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authorLennert Buytenhek <buytenh@wantstofly.org>2008-09-12 22:16:15 -0400
committerLennert Buytenhek <buytenh@marvell.com>2008-09-14 08:09:06 -0400
commita418950c1378c4a3722baecdbe98df78ea23f231 (patch)
tree6c92a9e59c85c82b306c55bdd0a5b7fc3ce89516
parent8fd89211bf8e8e60415c66e5546c1478f5e8bc2b (diff)
mv643xx_eth: avoid dropping tx lock during transmit reclaim
By moving DMA unmapping during transmit reclaim back under the netif tx lock, we avoid the situation where we read the DMA address and buffer length from the descriptor under the lock and then not do anything with that data after dropping the lock on platforms where the DMA unmapping routines are all NOPs (which is the case on all ARM platforms that mv643xx_eth is used on at least). This saves two uncached reads, which makes a small but measurable performance difference in routing benchmarks. Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
-rw-r--r--drivers/net/mv643xx_eth.c22
1 files changed, 7 insertions, 15 deletions
diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index d653b5a19e77..7410eca87823 100644
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -866,8 +866,6 @@ static int txq_reclaim(struct tx_queue *txq, int budget, int force)
866 struct tx_desc *desc; 866 struct tx_desc *desc;
867 u32 cmd_sts; 867 u32 cmd_sts;
868 struct sk_buff *skb; 868 struct sk_buff *skb;
869 dma_addr_t addr;
870 int count;
871 869
872 tx_index = txq->tx_used_desc; 870 tx_index = txq->tx_used_desc;
873 desc = &txq->tx_desc_area[tx_index]; 871 desc = &txq->tx_desc_area[tx_index];
@@ -886,8 +884,6 @@ static int txq_reclaim(struct tx_queue *txq, int budget, int force)
886 reclaimed++; 884 reclaimed++;
887 txq->tx_desc_count--; 885 txq->tx_desc_count--;
888 886
889 addr = desc->buf_ptr;
890 count = desc->byte_cnt;
891 skb = txq->tx_skb[tx_index]; 887 skb = txq->tx_skb[tx_index];
892 txq->tx_skb[tx_index] = NULL; 888 txq->tx_skb[tx_index] = NULL;
893 889
@@ -896,20 +892,16 @@ static int txq_reclaim(struct tx_queue *txq, int budget, int force)
896 mp->dev->stats.tx_errors++; 892 mp->dev->stats.tx_errors++;
897 } 893 }
898 894
899 /* 895 if (cmd_sts & TX_FIRST_DESC) {
900 * Drop tx queue lock while we free the skb. 896 dma_unmap_single(NULL, desc->buf_ptr,
901 */ 897 desc->byte_cnt, DMA_TO_DEVICE);
902 __netif_tx_unlock(nq); 898 } else {
903 899 dma_unmap_page(NULL, desc->buf_ptr,
904 if (cmd_sts & TX_FIRST_DESC) 900 desc->byte_cnt, DMA_TO_DEVICE);
905 dma_unmap_single(NULL, addr, count, DMA_TO_DEVICE); 901 }
906 else
907 dma_unmap_page(NULL, addr, count, DMA_TO_DEVICE);
908 902
909 if (skb) 903 if (skb)
910 dev_kfree_skb(skb); 904 dev_kfree_skb(skb);
911
912 __netif_tx_lock(nq, smp_processor_id());
913 } 905 }
914 906
915 __netif_tx_unlock(nq); 907 __netif_tx_unlock(nq);