topic Re: release memory in Operating System - Linux

release memory

Ryan Lee — Tue, 17 Oct 2006 22:23:27 GMT

Hello

I used a RHEL21 NOS and running vsftp server. I also know when save and get file via ftp. the memory will hold until next file. so our system always used over 90% memory usage with not any problem. but we have a new monitoring tools to check memory.
Would you help me how to turn down memory. I know the sysctl can turning vm. But I know which one item of sysctl can release. Please suggest me to try to release memory when the RHEL2.1 used over 60-70% memory.

Thanks
Ryan

Re: release memory

Steven E. Protter — Wed, 18 Oct 2006 01:42:55 GMT

Shalom Ryan,

The whole princple behind this question needs to be called into question.

90% memory use is not a problem on a Linux system. It is an efficeint use of resources you paid money for.

As long as the system is providing service with a reasonable response time, there is no need to worry about actual memory use. When memory is not needed by applications, the system can use it to improve performance.

Jumping through hoops to make measurement software happy is likely to create a problem where none exists.

If you could add some reasoning, I'll check back on this thread and try and provide you more deataild assistance.

SEP

Re: release memory

Atul Gautam — Wed, 18 Oct 2006 02:43:29 GMT

Hey Ryan,

You can take a look at all the kernel parameters using the command "sysctl -a".

I've listed few kernel parameters that can be changed using the "sysctl" command itself and they can also be saved in "/etc/sysctl.conf" file and then kernel can be directed to that file using the command "sysctl -p /etc/sysctl.conf".

The kernel parameters for Physical and Virtual Memory are ---

Physical Memory
================
1) kernel.shmall
=> available memory for shared memory in 4K pages
2) kernel.shmmax
=> maximum size of one shared memory segment in byte
3) kernel.shmmni
=> maximum number of shared segments

Virtual Memory
===============
1) vm.min_free_kbytes
2) vm.swappiness

Here's a link for you for cross reference purpose as to how Memory Management task in Linux is accomplished.

http://www.redhat.com/magazine/001nov04/features/vm/

Atul

Re: release memory

Michal Toth — Wed, 18 Oct 2006 15:57:38 GMT

man ulimit