README
¶
taprio-stream
TSN (Time-Sensitive Networking) stream scheduling for DDS topics using tsn.StreamConfig and tsn.TAPRIOConfig.
Pattern: bounded-latency publishing — a TSN stream descriptor binds a DDS topic to a TAPRIO gate control schedule. Published frames carry a computed SO_TXTIME transmit timestamp aligned to the TSN interval.
Run
go run .
What it shows
| Concept | Where |
|---|---|
tsn.StreamConfig |
per-topic TSN stream descriptors (VID, PCP, DSCP, interval, offset) |
tsn.TAPRIOFromStreams |
derives a TAPRIO gate control list from stream descriptors |
TAPRIOConfig.TCCommand |
generates a tc(8) command for manual qdisc programming |
TAPRIOConfig.Apply() |
programs the TAPRIO qdisc via RTM_NEWQDISC netlink (Linux only) |
nextTxTime |
computes per-frame SO_TXTIME: next interval boundary + configured offset |
TypedPublisher[T] |
publishes VehicleSpeed structs with embedded transmit timestamp |
TAPRIO on Linux
To actually program the kernel qdisc (requires Linux + CAP_NET_ADMIN):
taprioCfg.Interface = "eth0"
taprioCfg.BaseTime = 0 // kernel picks next cycle boundary
if err := taprioCfg.Apply(); err != nil {
log.Fatal(err)
}
On macOS/Windows, Apply() returns tsn.ErrNotSupported. Use TCCommand to get the equivalent tc(8) shell command and run it manually.
Expected output
Stream: vehicle/speed interval=1ms offset=0s PCP=5 DSCP=46
TAPRIO schedule: cycle=3ms entries=2
entry[0]: gate_mask=0x20 interval=1ms
entry[1]: gate_mask=0x10 interval=2ms
tc command (for use on Linux with CAP_NET_ADMIN):
tc qdisc replace dev eth0 parent root handle 100 taprio ...
Publishing 8 frames at 1ms intervals:
[send] kph=80.0 sched_tx=1749413400001000000ns
[recv] kph=80.0 sched_tx=1749413400001000000ns
...
Documentation
¶
Overview ¶
taprio-stream demonstrates how to configure a TSN stream for bounded-latency DDS publishing using tsn.StreamConfig and tsn.TAPRIOConfig.
The example:
- Loads a TSN stream config describing the "vehicle/speed" topic.
- Derives a TAPRIO gate control list from the stream descriptors.
- Prints the tc(8) command that would program the schedule on a real NIC (requires Linux + CAP_NET_ADMIN for the actual Apply call).
- Simulates SO_TXTIME-aligned publishing: computes the per-frame transmit timestamp based on the TSN interval and offset, then publishes 8 frames at that cadence using the in-process mock transport.
Run with:
go run .
Source Files
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