SuperKaramba Memory Sensor Incorrect

[James Wells <me@lazyjames.co.uk>]

Hi all,

I noticed that SuperKaramba reports memory usage differently to the free and 
vmsize commands when you select the format="%umb" option (described as "Used 
memory in megabytes (cache and buffers excluded)." on the SuperKaramba 
sensors page [1]). 

The memory usage appears to be considerably lower than that reported by the 
free command. For example, at the moment free outputs the following:

             total       used       free     shared    buffers     cached
Mem:        386948     383360       3588          0      26488     105076
-/+ buffers/cache:     251796     135152
Swap:       562232     355856     206376

whereas my SuperKaramba theme reports the used memory excluding cache and 
buffers to be 210Mb (instead of 251796/1024=246Mb).

I had a look at the source code in the Debian package. The memory usage is 
found by parsing the /proc/meminfo file. The MemSensor::getCached() function 
calculates the amount of cache as the total "Cached" and "SwapCached" memory 
and the free memory is calculated using this value. This means that the 
reported free memory is lower than that reported by "free" by the amount of 
SwapCached memory. I'm pretty sure that this is wrong as SwapCached relates to 
the swap partition rather than the physical memory, but I wanted to run it 
past you guys before filing a bug. Also, is this better filed with the Debian 
BTS or upstream?

Using pure Sid, stock kernel 2.6.8, SuperKaramba version 0.35-2.

Cheers

James Wells

[1] http://netdragon.sourceforge.net/ssensors.html