High interrupt rate even when using NAPI

Hi All,

I just noticed some strange behavior with the tg3 driver.

Even with NAPI enabled, during high loads of 1500 byte MTUS, I'm seeing a very high interrupt rate. To move 500kBytes/sec I'm seeing 22k interrupts/sec. It tracks very closely with the actualy throughput.

That amounts to about 1 interrupt per 23 bytes. I figured with NAPI, we should do a lot better than that.

Is there a tuneable or some driver stat that I can track to figure out what's happening here? I'd like to see that interrupt number be a lot lower.

Steve

Steve Modica
MTS-Technical Lead
"Give a man a fish, and he will eat for a day, hit him with a fish and
he leaves you alone" - me

The tg3 driver needs to poke the chip a hundred times per second in order to work around a hardware bug, eack poke causes an interrupt. This is needed regardless of whether the chip is processing packets or not.