On Wed, 27 Jun 2018 09:50:17 +0200, Jiri Pirko wrote: > Tue, Jun 26, 2018 at 11:18:58PM CEST, jakub.kicin...@netronome.com wrote: > >On Tue, 26 Jun 2018 09:12:17 +0200, Jiri Pirko wrote: > >> Tue, Jun 26, 2018 at 09:00:45AM CEST, jakub.kicin...@netronome.com wrote: > >> >On Mon, Jun 25, 2018 at 11:43 PM, Jiri Pirko <j...@resnulli.us> wrote: > >> >> Tue, Jun 26, 2018 at 06:58:50AM CEST, jakub.kicin...@netronome.com > >> >> wrote: > >> >>>On Mon, 25 Jun 2018 23:01:39 +0200, Jiri Pirko wrote: > >> >>>> From: Jiri Pirko <j...@mellanox.com> > >> >>>> > >> >>>> For the TC clsact offload these days, some of HW drivers need > >> >>>> to hold a magic ball. The reason is, with the first inserted rule > >> >>>> inside > >> >>>> HW they need to guess what fields will be used for the matching. If > >> >>>> later on this guess proves to be wrong and user adds a filter with a > >> >>>> different field to match, there's a problem. Mlxsw resolves it now > >> >>>> with > >> >>>> couple of patterns. Those try to cover as many match fields as > >> >>>> possible. > >> >>>> This aproach is far from optimal, both performance-wise and > >> >>>> scale-wise. > >> >>>> Also, there is a combination of filters that in certain order won't > >> >>>> succeed. > >> >>>> > >> >>>> Most of the time, when user inserts filters in chain, he knows right > >> >>>> away > >> >>>> how the filters are going to look like - what type and option will > >> >>>> they > >> >>>> have. For example, he knows that he will only insert filters of type > >> >>>> flower matching destination IP address. He can specify a template that > >> >>>> would cover all the filters in the chain. > >> >>> > >> >>>Perhaps it's lack of sleep, but this paragraph threw me a little off > >> >>>the track. IIUC the goal of this set is to provide a way to inform the > >> >>>HW about expected matches before any rule is programmed into the HW. > >> >>>Not before any rule is added to a particular chain. One can just use > >> >>>the first rule in the chain to make a guess about the chain, but thanks > >> >>>to this set user can configure *all* chains before any rules are added. > >> >>> > >> >> > >> >> The template is per-chain. User can use template for chain x and > >> >> not-use it for chain y. Up to him. > >> > > >> >Makes sense. > >> > > >> >I can't help but wonder if it'd be better to associate the > >> >constraints/rules with chains instead of creating a new "template" > >> >object. It seems more natural to create a chain with specific > >> >constraints in place than add and delete template of which there can > >> >be at most one to a chain... Perhaps that's more about the user space > >> >tc command line. Anyway, not a strong objection, just a thought. > >> > >> Hmm. I don't think it is good idea. User should see the template in a > >> "show" command per chain. We would have to have 2 show commands, one to > >> list the template objects and one to list templates per chains. It makes > >> things more complicated for no good reason. I think that this simple > >> chain-lock is easier and serves the purpose. > > > >Hm, I think the dump is fine, what I was thinking about was: > > > ># tc chain add dev dummy0 ingress chain_index 22 \ > > ^^^^^ > > template proto ip \ > > ^^^^^^^^ > > flower dst_mac 00:00:00:00:00:00/00:00:00:00:FF:FF > > Okay, I got it. I see 2 issues. > 1) user might expect to add a chain without the template. But that does > not make sense really. Chains are created/deleted implicitly > according to refcount. > 2) there is not chain object like this available to user. Adding it just > for template looks odd. Also, the "filter" and "template" are very > much alike. They both are added to a chain, they both implicitly > create chain if it does not exist, etc.
Yeah, that part makes is tricky :/ > if you don't like "tc filter template add dev dummy0 ingress", how > about: > "tc template add dev dummy0 ingress ..." > "tc template add dev dummy0 ingress chain 22 ..." > that makes more sense I think. Mmm.. how about: tc chaintemplate add dev dummy0 ingress... or tc restrictedchain add dev dummy0 ingress chain_index XX template ...
