Supporting datapath hash allows user to set up rules that provide load balancing of traffic across multiple vports and for ECMP path selection while keeping the number of rule at minimum.
Instead of matching on exact flow spec, which requires a rule per flow, user can define rules based on hashing on the packet headers and distribute the flows to different buckets. The number of rules in this case will be constant and equal to the number of buckets. The datapath hash functionality is achieved in two steps - performing the hash action and then matching on the result, as part of the packet's classification. The api allows user to define a filter with a tc hash action where the hash function can be standard asymetric hashing that Linux offers or alternatively user can provide a bpf program that performs hash calculation on a packet. Usage is as follows: $ tc filter add dev ens1f0_0 ingress \ prio 1 chain 0 proto ip \ flower ip_proto tcp \ action hash bpf object-file <file> \ action goto chain 2 $ tc filter add dev ens1f0_0 ingress \ prio 1 chain 0 proto ip \ flower ip_proto udp \ action hash bpf asym_l4 basis <basis> \ action goto chain 2 $ tc filter add dev ens1f0_0 ingress \ prio 1 chain 2 proto ip \ flower hash 0x0/0xf \ action mirred egress redirect dev ens1f0_1 $ tc filter add dev ens1f0_0 ingress \ prio 1 chain 2 proto ip \ flower hash 0x1/0xf \ action mirred egress redirect dev ens1f0_2 Ariel Levkovich (3): net/sched: Introduce action hash net/flow_dissector: add packet hash dissection net/sched: cls_flower: Add hash info to flow classification include/linux/skbuff.h | 4 + include/net/act_api.h | 2 + include/net/flow_dissector.h | 9 + include/net/tc_act/tc_hash.h | 22 ++ include/uapi/linux/pkt_cls.h | 4 + include/uapi/linux/tc_act/tc_hash.h | 32 +++ net/core/flow_dissector.c | 17 ++ net/sched/Kconfig | 11 + net/sched/Makefile | 1 + net/sched/act_hash.c | 389 ++++++++++++++++++++++++++++ net/sched/cls_api.c | 1 + net/sched/cls_flower.c | 16 ++ 12 files changed, 508 insertions(+) create mode 100644 include/net/tc_act/tc_hash.h create mode 100644 include/uapi/linux/tc_act/tc_hash.h create mode 100644 net/sched/act_hash.c -- 2.25.2
