Hi David, > -----Original Message----- > From: David Marchand <david.march...@redhat.com> > Sent: Thursday, June 1, 2023 12:43 PM > Subject: Re: [RFC PATCH] ethdev: advertise flow restore in mbuf > > On Thu, Jun 1, 2023 at 11:31 AM Ori Kam <or...@nvidia.com> wrote: > > > > > > > > > -----Original Message----- > > > From: David Marchand <david.march...@redhat.com> > > > Sent: Thursday, June 1, 2023 11:48 AM > > > > > > On Wed, May 24, 2023 at 8:44 PM David Marchand > > > <david.march...@redhat.com> wrote: > > > > On Wed, May 24, 2023 at 6:00 PM Ori Kam <or...@nvidia.com> wrote: > > > > > > As reported by Ilya [1], unconditionally calling > > > > > > rte_flow_get_restore_info() impacts an application performance for > > > drivers > > > > > > that do not provide this ops. > > > > > > It could also impact processing of packets that require no call to > > > > > > rte_flow_get_restore_info() at all. > > > > > > > > > > > > Advertise in mbuf (via a dynamic flag) whether the driver has more > > > > > > metadata to provide via rte_flow_get_restore_info(). > > > > > > The application can then call it only when required. > > > > > > > > > > > > Link: http://inbox.dpdk.org/dev/5248c2ca-f2a6-3fb0-38b8- > > > > > > 7f659bfa4...@ovn.org/ > > > > > > Signed-off-by: David Marchand <david.march...@redhat.com> > > > > > > --- > > > > > > Note: I did not test this RFC patch yet but I hope we can resume > and > > > > > > maybe conclude on the discussion for the tunnel offloading API. > > > > > > > > > > > > > > > > I think your approach has a good base but what happens if > > > > > it is not relevant for all flows? In this case your solution will not > > > > > work. > > > > > > > > Sorry, I am not following. > > > > Could you develop? > > > > > > I still don't get your comment, could you give an example/usecase > > > where this approach can't work? > > > Thanks. > > > > > I'm think of a use case that some flows have the restore info, while > > other don't for example, we get arp packets or some packets that > > are not tunneled, and we also get tunneled packets. > > > > Or for example PMD supports this flag but the application didn't offload > such a rule yet. > > Again, maybe I missed something, but my proposal is for a *per packet* > report from the driver. > I am not for a global driver capability, if this is what you have in mind. > My bad, per packet solves the issue I was talking about, but it makes it worse. This means that PMD needs to add logic in it's datapath. This may affect all traffic.
> > > > > In those cases application will be slow even if he didn't offload the rules, > > I assume we can say that if application wants to use this he should know > > that other packets will have some performance issues. > > > > From my point of view if application requested the tunnel offload it should > > always check this function. > > With a per packet flag, the application only calls restore_info when > such tunnel offload rules have been requested, and only for packets > that require it. > > > -- > David Marchand
