> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf
> Of Kohei Enju
> Sent: Saturday, March 7, 2026 7:28 PM
> To: [email protected]; [email protected]
> Cc: Nguyen, Anthony L <[email protected]>; Kitszel,
> Przemyslaw <[email protected]>; Andrew Lunn
> <[email protected]>; David S. Miller <[email protected]>; Eric
> Dumazet <[email protected]>; Jakub Kicinski <[email protected]>; Paolo
> Abeni <[email protected]>; [email protected]; Kohei Enju
> <[email protected]>
> Subject: [Intel-wired-lan] [PATCH iwl-next v1 2/2] igc: enable
> build_skb on the non-XDP small-frame RX path
>
> igc implements igc_build_skb(), but it is currently unused because the
> IGC_RING_FLAG_RX_BUILD_SKB_ENABLED bit is never set. Enable the
> build_skb path when XDP is not active and the configured maximum frame
> size fits within IGC_MAX_FRAME_BUILD_SKB.
>
> In a single-queue small-packet (64-byte) RX microbenchmark on my
> setup, enabling build_skb improved the receive rate from about 3.11
> Mpps to about 3.30 Mpps, while reducing missed packets from about 484
> kpps to about 300 kpps.
>
> Keep the XDP path unchanged for now, since it uses a different RX
> buffer layout based on XDP_PACKET_HEADROOM, and enabling it there
> would need separate validation and buffer layout adjustments.
>
> Signed-off-by: Kohei Enju <[email protected]>
> ---
> drivers/net/ethernet/intel/igc/igc.h | 4 ++++
> drivers/net/ethernet/intel/igc/igc_main.c | 4 ++++
> 2 files changed, 8 insertions(+)
>
> diff --git a/drivers/net/ethernet/intel/igc/igc.h
> b/drivers/net/ethernet/intel/igc/igc.h
> index e66799507f81..acbd2c237667 100644
> --- a/drivers/net/ethernet/intel/igc/igc.h
> +++ b/drivers/net/ethernet/intel/igc/igc.h
> @@ -734,6 +734,10 @@ enum igc_ring_flags_t {
>
> #define ring_uses_build_skb(ring) \
> test_bit(IGC_RING_FLAG_RX_BUILD_SKB_ENABLED, &(ring)->flags)
> +#define set_ring_uses_build_skb(ring) \
> + set_bit(IGC_RING_FLAG_RX_BUILD_SKB_ENABLED, &(ring)->flags)
> #define
> +clear_ring_uses_build_skb(ring) \
> + clear_bit(IGC_RING_FLAG_RX_BUILD_SKB_ENABLED, &(ring)->flags)
>
> static inline unsigned int igc_rx_bufsz(struct igc_ring *ring) {
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
> b/drivers/net/ethernet/intel/igc/igc_main.c
> index 3a4c1ebe4faa..1f3ed1e4db1b 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -474,6 +474,7 @@ static void igc_clean_rx_ring(struct igc_ring
> *ring)
> igc_clean_rx_ring_page_shared(ring);
>
> clear_ring_uses_large_buffer(ring);
> + clear_ring_uses_build_skb(ring);
>
> ring->next_to_alloc = 0;
> ring->next_to_clean = 0;
> @@ -654,6 +655,9 @@ static void igc_configure_rx_ring(struct
> igc_adapter *adapter,
>
> if (igc_xdp_is_enabled(adapter))
> set_ring_uses_large_buffer(ring);
> + else if (!(adapter->flags & IGC_FLAG_RX_LEGACY) &&
> + adapter->max_frame_size <= IGC_MAX_FRAME_BUILD_SKB)
> + set_ring_uses_build_skb(ring);
>
> /* disable the queue */
> wr32(IGC_RXDCTL(reg_idx), 0);
> --
> 2.51.0
Reviewed-by: Aleksandr Loktionov <[email protected]>
