From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Graf Subject: Re: [PATCH v5 net-next] MPLS: Use mpls_features to activate software MPLS GSO segmentation Date: Wed, 4 Jun 2014 11:13:36 +0100 Message-ID: <20140604101336.GE17695@casper.infradead.org> References: <1401839597-8961-1-git-send-email-horms@verge.net.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , netdev@vger.kernel.org, Jesse Gross , YAMAMOTO Takashi , dev@openvswitch.org To: Simon Horman Return-path: Received: from casper.infradead.org ([85.118.1.10]:45912 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752133AbaFDKNk (ORCPT ); Wed, 4 Jun 2014 06:13:40 -0400 Content-Disposition: inline In-Reply-To: <1401839597-8961-1-git-send-email-horms@verge.net.au> Sender: netdev-owner@vger.kernel.org List-ID: On 06/04/14 at 08:53am, Simon Horman wrote: > If an MPLS packet requires segmentation then use mpls_features > to determine if the software implementation should be used. > > As no driver advertises MPLS GSO segmentation this will always be > the case. > > I had not noticed that this was necessary before as software MPLS GSO > segmentation was already being used in my test environment. I believe that > the reason for that is the skbs in question always had fragments and the > driver I used does not advertise NETIF_F_FRAGLIST (which seems to be the > case for most drivers). Thus software segmentation was activated by > skb_gso_ok(). > > This introduces the overhead of an extra call to skb_network_protocol() > in the case where where CONFIG_NET_MPLS_GSO is set and > skb->ip_summed == CHECKSUM_NONE. > > Thanks to Jesse Gross for prompting me to investigate this. > > Signed-off-by: Simon Horman > Acked-by: YAMAMOTO Takashi LGTM Acked-by: Thomas Graf