Feature arc represents an ordered list of features/protocols at a given networking layer. It is a high level abstraction to express relationship between rte_graph nodes, as feature nodes, and allow packets steering across these nodes in a simplified manner.
Features (or feature nodes) are nodes which handles partial or complete handling of a protocol in fast path. Like ipv4-rewrite node, which adds rewrite data to an outgoing IPv4 packet. However in above example, outgoing interface(say "eth0") may have outbound IPsec policy enabled, hence packets must be steered from ipv4-rewrite node to outbound-IPsec-policy node. On the other hand, packets routed to another interface (say eth1) must ot be sent to IPsec node, as IPsec feature is disabled on eth1. Feature-arc allows rte_graph applications to manage such constraints easily Feature arc abstraction allows rte_graph based application to 1. Runtime enable/disable features on an index (like interface), so that if a feature is enabled at runtime, only then packets associated with that interface will steer to corresponding feature node. Control plane enables/disables features. Features enabled on one interface may not be enabled on another interface with in a same feature arc. 2. Single feature arc represents a hook point at a network layer in an given direction. Multiple feature arcs can be added in desginated nodes to add various hook points in stack. Likt IPv4-output, IPv4-input, IPv6-output, IPv6-input, ethernet-input, mpls-input, mpls-output etc. 3. Hook custom/out-of-tree nodes to DPDK in-built nodes and allow packet steering from in-built node to custom node without requiring changes to in-built fast path function 4. Express features in a particular sequential order so that packets are steered in an ordered way across nodes in fast path. For eg: if IPsec and IPv4 features are enabled on an ingress interface, packets must be sent to IPsec inbound policy node first and then to ipv4 lookup node. This patch series adds feature arc library in rte_graph and also adds "ipv4-output" feature arc handling in "ipv4-rewrite" node. Changes in v7: - Rebased to latest main for DPDK-25.07 - Added override_index_cb() in RTE_GRAPH_FEATURE_REGISTER() to allow features to take control of "max_index" (passed to rte_graph_feature_arc_create()) - Streamlined fast path APIs to make them more simpler - Added quad_loop in "if_tx_feature" node - Added functional test cases and fixed bugs - Based on feedback from Redhat on v6 patches, it was tried to move feature arc APIs inside rte_graph library (to reduce node burden) but it was adding 4% performance regression for L3fwd usecase. For interested users: https://github.com/nsaxena16/dpdk/pull/2 Changes in v6: - Rebased to latest main for DPDK-25.03 - Added constructor based feature arc/feature registration - Changed design to handle fast path synchronization via RCU mechanism when any feature is enabled or disabled - Added feature arc specific mbuf dynamic field to carry feature data across nodes - Added feature arc example in app/graph - Programming guide and functional test cases in future versions Nitin Saxena (5): graph: add API to override node process function graph: add feature arc abstraction ip4: add ip4 output feature arc app/graph: add custom feature nodes for ip4 output arc test/graph_feature_arc: add functional tests app/graph/commands.list | 6 + app/graph/feature.c | 141 ++ app/graph/feature.h | 13 + app/graph/graph.c | 4 + app/graph/ip4_output_hook.c | 174 ++ app/graph/main.c | 15 +- app/graph/meson.build | 2 + app/graph/module_api.h | 2 + app/test/meson.build | 1 + app/test/test_graph_feature_arc.c | 1374 +++++++++++++++ doc/api/doxy-api-index.md | 2 + doc/guides/rel_notes/release_25_07.rst | 10 + lib/graph/graph_feature_arc.c | 2050 ++++++++++++++++++++++ lib/graph/graph_private.h | 15 + lib/graph/meson.build | 4 +- lib/graph/node.c | 23 + lib/graph/rte_graph_feature_arc.h | 628 +++++++ lib/graph/rte_graph_feature_arc_worker.h | 607 +++++++ lib/node/ethdev_ctrl.c | 8 + lib/node/interface_tx_feature.c | 213 +++ lib/node/interface_tx_feature_priv.h | 33 + lib/node/ip4_rewrite.c | 286 ++- lib/node/meson.build | 1 + lib/node/node_private.h | 1 + lib/node/rte_node_ip4_api.h | 4 + 25 files changed, 5608 insertions(+), 9 deletions(-) create mode 100644 app/graph/feature.c create mode 100644 app/graph/feature.h create mode 100644 app/graph/ip4_output_hook.c create mode 100644 app/test/test_graph_feature_arc.c create mode 100644 lib/graph/graph_feature_arc.c create mode 100644 lib/graph/rte_graph_feature_arc.h create mode 100644 lib/graph/rte_graph_feature_arc_worker.h create mode 100644 lib/node/interface_tx_feature.c create mode 100644 lib/node/interface_tx_feature_priv.h 2.43.0
