Re: [PATCH net-next 06/11] net: fec: transmit XDP frames in bulk
From: Frank Li <Frank.li@nxp.com>
Date: 2026-01-13 16:17:14
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bpf, imx, lkml
On Tue, Jan 13, 2026 at 11:29:34AM +0800, Wei Fang wrote:
Currently, the driver writes the ENET_TDAR register for every XDP frame to trigger transmit start. Frequent MMIO writes consume more CPU cycles and may reduce XDP TX performance, so transmit XDP frames in bulk. Signed-off-by: Wei Fang <wei.fang@nxp.com> ---
Did you test light loading case? Any unexpected latency happen? sometime missing trigger is hard to find when heavy loading. Frank
quoted hunk ↗ jump to hunk
drivers/net/ethernet/freescale/fec_main.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index 0b114a68cd8e..f3e93598a27c 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c@@ -1994,6 +1994,8 @@ static int fec_enet_rx_queue_xdp(struct fec_enet_private *fep, int queue, rxq->stats[RX_XDP_TX_ERRORS]++; fec_xdp_drop(rxq, &xdp, sync); trace_xdp_exception(ndev, prog, XDP_TX); + } else { + xdp_res |= FEC_ENET_XDP_TX; } break; default:@@ -2043,6 +2045,10 @@ static int fec_enet_rx_queue_xdp(struct fec_enet_private *fep, int queue, if (xdp_res & FEC_ENET_XDP_REDIR) xdp_do_flush(); + if (xdp_res & FEC_ENET_XDP_TX) + /* Trigger transmission start */ + fec_txq_trigger_xmit(fep, fep->tx_queue[queue]); + return pkt_received; }@@ -4033,9 +4039,6 @@ static int fec_enet_txq_xmit_frame(struct fec_enet_private *fep, txq->bd.cur = bdp; - /* Trigger transmission start */ - fec_txq_trigger_xmit(fep, txq); - return 0; }@@ -4087,6 +4090,9 @@ static int fec_enet_xdp_xmit(struct net_device *dev, sent_frames++; } + if (sent_frames) + fec_txq_trigger_xmit(fep, txq); + __netif_tx_unlock(nq); return sent_frames; --2.34.1