UCP/UCT/IB: Add per-endpoint traffic class (DSCP) for RC/RoCE (QOS)#11618
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ybenvidia wants to merge 4 commits into
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UCP/UCT/IB: Add per-endpoint traffic class (DSCP) for RC/RoCE (QOS)#11618ybenvidia wants to merge 4 commits into
ybenvidia wants to merge 4 commits into
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Add an optional per-endpoint traffic class programmed onto the RC mlx5 QP, so endpoints can be tagged with a distinct DSCP (RoCEv2) or GRH traffic class (IB) for fabric QoS. - API: ucp_ep_params.ep_traffic_class + UCP_EP_PARAM_FIELD_EP_TRAFFIC_CLASS - UCT: uct_ep_connect_to_ep_params_t.ep_traffic_class + UCT_EP_CONNECT_TO_EP_PARAM_FIELD_EP_TRAFFIC_CLASS - Plumb UCP ep params -> wireup -> rc mlx5 devx QP (primary_address_path.dscp for RoCEv2, .tclass for IB); default behavior unchanged when unset - Sentinels UCP_EP_NO_TCLASS / UCT_EP_NO_TCLASS - Java binding constant
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What
Add an optional per-endpoint traffic class that is programmed onto the
RC mlx5 QP, so different endpoints/flows can be tagged with a different
DSCP (RoCEv2) or GRH traffic class (IB) for fabric QoS/arbitration.
Why
QoS use cases (e.g. prioritizing one UCC team / process-group over another)
need to set a distinct DSCP per set of connections. UCX previously only had
a single iface-wide
UCX_IB_TRAFFIC_CLASS; there was no way to select thetraffic class per endpoint at connect time.
Changes
ucp_ep_params.ep_traffic_classfield, enabled withUCP_EP_PARAM_FIELD_EP_TRAFFIC_CLASS.uct_ep_connect_to_ep_params_t.ep_traffic_classfield, enabledwith
UCT_EP_CONNECT_TO_EP_PARAM_FIELD_EP_TRAFFIC_CLASS.ucp_ep_adjust_params→UCP_EP_FLAG_EP_TRAFFIC_CLASS→wireup (
ucp_wireup_connect_local,ucp_wireup_ep_connect_to_ep_v2) →uct_rc_mlx5_iface_common_devx_connect_qp.primary_address_path.dscp(RoCEv2) orprimary_address_path.tclass(IB, when GRH present). When the field is notset, behavior is unchanged (falls back to the iface default DSCP/tclass).
UCP_EP_NO_TCLASS/UCT_EP_NO_TCLASSfor "not set".Compatibility
Fully opt-in and backward compatible: without the field mask bit, the QP is
programmed exactly as before.
Testing
ucc_perftestwith a per-team traffic class, verified end-to-end:the value set at connect time is written to the QP
primary_address_path.dscp(checked value tracks the input, e.g. 24 → 37).
RDMA sniffer show the configured DSCP in the IP header (DSCP 37 → ToS 0x94).
service connections keep the default.