide ways to negate caching to get stuff out of swap, but its more or less pointless. All you’ll end up doing is reducing performance, unless you have a program that is really memory intensive , but only runs intensively every few days so that when its not running intensively it gets swapped out, and when it does come on, you cant wait the ~.5 seconds it takes to swap it back into memory from disk.

I personally can’t think of any good program that matches these conditions. shrugs

The people whom wrote the kernel know more or less what they’re doing in this department, I’d trust their judgment unless you’re certain you know better.

as @Paul Betts said, Switching to lighttpd might help you save a bit. Depends on what you’re doing, there are always a few tradeoffs.

I’m using it on my vps. Only has 96M ram and 63M swap, and its only using 26M(no joke) and 35M respectively. And there’s a database running there as well. ( Postgres , but not really used )

Ignore the first line. The important numbers are on the “-/+ buffers/cache” line. Linux will clear cache and buffers to make way for processes.

My Debian server routinely shows between 2 and 10 megabytes of free space on the first line. The second line shows that I have 50 megabytes free. (With a total of 256 ram on the system)

Your numbers look fine. DO NOT clear your buffers/cache. You have more than enough free ram.

Now if you have no memory free for cache, your system will run slow. If you start using alot of swap you’re going to have problems serving webpages.

you need to change your swappiness (tells the kernel how much it should swap)

# sysctl -w vm.swappiness=0

setting it to 0 will tell the VM to keep as much data in memory as possible, but you need to go and read up on whats right for you, its hard to tell, but do some experimenting and see what you can come up with.

edit the vm.swappiness line in /etc/sysctl.conf to set it up at boot

in other words, you want to use the memory as much as possible and reduce the amount of swapping that occurs on disk

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