net_sched: sch_fq: add the ability to offload pacing

Some network devices have the ability to offload EDT (Earliest Departure Time) which is the model used for TCP pacing and FQ packet scheduler. Some of them implement the timing wheel mechanism described in https://saeed.github.io/files/carousel-sigcomm17.pdf with an associated 'timing wheel horizon'. This patchs adds to FQ packet scheduler TCA_FQ_OFFLOAD_HORIZON attribute. Its value is capped by the device max_pacing_offload_horizon, added in the prior patch. It allows FQ to let packets within pacing offload horizon to be delivered to the device, which will handle the needed delay without host involvement.

Jeffrey Ji committed 2 years ago

Commit f26080d1 parent f858cc92 files · +29 −6Browse files

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include/uapi/linux/pkt_sched.h+2−0

@@ -836,6 +836,8 @@ enum { · 835 unmodified lines
836	836
837	837	TCA_FQ_WEIGHTS, /* Weights for each band */
838	838
	839	+ TCA_FQ_OFFLOAD_HORIZON, /* dequeue paced packets within this horizon immediately (us units) */
	840	+
839	841	__TCA_FQ_MAX
840	842	};
841	843