Archimedes Gaviola wrote: > With net.isr.direct=0, my IBM system lessens CPU utilization per > interface (bce0 and bce1) but swi1:net increase its utilization. > Can you explained what's happening here? What does net.isr.direct do > with the decrease of CPU utilization on its interface?
The system has a choice between processing the packets in the interrupt handler (the "irq:bce" process) or in a dedicated network process (the "swi:net" process). This is about protocol handling not simply receiving packets. With net.isr.direct you're toggling between those two options. If "direct" is 1, the packets are processed in the interrupt handler; if it's 0, the processing is delegated to swi. It's set to 1 by default because this setting should yield best latency. In both cases the code path a packet must go through is very similar: it has to be received, then processed through firewalls and network stack code, then delivered to application(s), so it's a serial process. There are things that could be better parallelized in the stack and people are working on them, but they will not be finished any time soon.
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