topic memory usage via sar in Operating System - Linux

memory usage via sar

Joseph Hoh — Wed, 29 Jan 2003 19:39:36 GMT

When I check for memory usage with sar (or top) on my RedHat 7.1 system it shows that memory usage is 99%. It shows the same usage on a system that has nothing other than OS running on it. There appears to be no swapping going on. Why does it always show memory being 99% used?

Re: memory usage via sar

Steven E. Protter — Wed, 29 Jan 2003 19:59:49 GMT

Having no demands for memory in other area,certain software grabs what it can get.

using oracle perhaps?

Here is a sar collection script tested on HP-UX that will let you collect data over a long time period. The script will need adjustment if sar options don't work the same on Linux as HP-UX.

It could prove useless, but if sar is the same, it will collect some really slick data for you. collecting for longer time periods gets you better averages.

P

Re: memory usage via sar

Stuart Browne — Wed, 29 Jan 2003 23:43:59 GMT

What does /proc/meminfo show?

This is the same information that 'top' and 'sar' show up, but in a different manner.

In particular, what I'm wanting to know is what the 'Buffers' line says.

Linux (unlike SCO Unix atleast, and I think HP-UX, but am not sure) automatically and dynamically assigns disk buffers when there is available memory.

If the machine isn't swapping, don't worry about the amount of free memory.