Please explain FreeBSD 8.0/ZFS memory usage patterns

[Ivan Voras]

Benjamin Lutz wrote:
> Hello,
> 
> I've set up a FreeBSD-8.0/amd64 system with ZFS as a home server, and I'm a 
> bit puzzled by it's memory usage pattern; I'm seeing total memory usage 
> oscillate between roughly 50% and 90% of my RAM. So I've tracked memory 
> usage over the course of about 12 hours and graphed it here:
> 
> http://www.maxlor.com/temp/mem.png

How do you get those categories: kern, proc? I suppose proc could be sum 
of resident sizes of processes (aka "RES" in top) and kern could be 
sysctl vm.kmem_size?


> In the first half of the graph, there's a torrent download running, which I 
> assume causes the large fluctuations in memory usage. However, memory usage 

Large fluctuations in which category? The ARC? (since "proc" doesn't 
fluctuate much).