On Tue, Dec 5, 2017 at 10:10 AM, Marcelo Ricardo Leitner <marcelo.leit...@gmail.com> wrote: > On Mon, Dec 04, 2017 at 04:07:15PM -0800, Michael Chan wrote: >> As already pointed out, GRO_HW is a subset of GRO. Packets that >> cannot be aggregated in hardware (due to hardware resource limitations >> or protocol types that it doesn't handle) can just be passed to the >> stack for GRO aggregation. > > How would the parameters/limits work in this case? I mean, currently > we have the default weight of 64 packets per napi poll cycle, the > budget of 300 per cycle and also the time constrain, > net.core.netdev_budget_usecs.
Good point. Currently, it is no different than LRO. Each aggregated packet is counted as 1. With LRO, you don't necessarily know many packets were merged. With GRO_HW, we know and it's possible to count the original packets towards the NAPI budget. > > With GRO_HW, this 64 limit may be exceeded. I'm looking at qede code > and it works by couting each completion as 1 rcv_pkts > (qede_fp.c:1318). So if it now gets 64 packets, it's up to 64*MTU > aprox, GRO'ed or not. But with GRO_HW, seems it may be much more than > that and which may not be fair with other interfaces in the system. > Drivers supporting GRO_HW probably should account for this. Right. We can make this adjustment for GRO_HW in a future patchset. > > And how can one control how much time a packet may spend on NIC queue > waiting to be GRO'ed? Does it use the coalescing parameters for that? > The GRO_HW timer is currently not exposed. It's different from interrupt coalescing. It's possible to make this a tunable parameter in the future.
