Charting server load

[Ian Petersen]

> Of course a system with a load of 50 might be doing fine and be
> perfectly responsive, while another with a load of 5 might be bogged
> down with too much memory and disk io and be very slow at responding.

I can see how a system with high load might still be responsive
because I would define responsive as "responds nearly immediately to
user input" where "user input" could be defined as key presses, mouse
movements, ssh connection requests, etc.  This could easily be
accomplished by running user-facing processes at high priority so that
user input forces the relevant processes onto the CPU.

On the other hand, a non-hyperthreaded, single-core uniprocessor can
still only do "one thing at a time", ignoring vector instructions, so
if, for the last minute, there was an average of 50 ready processes in
the run-queue, how is that not "overloaded"?  A load of 50, to me,
means that at any given moment the kernel had 50 things to do but had
to pick one (or N on an N-core system).  If I had 50 things to do at
any given moment and was restricted to doing only one at a time, I'd
feel pretty stressed.

Ian

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