If you A) only run as many jobs in parallel as you have cores, and B) run them under both nice and ionice, Then you should achieve your goal without any manual intervention. This, of course, does not produce maximum efficiency. -Adam

Trevor Cordes trevor@tecnopolis.ca wrote:

(A real question this time!)

I have a web (+ other tasks) server that sometimes does a lot of tasks in a short time that spike the load up to large values (like 30). The tasks are all long jobs of lots (tens of thousands) of little (10/s) jobs. I've written code to, between each little job, check the /proc/loadavg load (1 and 5 min) and insert usleeps (.5+ secs) based on the loadavg (exponential relationship). My goal is to keep the load < 2.0 on a 2 core system.

Anyhow, it seems to be working fine. The weird thing is, at 2.0 loadavg, looking at top, I see the CPUs mostly at idle. Not even very much wait going on. Why would the load be 2 when both CPUs are mostly at 5-10% including wait?

I basically want to make sure the system doesn't get overloaded and can respond to non-batch request (like a web hit) promptly. What loadavg should I target if not (1.0 * numcores)? I guess I can arbitrarily pick numbers and see what happens, but I like things like this to make sense, and to me 1.0 * numcores makes sense, unless I'm not understanding loadavg properly.

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