From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nivedita Singhvi Subject: Re: [PATCH] Ethernet Bridging: Enable Hardware Checksumming Date: Thu, 19 May 2005 08:10:13 -0700 Message-ID: <428CAC55.4000202@us.ibm.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Jon Mason , shemminger@osdl.org, netdev@oss.sgi.com Return-path: To: Herbert Xu In-Reply-To: Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Herbert Xu wrote: > Jon Mason wrote: > >>checksum and scatter gather as features of the bridge device. In the >>case that the physical ethernet device does not support scatter >>gather or hardware checksum, dev_queue_xmit() will check the >>dev->features and do the necessary linearization and calculate the >>checksum. > > > Unfortunately skb_linearize is a lot more expensive than not > generating the non-linear skb's in the first place. > > So this is going to hurt people using the bridge devices over > physical devices that don't support SG. Fair point - though I would argue that devices that support SG are much more common now - so optimizing for the more common case might be preferable - since people using bridging with devices that support checksum offload are taking quite a hit when they do bridging - perhaps this could be a conditional? thanks, Nivedita