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Does irqbalance add kernel module? How a user space daemon is able to assign interrupts to different processors? If it is a user space process that is doing it, won't kernel to user space context switch delay the interrupt processing?

kalyan
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irqbalance does not add a kernel module. It is a daemon.

irqbalance does not assign IRQs to specific pieces of hardware, it just maps those IRQs to CPUs dynamically. So, if eth0 was assigned IRQ 28, irqbalance would periodically move IRQ 28 from CPU0 to CPU1 to CPU2 to CPU3 to CPU0...

You could do the same thing by hand by writing the CPU affinity mask to "/proc/irq/${IRQ}/smp_affinity".

There could be some delay for an interrupt coming to a CPU if the affinity was changed at the same time, but I'm guessing that would be similar to any process that experienced a context switch.

bgoldberg
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