Subject: Re: e1000 full-duplex TCP performance well below wire speed

From: Rick Jones <[email-masked]>
Date: Thu, 31 Jan 2008 10:38:32 -0800

> A lot of people tend to forget that the pci-express bus has enough bandwidth on
> first glance - 2.5gbit/sec for 1gbit of traffix, but apart from data going over it
> there is significant overhead going on: each packet requires transmit, cleanup and
> buffer transactions, and there are many irq register clears per second (slow
> ioread/writes). The transactions double for TCP ack processing, and this all
> accumulates and starts to introduce latency, higher cpu utilization etc...

Sounds like tools to show PCI* bus utilization would be helpful...

rick jones