From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] net: Add ndo_gso_check Date: Tue, 07 Oct 2014 16:32:39 -0400 (EDT) Message-ID: <20141007.163239.157997964784151921.davem@davemloft.net> References: <20141007.144752.657165589422333613.davem@davemloft.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: therbert@google.com, jesse@nicira.com, gerlitz.or@gmail.com, alexander.h.duyck@intel.com, john.r.fastabend@intel.com, jeffrey.t.kirsher@intel.com, netdev@vger.kernel.org, tgraf@suug.ch, pshelar@nicira.com, azhou@nicira.com To: alexei.starovoitov@gmail.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:48388 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751712AbaJGUcm (ORCPT ); Tue, 7 Oct 2014 16:32:42 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: From: Alexei Starovoitov Date: Tue, 7 Oct 2014 13:28:01 -0700 > On Tue, Oct 7, 2014 at 11:47 AM, David Miller wrote: >> >> I am totally against boolean "yes/no" protocol specific checksum >> validation by HW. >> >> It's not faster. You have to look at the pseudo-header and bring it into >> the CPU cache _anyways_, so negating it and 2's complementing it into >> the CHECKSUM_COMPLETE value for validation is free. >> >> There is no performance advantage whatsoever to use another checksumming >> scheme. > > ok, forget faster/slower argument for a second. > Why is it a bad thing to have HW verifying checksums? Because you have to change the damn hardware and/or firmware for every new protocol. COMPLETE works on _EVERYTHING_ we could ever invent.