NAPI (was Re: Linux 2.4.20-pre1)

From: Jeff Garzik (
Date: Tue Aug 06 2002 - 12:12:04 EST

Marcelo Tosatti wrote:
> I want arguments from Davem to include NAPI. Changing the drivers is a
> reason for me to _not_ want it in.
> But lets see if Davem can convince me ;)

8139too needs it for flood protection. I also have a patch for sundance
which fixes the issue with the quad port and implements RX polling for
flood protection.

Basically, NAPI --should not-- affect any system that is not using a
NAPI driver. Think of NAPI as a net driver libary -- if your driver
doesn't use it, you don't know it's there at all. And currently tg3 is
the only 2.4 driver using NAPI.

NAPI saves people manually implementing polling in each driver, for
flood and DoS protection that is needed in 2.4. The flood ceiling is
much lower without NAPI, due to having the CPU overhead of interrupt
handlers. NAPI also eliminates the need for lots of code to support all
sorts of NIC hardware interrupt mitigation variants.


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