Huh? What if I have a 48 core AMD server? A fully CPU-bound load average of 48 would be great.
Load average can tell you if the system is under-used, but it can't tell you how the system is over-used.
I regularly have a few dual core systems spike to load averages of 50+ because of suboptimal NFS mounts. The NFS issue keeps processes waiting around with nothing to do for a while. Those processes are still counted towards the "load" even though they have no CPU activity (they are blocked on IO).
Agreed it is not accurate for huge servers and IO bound cases but I have found it to be a good rule of thumb for a LAMP web application stack on anything from single to 8 core machines.
It is a useful metric to start digging deeper into the machine.
The Linux kernel also checks to see if there are any tasks in a short-term sleep state called TASK_UNINTERRUPTIBLE. If there are, they are also included in the load average sample.
Load average can tell you if the system is under-used, but it can't tell you how the system is over-used.
I regularly have a few dual core systems spike to load averages of 50+ because of suboptimal NFS mounts. The NFS issue keeps processes waiting around with nothing to do for a while. Those processes are still counted towards the "load" even though they have no CPU activity (they are blocked on IO).