Multi-core network packet steering: Difference between revisions

Revision as of 09:02, 11 July 2025

Revision as of 12:29, 11 July 2025

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[[File:ARFS architecture.png|upright=1.7|thumb|Simple view of the accelerated receive flow steering architecture]]

Accelerated Receive Flow Steering (aRFS) is another hardware supported technique, born with the idea of leveraging [[Locality of reference|cache locality]] to improve performances by routing incoming packet flows to specific cores.

Differently from RSS which is a fully hardware independent hardware implementation, aRFS needs to interface with the software (the [[Kernel (operating system)|kernel]]) to properly function.<ref>{{Cite web|title=aRFS kernel linux docs|url=https://www.kernel.org/doc/html/v5.1/networking/scaling.html#accelerated-rfs|access-date=2025-07-08|website=kernel.org|publisher=The Linux Kernel documentation|language=en-US}}</ref><br>

RSS simply load balance incoming traffic across the cores; however if a packet flow is directed to the ''core i'' (as a result of the hash function) while the application needing the received packet is running on ''core j'', many cache misses could be avoided by simply forcing ''i=j'', so that packets are received exactly where they are needed and consumed.<ref name="aRFS by nvidea" /><br>

To do this aRFS doesn't forward packets directly from the result of the hash function, but using a configurable routing table (which can be filled and updated for instance by the [[Scheduling (computing)|scheduler]] through an [[API]]) packet flows can be steered to the specific consuming core.<ref name="aRFS by nvidea" /><ref name="aRFS by redhat" />