Linux Paging Statistics Metric Explanation

by Apr 27, 2011

What exactly is “pages free/s” showing us here? Note the coloration is off – the mustard yellow color actually corresponds to bright yellow on the right hand table
I found the paging stats online help:
“Paging Statistics

This graph indicates whether or not a system is short of memory. up.time checks whether or not the pgscan rate and page-out statistics are consistently high. Use the following equation to calculate the scan rate threshold:

scan threshold = handspreadpages ÷ residence time

The handspreadpages variable is fixed at 8192 on UltraSPARC systems with more than 256 MB of memory. The residence time variable is generally fixed at 30 seconds. Therefore, the default scan rate threshold is 273.

You should also examine the swap device for excessive activity. To identify the device, check the file /etc/vfstab for the tmpfs file system. You can also use the swap -l command to list the physical partitions that are being used for swap on the system.

See Generating a Memory Usage Graph for information on how to generate this graph.”

But I am not clear how some of the metrics that show up in the graph are corresponding. I went through the sar man page as well.

Can you please help clarify what the metrics, specifically the “page free” is telling us?