Some things in top's output are pretty straightforward, like memory and swap usage. But load average numbers are a bit of a mystery: what do these three numbers mean? Also, what exactly is a zombie process and how is it different from a sleeper?
top - 13:20:58 up 69 days, 7:07, 1 user, load average: 0.03, 0.02, 0.00 Tasks: 80 total, 1 running, 79 sleeping, 0 stopped, 0 zombie Cpu(s): 0.0% us, 0.2% sy, 0.0% ni, 99.8% id, 0.0% wa, 0.0% hi, 0.0% si Mem: 8054888k total, 7975100k used, 79788k free, 130240k buffers Swap: 1572856k total, 84k used, 1572772k free, 6393160k cached
Load average reference.
Zombie process reference.
The 3 load average numbers is the load your system has been under for the past minute, 5 minutes, and 15 minutes.
I'm not exactly clear on how load is calculated - but it has something to do with how many processes are demanding cpu time at once. A server that is running consistently below 1.0 means it has no processes waiting for the cpu (ie. it is running at maximum speed)