On Wed, 4 Mar 2026 17:03:36 +0100 Larysa Zaremba <[email protected]> wrote:
> Add likely/unlikely markers for better branch prediction. While touching > some functions, cleanup the code a little bit. > > This patch is not supposed to make any logic changes aside from making > total_rx_bytes and total_rx_packets more correlated. > > Reviewed-by: Aleksandr Loktionov <[email protected]> > Reviewed-by: Alexander Lobakin <[email protected]> > Signed-off-by: Larysa Zaremba <[email protected]> > --- > .../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 29 +++++++++---------- > 1 file changed, 14 insertions(+), 15 deletions(-) > > diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c > b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c > index 5a270dd2c7aa..4619f2bea1ab 100644 > --- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c > +++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c > @@ -570,7 +570,7 @@ static void ixgbevf_alloc_rx_buffers(struct ixgbevf_ring > *rx_ring, > u16 ntu = rx_ring->next_to_use; > > /* nothing to do or no valid netdev defined */ > - if (!cleaned_count || !rx_ring->netdev) > + if (unlikely(!cleaned_count || !rx_ring->netdev)) > return; > > rx_desc = IXGBEVF_RX_DESC(rx_ring, ntu); > @@ -586,7 +586,7 @@ static void ixgbevf_alloc_rx_buffers(struct ixgbevf_ring > *rx_ring, > > rx_desc++; > ntu++; > - if (unlikely(ntu == rx_ring->count)) { > + if (unlikely(ntu == fq.count)) { > rx_desc = IXGBEVF_RX_DESC(rx_ring, 0); > ntu = 0; > } > @@ -823,7 +823,7 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector > *q_vector, > > rx_desc = IXGBEVF_RX_DESC(rx_ring, rx_ring->next_to_clean); > size = le16_to_cpu(rx_desc->wb.upper.length); > - if (!size) > + if (unlikely(!size)) > break; > > /* This memory barrier is needed to keep us from reading > @@ -855,7 +855,7 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector > *q_vector, > } > > /* exit if we failed to retrieve a buffer */ > - if (!xdp_res && !skb) { > + if (unlikely(!xdp_res && !skb)) { I'd check that generates something sensible. Using unlikely on multi-term conditionals doesn't always do something sensible. David > rx_ring->rx_stats.alloc_rx_buff_failed++; > break; > } > @@ -867,21 +867,19 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector > *q_vector, > continue; > > /* verify the packet layout is correct */ > - if (xdp_res || ixgbevf_cleanup_headers(rx_ring, rx_desc, skb)) { > + if (xdp_res || > + unlikely(ixgbevf_cleanup_headers(rx_ring, rx_desc, skb))) { > skb = NULL; > continue; > } > > - /* probably a little skewed due to removing CRC */ > - total_rx_bytes += skb->len; > - > /* Workaround hardware that can't do proper VEPA multicast > * source pruning. > */ > - if ((skb->pkt_type == PACKET_BROADCAST || > - skb->pkt_type == PACKET_MULTICAST) && > - ether_addr_equal(rx_ring->netdev->dev_addr, > - eth_hdr(skb)->h_source)) { > + if (unlikely((skb->pkt_type == PACKET_BROADCAST || > + skb->pkt_type == PACKET_MULTICAST) && > + ether_addr_equal(rx_ring->netdev->dev_addr, > + eth_hdr(skb)->h_source))) { > dev_kfree_skb_irq(skb); > continue; > } > @@ -889,13 +887,14 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector > *q_vector, > /* populate checksum, VLAN, and protocol */ > ixgbevf_process_skb_fields(rx_ring, rx_desc, skb); > > + /* probably a little skewed due to removing CRC */ > + total_rx_bytes += skb->len; > + total_rx_packets++; > + > ixgbevf_rx_skb(q_vector, skb); > > /* reset skb pointer */ > skb = NULL; > - > - /* update budget accounting */ > - total_rx_packets++; > } > > /* place incomplete frames back on ring for completion */
