[collectd] swap plugin improvements

[Aurélien REYNAUD]

Hello,

> -----Message d'origine-----
> 
> I would say you want to get numbers that match swap -l.  (the last two
> numbers are blocks allocated and blocks free of just swap.)
> 

To be clear on the subject, the solaris swap command can be run with one of
the two arguments -l or -s.

Run with -s it behaves like the current swap plugin implementation
(libkstat) and gives results about the solaris swapfs, which consists of the
swap space provided by the swap devices (disks) plus a variable amount of
RAM: 

root at uv8801xr:/root> swap -s
total: 7468592k bytes allocated + 6127480k reserved = 13596072k used,
7109144k available

This can be useful for advanced sysadmins who have a good understanding of
the solaris internals, as it implies being familiar with virtual memory, or
the behavior of tmpfs (RAM/swap based filesystem). I personally find the
resulting graphs confusing, as they show the usage of something which varies
in time and is neither swap size nor any obvious combination of swap and RAM
sizes.


Running swap -l is more straightforward. It just gives a list of disk-based
swap devices and their usage, which I think is what most admins expect:

root at uv8801xr:/root> swap -l
swapfile             dev  swaplo blocks   free
/dev/vx/dsk/swapvol 242,5      16 24576704 23138752


I suppose the solaris swap utility internally uses either the libkstat or
the swapctl method according to the option given in argument.



Regards,

Aurelien Reynaud