From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roopa Prabhu Subject: Re: [PATCH net-next v2] ipv4: fib: Replay events when registering FIB notifier Date: Wed, 02 Nov 2016 07:35:03 -0700 Message-ID: <5819F997.2000808@cumulusnetworks.com> References: <1477948427-9189-1-git-send-email-idosch@idosch.org> <1477949046.7065.320.camel@edumazet-glaptop3.roam.corp.google.com> <20161031225737.7nfoy4ka3ydzhptq@splinter> <1478009999.7065.334.camel@edumazet-glaptop3.roam.corp.google.com> <5818B146.20209@cumulusnetworks.com> <20161101170345.pq2ewecw35mrurkp@splinter> <58194BD6.5040406@cumulusnetworks.com> <20161102072032.GA1713@nanopsycho.orion> <20161102134845.GI1713@nanopsycho.orion> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Ido Schimmel , Eric Dumazet , "netdev@vger.kernel.org" , "davem@davemloft.net" , Jiri Pirko , mlxsw , David Ahern , Nikolay Aleksandrov , Andy Gospodarek , Vivien Didelot , Andrew Lunn , Florian Fainelli , alexander.h.duyck@intel.com, Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , Ido Schimmel To: Jiri Pirko Return-path: Received: from mail-pf0-f174.google.com ([209.85.192.174]:33539 "EHLO mail-pf0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750846AbcKBOfH (ORCPT ); Wed, 2 Nov 2016 10:35:07 -0400 Received: by mail-pf0-f174.google.com with SMTP id d2so13174846pfd.0 for ; Wed, 02 Nov 2016 07:35:06 -0700 (PDT) In-Reply-To: <20161102134845.GI1713@nanopsycho.orion> Sender: netdev-owner@vger.kernel.org List-ID: On 11/2/16, 6:48 AM, Jiri Pirko wrote: > Wed, Nov 02, 2016 at 02:29:40PM CET, roopa@cumulusnetworks.com wrote: >> On Wed, Nov 2, 2016 at 12:20 AM, Jiri Pirko wrote: >>> Wed, Nov 02, 2016 at 03:13:42AM CET, roopa@cumulusnetworks.com wrote: >> [snip] >> >>>> I understand..but, if you are adding some core infrastructure for switchdev ..it cannot be >>>> based on the number of simple use-cases or data you have today. >>>> >>>> I won't be surprised if tomorrow other switch drivers have a case where they need to >>>> reset the hw routing table state and reprogram all routes again. Re-registering the notifier to just >>>> get the routing state of the kernel will not scale. For the long term, since the driver does not maintain a cache, >>> Driver (mlxsw, rocker) maintain a cache. So I'm not sure why you say >>> otherwise. >>> >>> >>>> a pull api with efficient use of rtnl will be useful for other such cases as well. >>> How do you imagine this "pull API" should look like? >> >> Just like you already have added fib notifiers to parallel fib netlink >> notifications, the pull API is a parallel to 'netlink dump'. >> Is my imagination too wild ? :) > Perhaps I'm slow, but I don't understand what you mean. >>>> >>>> If you don't want to get to the complexity of a new api right away because of the >>>> simple case of management interface routes you have, Can your driver register the notifier early ? >>>> (I am sure you have probably already thought about this) >>> Register early? What it would resolve? I must be missing something. We >>> register as early as possible. But the thing is, we cannot register >>> in a past. And that is what this patch resolves. >> sure, you must be having a valid problem then. I was just curious why >> your driver is not up and initialized before any of the addresses or >> routes get configured in the system (even on a management port). Ours > If you unload the module and load it again for example. This is a valid > usecase. I see, so you are optimizing for this use case. sure it is a valid use-case but a narrow one compared to the rtnl overhead the api may bring (note that i am not saying you should not solve it). > > >> does. But i agree there can be races and you cannot always guarantee >> (I was just responding to ido's comment about adding complexity for a >> small problem he has to solve for management routes). Our driver does >> a pull before it starts. This helps when we want to reset the hardware >> routing table state too. > Can you point me to you driver in the tree? I would like to see how you > do "the pull". :), you know all this... but, if i must explicitly say it, yes, we don't have a driver in the tree and we don't own the hardware. My analogy here is of a netlink dump that we use heavily for the same scale that you will probably deploy. i do give you full credit for the hardware and the driver and switchdev support and all that!. > >> >> But, my point was, when you are defining an API, you cannot quantify >> the 'past' to be just the very 'close past' or 'the past is just the >> management routes that were added' . Tomorrow the 'past' can be the >> full routing table if you need to reset the hardware state. > Sure. This pull api was a suggestion for an efficient use of rtnl ...similar to how the netlink routing dump handles it. If you cannot imagine an api like that..., sure, your call.