Re: [PATCH v3 2/4] net/af_packet: RX/TX unlikely, bulk free, prefetch

Stephen Hemminger
2026-01-29T01:07:24Z

On Wed, 28 Jan 2026 11:10:30 -0800
scott.k.mitch1@gmail.com wrote:

> From: Scott Mitchell <scott.k.mitch1@gmail.com>
>
> - Add rte_prefetch0() to prefetch next frame/mbuf while processing
> current packet, reducing cache miss latency
> - Use rte_pktmbuf_free_bulk() in TX path instead of individual
> rte_pktmbuf_free() calls for better batch efficiency
> - Add unlikely() hints for error paths (oversized packets, VLAN
> insertion failures, sendto errors) to optimize branch prediction
> - Remove unnecessary early nb_pkts == 0 when loop handles this
> and app may never call with 0 frames.
>
> Signed-off-by: Scott Mitchell <scott.k.mitch1@gmail.com>

Drop the prefetch stuff, it doesn't matter.

Original Prefetch Quad/Dual
TX 1.427 Mpps 1.426 Mpps 1.426 Mpps

RX 0.529 Mpps 0.530 Mpps 0.533 Mpps
loss 87.93% 87.98% 88.0%