On 11/2/16, 6:48 AM, Jiri Pirko wrote: > Wed, Nov 02, 2016 at 02:29:40PM CET, ro...@cumulusnetworks.com wrote: >> On Wed, Nov 2, 2016 at 12:20 AM, Jiri Pirko <j...@resnulli.us> wrote: >>> Wed, Nov 02, 2016 at 03:13:42AM CET, ro...@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.
