Re: Info: NAPI performance at "low" loads

From: Jeff Garzik (
Date: Tue Sep 17 2002 - 21:36:36 EST

David S. Miller wrote:
> From: Jeff Garzik <>
> Date: Tue, 17 Sep 2002 22:11:14 -0400
> You're looking at at least one extra get-irq-status too, at least in the
> classical 10/100 drivers I'm used to seeing...
> How so? The number of ones done in the e1000 NAPI code are the same
> (read register until no interesting status bits remain set, same as
> pre-NAPI e1000 driver).
> For tg3 it's a cheap memory read from the status block not a PIO.


        get-irq-stat (omit, if no work loop)


        get-irq-stat (omit, if work loop)

This is the low load / low latency case only. The number of IOs
decreases at higher loads [obviously :)]

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

This archive was generated by hypermail 2b29 : Mon Sep 23 2002 - 22:00:21 EST