Messages in this thread | | | Date | Sun, 29 Aug 2004 17:26:15 -0400 | From | Jeff Garzik <> | Subject | Re: interrupt cpu time accounting? |
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Robert Love wrote: > On Sun, 2004-08-29 at 16:42 -0400, Jeff Garzik wrote: > >>Does the kernel scheduler notice when a CPU spends a lot of time doing >>interrupt processing? >> >>For many network configurations you get the best cache affinity, etc. if >>you lock network interrupts to a single CPU. However, on a box with >>high network load, that could mean that that CPU is spending more time >>processing interrupts than doing Real Work(tm). >> >>Will the scheduler "notice" this, and increasingly schedule processes >>away from the interrupt-heavy CPU? > > > Nope, not explicitly anyhow. > > Implicitly, at least, the load balancer will ensure that the runnable > processes on the processor do not get "backed up" due to the delayed > processing but you will still have the balanced minimum number of > processes there.
What piece of code defines "balanced"? :)
> I don't know whether the answer is to use cpu affinity and not schedule > processes on that processor when you bind interrupts to it, or an > automatic algorithm in the load balance for doing it, but that is a neat > idea.
Less a neat idea, and more IMHO recognition of a problem that needs solving.
I am worried that processes will get starved if one CPU is _heavily_ loaded servicing interrupts, and the others are not.
Regards,
Jeff
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