[PATCH 1/1] forcedeth: optimize the xmit/rx with unlikely
From: Zhu Yanjun <hidden>
Date: 2017-09-22 14:18:21
In the xmit/rx fastpath, the function dma_map_single rarely fails. Therefore, add an unlikely() optimization to this error check conditional. Signed-off-by: Zhu Yanjun <redacted> --- drivers/net/ethernet/nvidia/forcedeth.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/drivers/net/ethernet/nvidia/forcedeth.c b/drivers/net/ethernet/nvidia/forcedeth.c
index 0a7ba3a..63a9e1e 100644
--- a/drivers/net/ethernet/nvidia/forcedeth.c
+++ b/drivers/net/ethernet/nvidia/forcedeth.c@@ -1816,8 +1816,8 @@ static int nv_alloc_rx(struct net_device *dev) skb->data, skb_tailroom(skb), DMA_FROM_DEVICE); - if (dma_mapping_error(&np->pci_dev->dev, - np->put_rx_ctx->dma)) { + if (unlikely(dma_mapping_error(&np->pci_dev->dev, + np->put_rx_ctx->dma))) { kfree_skb(skb); goto packet_dropped; }
@@ -1857,8 +1857,8 @@ static int nv_alloc_rx_optimized(struct net_device *dev) skb->data, skb_tailroom(skb), DMA_FROM_DEVICE); - if (dma_mapping_error(&np->pci_dev->dev, - np->put_rx_ctx->dma)) { + if (unlikely(dma_mapping_error(&np->pci_dev->dev, + np->put_rx_ctx->dma))) { kfree_skb(skb); goto packet_dropped; }
@@ -2224,8 +2224,8 @@ static netdev_tx_t nv_start_xmit(struct sk_buff *skb, struct net_device *dev) np->put_tx_ctx->dma = dma_map_single(&np->pci_dev->dev, skb->data + offset, bcnt, DMA_TO_DEVICE); - if (dma_mapping_error(&np->pci_dev->dev, - np->put_tx_ctx->dma)) { + if (unlikely(dma_mapping_error(&np->pci_dev->dev, + np->put_tx_ctx->dma))) { /* on DMA mapping error - drop the packet */ dev_kfree_skb_any(skb); u64_stats_update_begin(&np->swstats_tx_syncp);
@@ -2265,7 +2265,8 @@ static netdev_tx_t nv_start_xmit(struct sk_buff *skb, struct net_device *dev) frag, offset, bcnt, DMA_TO_DEVICE); - if (dma_mapping_error(&np->pci_dev->dev, np->put_tx_ctx->dma)) { + if (unlikely(dma_mapping_error(&np->pci_dev->dev, + np->put_tx_ctx->dma))) { /* Unwind the mapped fragments */ do {
@@ -2373,8 +2374,8 @@ static netdev_tx_t nv_start_xmit_optimized(struct sk_buff *skb, np->put_tx_ctx->dma = dma_map_single(&np->pci_dev->dev, skb->data + offset, bcnt, DMA_TO_DEVICE); - if (dma_mapping_error(&np->pci_dev->dev, - np->put_tx_ctx->dma)) { + if (unlikely(dma_mapping_error(&np->pci_dev->dev, + np->put_tx_ctx->dma))) { /* on DMA mapping error - drop the packet */ dev_kfree_skb_any(skb); u64_stats_update_begin(&np->swstats_tx_syncp);
@@ -2415,7 +2416,8 @@ static netdev_tx_t nv_start_xmit_optimized(struct sk_buff *skb, bcnt, DMA_TO_DEVICE); - if (dma_mapping_error(&np->pci_dev->dev, np->put_tx_ctx->dma)) { + if (unlikely(dma_mapping_error(&np->pci_dev->dev, + np->put_tx_ctx->dma))) { /* Unwind the mapped fragments */ do {
@@ -5070,8 +5072,8 @@ static int nv_loopback_test(struct net_device *dev) test_dma_addr = dma_map_single(&np->pci_dev->dev, tx_skb->data, skb_tailroom(tx_skb), DMA_FROM_DEVICE); - if (dma_mapping_error(&np->pci_dev->dev, - test_dma_addr)) { + if (unlikely(dma_mapping_error(&np->pci_dev->dev, + test_dma_addr))) { dev_kfree_skb_any(tx_skb); goto out; }
--
2.7.4