This patchset adds support to do GRO/GSO by chaining packets of the same flow at the SKB frag_list pointer. This avoids the overhead to merge payloads into one big packet, and on the other end, if GSO is needed it avoids the overhead of splitting the big packet back to the native form.
Patch 1 Enables UDP GRO by default. Patch 2 adds netdev feature flags to enable listifyed GRO, this implements one of the configuration options discussed at netconf 2019. Patch 3 adds a netdev software feature set that defaults to off and assigns the new listifyed GRO feature flag to it. Patch 4 adds the core infrastructure to do fraglist GRO/GSO. Patch 5 enables UDP to use fraglist GRO/GSO if configured and no GRO supported socket is found. I have only meaningful forwarding performance measurements. I did some tests for the local receive path with netperf and iperf, but in this case the sender that generates the packets is the bottleneck. So the benchmarks are not that meaningful for the receive path. Paolo Abeni did some benchmarks of the local receive path for the v2 version of this pachset, results can be found here: https://www.spinics.net/lists/netdev/msg551158.html I used my IPsec forwarding test setup for the performance measurements: ------------ ------------ -->| router 1 |-------->| router 2 |-- | ------------ ------------ | | | | -------------------- | --------|Spirent Testcenter|<---------- -------------------- net-next (September 7th): Single stream UDP frame size 1460 Bytes: 1.161.000 fps (13.5 Gbps). ---------------------------------------------------------------------- net-next (September 7th) + standard UDP GRO/GSO: Single stream UDP frame size 1460 Bytes: 1.801.000 fps (21 Gbps). ---------------------------------------------------------------------- net-next (September 7th) + fraglist UDP GRO/GSO: Single stream UDP frame size 1460 Bytes: 2.860.000 fps (33.4 Gbps). ----------------------------------------------------------------------- Changes from v1: - Add IPv6 support. - Split patchset to enable UDP GRO by default before adding fraglist GRO support. - Mark fraglist GRO packets as CHECKSUM_NONE. - Take a refcount on the first segment skb when doing fraglist segmentation. With this we can use the same error handling path as with standard segmentation. Changes from v2: - Add a netdev feature flag to configure listifyed GRO. - Fix UDP GRO enabling for IPv6. - Fix a rcu_read_lock() imbalance. - Fix error path in skb_segment_list(). Changes from v3: - Rename NETIF_F_GRO_LIST to NETIF_F_GRO_FRAGLIST and add NETIF_F_GSO_FRAGLIST. - Move introduction of SKB_GSO_FRAGLIST to patch 2. - Use udpv6_encap_needed_key instead of udp_encap_needed_key in IPv6. - Move some missplaced code from patch 5 to patch 1 where it belongs to.
