topic Linux: High memory utilisation in Operating System - Linux

Linux: High memory utilisation

SUDHAKAR_18 — Sun, 01 Nov 2009 13:30:14 GMT

Hi,

In one of my linux box consuming high memory.

I have found cache is uilising more. Its a RHEL4 linux.

Please someone help me how to clear cache & how to put threashold to that.

thanks in Advance

Re: Linux: High memory utilisation

Steven Schweda — Sun, 01 Nov 2009 16:34:04 GMT

> I have found cache is uilising more.

Perhaps because no one else wants it.

Normally, disk caching software will release
memory if anyone else wants it. Unused
memory does nothing for anyone, so why do you
want more of it?

Re: Linux: High memory utilisation

dirk dierickx — Mon, 02 Nov 2009 08:56:21 GMT

i think this question gets asked 20 times a week. a simple forum search will reveal this and you'll notice the answer to be always the same.

short: it's normal, don't worry about it.

Re: Linux: High memory utilisation

Matti_Kurkela — Mon, 02 Nov 2009 12:11:22 GMT

All modern OSs have multiple priority "tiers" for memory allocation.

The number and meaning of each allocation tier varies by OS, but in general, it works like this:

Memory used for disk cache is the lowest possible allocation tier. Memory allocation for applications has higher priority than the cache.

If an application requires memory and free memory is not available, the OS simply finds the least-recently-used cache block and re-allocates it to the application.

If the cache is "dirty" (i.e. contains data that is not yet written to disk), the OS just delays the memory-hungry application a little, sends the cache content to disk, then re-allocates the memory to the application that needed it.

Also remember: if your RHEL4 is a 64-bit version, but the software you're running is 32-bit, the software can never allocate more than 4 GB of RAM.

MK