From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nikolay Aleksandrov Subject: Re: [PATCH net] bonding: fix arp monitoring with vlan slaves Date: Sat, 03 Aug 2013 02:21:14 +0200 Message-ID: <51FC4CFA.8010706@redhat.com> References: <1375461665-4186-1-git-send-email-nikolay@redhat.com> <20130802.153212.1340051334413929810.davem@davemloft.net> <1375485466.4457.4.camel@edumazet-glaptop> <51FC40E5.6050809@redhat.com> <1375488223.4457.16.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org, andy@greyhouse.net, fubar@us.ibm.com To: Eric Dumazet Return-path: Received: from mx1.redhat.com ([209.132.183.28]:28227 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752178Ab3HCAVW (ORCPT ); Fri, 2 Aug 2013 20:21:22 -0400 In-Reply-To: <1375488223.4457.16.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: On 08/03/2013 02:03 AM, Eric Dumazet wrote: > On Sat, 2013-08-03 at 01:29 +0200, Nikolay Aleksandrov wrote: > >> I knew it was because of the LLTX, but I was wondering about the possible >> reasons for the xmit_lock_owner check. >> So basically the arp monitoring (or any dev_trans_start code) won't work >> with LLTX devices because they don't get their trans_start updated (not the >> txq trans_start nor the dev->trans_start), is this correct ? > > Nope : LLTX devices are supposed to update their own dev->trans_start > I added for these case a special comment as in : > > drivers/net/ethernet/atheros/atl1e/atl1e_main.c:1883: netdev->trans_start = jiffies; /* NETIF_F_LLTX driver :( */ > Ah, didn't know about that, so there could be an LLTX device with proper trans_start if it updates it itself. Fair enough. > trans_start is a txq property, and vlan devices have a single txq. > > Updating the vlandev->trans_start or the vlantxq->trans_start would be a > performance killer on MQ ethernet. > Yeah, that part I got, that's why I said it explains a lot for me earlier :-) > And frankly, as this trans_start is really seldom queried, it makes no > sense to set it on fast path on the vlan device, if its properly done on > the real device anyway. > >> But what if the txqs get bound to a particular CPU, then the txq >> trans_start is okay to be updated I suppose. > > Not sure what you are saying. vlan xmit can be called from any cpus. > Never mind, I didn't notice that the 8021q dev has a single txq as you said. Thanks for taking the time to explain all this.