High interrupt rate even when using NAPI

High interrupt rate even when using NAPI

[Steve Modica]

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

Re: High interrupt rate even when using NAPI

[David S. Miller]

On Wed, 05 Nov 2003 12:03:46 -0600
Steve Modica <modica@sgi.com> wrote:

> I just noticed some strange behavior with the tg3 driver.

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.