host memory usage

[Gerolamo Valcamonica <ge...@pyder.com>]

Hi Everybody,
I have a cloudstack 4.1 cluster.
Host features goes from two 5-year-old quad core xeon with 4 Gb Ram to two
1-year-old six core hyperthreaded xeon with 32 GB Ram

All hosts run same linux version (3.8.0-19) and same libvirt version (1.0.2)

On one of the smallest host (the "4 Gb ram" ones) I have 2 user VM, each 
one with 768 MB ram, and three virtual routers

As far as I know, memory usage should be:
host memory usage (?) + 768 + 768 + 128 + 128 + 128 =
host memory usage + 1920

Infact, when I call the listHosts API, I get 1920 in memoryallocated field.

But, if I log in into host I have:

KiB Mem:   4048996 total,  3605360 used,   443636 free,    14416 buffers
KiB Swap:  4190204 total,  1473024 used,  2717180 free,   107424 cached
that is far more than i expected, on memory usage!

So, the question is: how much memory does hosts need?

The worst is that if i create another user VM on that host, swap usage
becomes consistent and all VMs (and routers) become very slowed

Any idea?

-- 
Gerolamo Valcamonica