From mboxrd@z Thu Jan 1 00:00:00 1970 From: "David S. Miller" Subject: Re: How to count tx and rx bytes? Date: Mon, 15 Dec 2003 14:17:29 -0800 Sender: netdev-bounce@oss.sgi.com Message-ID: <20031215141729.15387fc1.davem@redhat.com> References: <3FDE13AE.3050402@candelatech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@oss.sgi.com Return-path: To: Ben Greear In-Reply-To: <3FDE13AE.3050402@candelatech.com> Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org On Mon, 15 Dec 2003 12:03:58 -0800 Ben Greear wrote: > Is there an agreed upon standard for exactly what ethernet drivers > should be counting for rx-bytes and tx-bytes? For example, should the > counters include the 4-byte FCS? Should they include the ethernet header? Good question. It should be that all drivers use what skb->len ends up with at rx/tx time. However, it is often faster to just let the hardware keep track of these statistics (tg3 is one example of a chip that can do this). And sometimes these mechanisms take the FCS or whatever into account and this as you note makes the numbers different.