From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: [PATCH net-next 1/8] rtnetlink: Do not generate notifications for MTU events Date: Sat, 8 Apr 2017 14:13:55 -0400 Message-ID: <63e0a6c1-ec09-4f04-7e41-edd0adf871b2@cumulusnetworks.com> References: <1491600340-8359-1-git-send-email-dsa@cumulusnetworks.com> <1491600340-8359-2-git-send-email-dsa@cumulusnetworks.com> <58E92699.6090909@cumulusnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, vyasevic@redhat.com, davem@davemloft.net To: Roopa Prabhu Return-path: Received: from mail-io0-f178.google.com ([209.85.223.178]:32880 "EHLO mail-io0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751863AbdDHSN5 (ORCPT ); Sat, 8 Apr 2017 14:13:57 -0400 Received: by mail-io0-f178.google.com with SMTP id t68so31579942iof.0 for ; Sat, 08 Apr 2017 11:13:57 -0700 (PDT) In-Reply-To: <58E92699.6090909@cumulusnetworks.com> Sender: netdev-owner@vger.kernel.org List-ID: On 4/8/17 2:06 PM, Roopa Prabhu wrote: > On 4/7/17, 2:25 PM, David Ahern wrote: >> Changing MTU on a link currently causes 3 messages to be sent to userspace: >> >> [LINK]11: dummy1: mtu 1490 qdisc noqueue state UNKNOWN group default event PRE_CHANGE_MTU >> link/ether f2:52:5c:6d:21:f3 brd ff:ff:ff:ff:ff:ff >> >> [LINK]11: dummy1: mtu 1500 qdisc noqueue state UNKNOWN group default event CHANGE_MTU >> link/ether f2:52:5c:6d:21:f3 brd ff:ff:ff:ff:ff:ff >> >> [LINK]11: dummy1: mtu 1500 qdisc noqueue state UNKNOWN group default >> link/ether f2:52:5c:6d:21:f3 brd ff:ff:ff:ff:ff:ff >> >> Remove the PRE_CHANGE_MTU and CHANGE_MTU messages. >> >> > > This change is good... multiple notifications for the same event does not help in large scale links setups. However, this > reverts what vlad was trying to do with his patchset. Vlad's patch-set relies on the rtnl notifications generated from > notifiers (rtnetlink_event) to add specific event (IFLA_EVENT) in notifications. > > The third notification in your example above is the correct one and is an aggregate notification for a set of changes, but > it cannot really fill in all types of events in the single IFLA_EVENT attribute as it stands today. IFLA_EVENT should be > a bitmask to include all events in this case (i had indicated this in vlads first version). > Agreed. I think it would be best to revert def12888c161 before the UAPI goes out. The change can instead add the IFLA_EVENT as a bitmask mentioned here to note the changes in a setlink. On top of that, remove the notifications for the events I mentioned in this set to reduce the overhead on userspace.