From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Dichtel Subject: Re: [PATCH net 1/2] geneve, vxlan: Don't check skb_dst() twice Date: Mon, 15 Oct 2018 14:24:24 +0200 Message-ID: <3bb05500-d304-96b1-46cc-af6da2c49bc0@6wind.com> References: <61596775-4b5f-884a-7a0d-d8c134bb7e8a@6wind.com> <20181015130830.1c177301@redhat.com> Reply-To: nicolas.dichtel@6wind.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: "David S. Miller" , Xin Long , Sabrina Dubroca , netdev@vger.kernel.org To: Stefano Brivio Return-path: Received: from mail-wr1-f67.google.com ([209.85.221.67]:45082 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726400AbeJOUJc (ORCPT ); Mon, 15 Oct 2018 16:09:32 -0400 Received: by mail-wr1-f67.google.com with SMTP id q5-v6so21089123wrw.12 for ; Mon, 15 Oct 2018 05:24:27 -0700 (PDT) In-Reply-To: <20181015130830.1c177301@redhat.com> Content-Language: fr Sender: netdev-owner@vger.kernel.org List-ID: Le 15/10/2018 à 13:08, Stefano Brivio a écrit : > On Mon, 15 Oct 2018 12:19:41 +0200 > Nicolas Dichtel wrote: > >> Le 12/10/2018 à 23:53, Stefano Brivio a écrit : >>> Commit f15ca723c1eb ("net: don't call update_pmtu unconditionally") avoids >>> that we try updating PMTU for a non-existent destination, but didn't clean >>> up cases where the check was already explicit. Drop those redundant checks. >> Yes, I leave them to avoid calculating the new mtu value when not needed. We are >> in the xmit path. > > Before 2/2 of this series, though, we call skb_dst_update_pmtu() (and > in turn dst->ops->update_pmtu()) for *every* packet with a dst, which Not if dst is of type md_dst_ops. > I'd dare saying is by far the most common case. Besides, 2/2 needs > anyway to calculate the MTU to fix a bug. > > So I think this is a vast improvement overall. Fair point.