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| -rw-r--r-- | docs/configuration/interfaces/ethernet.rst | 105 |
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diff --git a/docs/configuration/interfaces/ethernet.rst b/docs/configuration/interfaces/ethernet.rst index 7288d9d2..8d31fc70 100644 --- a/docs/configuration/interfaces/ethernet.rst +++ b/docs/configuration/interfaces/ethernet.rst @@ -71,6 +71,111 @@ Ethernet options The supported values for a specific interface can be obtained with: `ethtool -g <interface>` +Interrupt Coalescing +---------- + +Interrupt coalescing is a mechanism that reduces CPU interrupt load by bundling +multiple packets into a single interrupt event instead of interrupting +the CPU for every packet arrival or transmission. + +.. note:: Not all network drivers or virtual interfaces support all + coalescing parameters. Use ``ethtool --show-coalesce <interface>`` + to verify which settings are supported by your hardware and driver. + +**Basic adaptive coalescing** + +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing adaptive-rx +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing adaptive-tx + + Enable adaptive interrupt coalescing. The NIC automatically tunes RX/TX + interrupt pacing based on traffic patterns to reduce CPU utilization + during high throughput while preserving latency at low packet rates. + +**Basic interrupt delay** + +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing rx-usecs <0-16384> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing tx-usecs <0-16384> + + Set the delay in microseconds before generating an RX/TX interrupt after + receiving or transmitting a packet. Lower values reduce latency; higher + values reduce CPU load. + +**Interrupt frame thresholds** + +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing rx-frames <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing tx-frames <number> + + Generate an RX/TX interrupt only after the specified number of packets + have been received or transmitted. + +**IRQ-specific coalescing** + +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing rx-usecs-irq <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing rx-frames-irq <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing tx-usecs-irq <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing tx-frames-irq <number> + + Control interrupt coalescing parameters while the driver is already + servicing an interrupt (IRQ context). These settings allow finer tuning + of interrupt behavior under sustained load. + +**Adaptive rate thresholds** + +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing pkt-rate-low <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing pkt-rate-high <number> + + Define packet-rate thresholds (packets per second) used by adaptive + coalescing to switch between low-rate and high-rate interrupt coalescing + profiles. + +**Low-rate adaptive parameters** + +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing rx-usecs-low <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing rx-frame-low <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing tx-usecs-low <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing tx-frame-low <number> + + Interrupt coalescing parameters applied when the packet rate is below + ``pkt-rate-low``. Typically optimized for lower latency. + +**High-rate adaptive parameters** + +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing rx-usecs-high <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing rx-frame-high <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing tx-usecs-high <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing tx-frame-high <number> + + Interrupt coalescing parameters applied when the packet rate exceeds + ``pkt-rate-high``. Typically optimized for maximum throughput and + reduced CPU utilization. + +**Statistics and sampling** + +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing stats-block-usecs <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing sample-interval <number> + + Control how frequently coalescing statistics are updated and how often + the NIC samples traffic rates for adaptive coalescing decisions. + +**Completion queue (CQE) mode** + +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing cqe-mode-rx +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing cqe-mode-tx + + Enable RX/TX Completion Queue Entry (CQE) mode, if supported by the + driver. CQE mode can improve performance on high-speed NICs by + optimizing completion handling. + +**Transmit aggregation** + +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing tx-aggr-max-bytes <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing tx-aggr-max-frames <number> +.. cfgcmd:: set interfaces ethernet <interface> interrupt-coalescing tx-aggr-time-usecs <number> + + Control transmit packet aggregation. Packets may be buffered and sent + together until one of the configured limits (bytes, frames, or time) + is reached, reducing interrupt and DMA overhead. + Offloading ---------- |