Used memory - graphing calculated fields

[Hichhiker]

Is there any way to graph a calculated field like Used Memory without all the crazy work of collecting the duplicate data?

As I understand right now in order to have a graph of Used Memory you have to add a custom parameter and calculate the used memory on each request and send it to zabbix server to store it. Is there a more efficient way of accomplishing this?

Can you graph a computed value? (e.g. total - (free+cached+shared+buffers))

Can you create a calculated item so that the value comes from a math expression instead of DB?

Can you mix stacked and unstacked fields so that you can graph a stacked set of memory bits over an unstacked fill of total memory?

Can you at least set Y max to a value of an item?

Is there another way of doing this that I am missing?

Thanks

-HH

P.S. I am running 1.4.4 in case it matters

[kdx200rider]

Being able to use a gathered value, like memory total, as the fixed Y axis on a graph would be great. This way one could create a memory graph within a template and have it work on systems with different amounts of memory.