diff options
| -rw-r--r-- | target/linux/bcm4908/patches-5.10/079-v6.2-0001-net-broadcom-bcm4908_enet-use-build_skb.patch | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/target/linux/bcm4908/patches-5.10/079-v6.2-0001-net-broadcom-bcm4908_enet-use-build_skb.patch b/target/linux/bcm4908/patches-5.10/079-v6.2-0001-net-broadcom-bcm4908_enet-use-build_skb.patch new file mode 100644 index 0000000000..1a3dc62d44 --- /dev/null +++ b/target/linux/bcm4908/patches-5.10/079-v6.2-0001-net-broadcom-bcm4908_enet-use-build_skb.patch @@ -0,0 +1,152 @@ +From 3a1cc23a75abcd9cea585eb84846507363d58397 Mon Sep 17 00:00:00 2001 +From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl> +Date: Tue, 25 Oct 2022 15:22:45 +0200 +Subject: [PATCH] net: broadcom: bcm4908_enet: use build_skb() +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +RX code can be more efficient with the build_skb(). Allocating actual +SKB around eth packet buffer - right before passing it up - results in +a better cache usage. + +Without RPS (echo 0 > rps_cpus) BCM4908 NAT masq performance "jumps" +between two speeds: ~900 Mbps and 940 Mbps (it's a 4 CPUs SoC). This +change bumps the lower speed from 905 Mb/s to 918 Mb/s (tested using +single stream iperf 2.0.5 traffic). + +There are more optimizations to consider. One obvious to try is GRO +however as BCM4908 doesn't do hw csum is may actually lower performance. +Sometimes. Some early testing: + +┌─────────────────────────────────┬─────────────────────┬────────────────────┐ +│ │ netif_receive_skb() │ napi_gro_receive() │ +├─────────────────────────────────┼─────────────────────┼────────────────────┤ +│ netdev_alloc_skb() │ 905 Mb/s │ 892 Mb/s │ +│ napi_alloc_frag() + build_skb() │ 918 Mb/s │ 917 Mb/s │ +└─────────────────────────────────┴─────────────────────┴────────────────────┘ + +Another ideas: +1. napi_build_skb() +2. skb_copy_from_linear_data() for small packets + +Those need proper testing first though. That can be done later. + +Signed-off-by: Rafał Miłecki <rafal@milecki.pl> +Link: https://lore.kernel.org/r/20221025132245.22871-1-zajec5@gmail.com +Signed-off-by: Paolo Abeni <pabeni@redhat.com> +--- + drivers/net/ethernet/broadcom/bcm4908_enet.c | 53 +++++++++++++------- + 1 file changed, 36 insertions(+), 17 deletions(-) + +--- a/drivers/net/ethernet/broadcom/bcm4908_enet.c ++++ b/drivers/net/ethernet/broadcom/bcm4908_enet.c +@@ -36,13 +36,24 @@ + #define ENET_MAX_ETH_OVERHEAD (ETH_HLEN + BRCM_MAX_TAG_LEN + VLAN_HLEN + \ + ETH_FCS_LEN + 4) /* 32 */ + ++#define ENET_RX_SKB_BUF_SIZE (NET_SKB_PAD + NET_IP_ALIGN + \ ++ ETH_HLEN + BRCM_MAX_TAG_LEN + VLAN_HLEN + \ ++ ENET_MTU_MAX + ETH_FCS_LEN + 4) ++#define ENET_RX_SKB_BUF_ALLOC_SIZE (SKB_DATA_ALIGN(ENET_RX_SKB_BUF_SIZE) + \ ++ SKB_DATA_ALIGN(sizeof(struct skb_shared_info))) ++#define ENET_RX_BUF_DMA_OFFSET (NET_SKB_PAD + NET_IP_ALIGN) ++#define ENET_RX_BUF_DMA_SIZE (ENET_RX_SKB_BUF_SIZE - ENET_RX_BUF_DMA_OFFSET) ++ + struct bcm4908_enet_dma_ring_bd { + __le32 ctl; + __le32 addr; + } __packed; + + struct bcm4908_enet_dma_ring_slot { +- struct sk_buff *skb; ++ union { ++ void *buf; /* RX */ ++ struct sk_buff *skb; /* TX */ ++ }; + unsigned int len; + dma_addr_t dma_addr; + }; +@@ -259,22 +270,21 @@ static int bcm4908_enet_dma_alloc_rx_buf + u32 tmp; + int err; + +- slot->len = ENET_MTU_MAX + ENET_MAX_ETH_OVERHEAD; +- +- slot->skb = netdev_alloc_skb(enet->netdev, slot->len); +- if (!slot->skb) ++ slot->buf = napi_alloc_frag(ENET_RX_SKB_BUF_ALLOC_SIZE); ++ if (!slot->buf) + return -ENOMEM; + +- slot->dma_addr = dma_map_single(dev, slot->skb->data, slot->len, DMA_FROM_DEVICE); ++ slot->dma_addr = dma_map_single(dev, slot->buf + ENET_RX_BUF_DMA_OFFSET, ++ ENET_RX_BUF_DMA_SIZE, DMA_FROM_DEVICE); + err = dma_mapping_error(dev, slot->dma_addr); + if (err) { + dev_err(dev, "Failed to map DMA buffer: %d\n", err); +- kfree_skb(slot->skb); +- slot->skb = NULL; ++ skb_free_frag(slot->buf); ++ slot->buf = NULL; + return err; + } + +- tmp = slot->len << DMA_CTL_LEN_DESC_BUFLENGTH_SHIFT; ++ tmp = ENET_RX_BUF_DMA_SIZE << DMA_CTL_LEN_DESC_BUFLENGTH_SHIFT; + tmp |= DMA_CTL_STATUS_OWN; + if (idx == enet->rx_ring.length - 1) + tmp |= DMA_CTL_STATUS_WRAP; +@@ -314,11 +324,11 @@ static void bcm4908_enet_dma_uninit(stru + + for (i = rx_ring->length - 1; i >= 0; i--) { + slot = &rx_ring->slots[i]; +- if (!slot->skb) ++ if (!slot->buf) + continue; + dma_unmap_single(dev, slot->dma_addr, slot->len, DMA_FROM_DEVICE); +- kfree_skb(slot->skb); +- slot->skb = NULL; ++ skb_free_frag(slot->buf); ++ slot->buf = NULL; + } + } + +@@ -576,6 +586,7 @@ static int bcm4908_enet_poll_rx(struct n + while (handled < weight) { + struct bcm4908_enet_dma_ring_bd *buf_desc; + struct bcm4908_enet_dma_ring_slot slot; ++ struct sk_buff *skb; + u32 ctl; + int len; + int err; +@@ -599,16 +610,24 @@ static int bcm4908_enet_poll_rx(struct n + + if (len < ETH_ZLEN || + (ctl & (DMA_CTL_STATUS_SOP | DMA_CTL_STATUS_EOP)) != (DMA_CTL_STATUS_SOP | DMA_CTL_STATUS_EOP)) { +- kfree_skb(slot.skb); ++ skb_free_frag(slot.buf); + enet->netdev->stats.rx_dropped++; + break; + } + +- dma_unmap_single(dev, slot.dma_addr, slot.len, DMA_FROM_DEVICE); ++ dma_unmap_single(dev, slot.dma_addr, ENET_RX_BUF_DMA_SIZE, DMA_FROM_DEVICE); ++ ++ skb = build_skb(slot.buf, ENET_RX_SKB_BUF_ALLOC_SIZE); ++ if (unlikely(!skb)) { ++ skb_free_frag(slot.buf); ++ enet->netdev->stats.rx_dropped++; ++ break; ++ } ++ skb_reserve(skb, ENET_RX_BUF_DMA_OFFSET); ++ skb_put(skb, len - ETH_FCS_LEN); ++ skb->protocol = eth_type_trans(skb, enet->netdev); + +- skb_put(slot.skb, len - ETH_FCS_LEN); +- slot.skb->protocol = eth_type_trans(slot.skb, enet->netdev); +- netif_receive_skb(slot.skb); ++ netif_receive_skb(skb); + + enet->netdev->stats.rx_packets++; + enet->netdev->stats.rx_bytes += len; |