From 92b9ccd34a9053c628d230fe27a7e0c10179910f Mon Sep 17 00:00:00 2001 From: =?utf8?q?Rafa=C5=82=20Mi=C5=82ecki?= Date: Wed, 30 Oct 2013 08:00:00 +0100 Subject: [PATCH] bgmac: pass received packet to the netif instead of copying it MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Copying whole packets with skb_copy_from_linear_data_offset is a pretty bad idea. CPU was spending time in __copy_user_common and network performance was lower. With the new solution iperf-measured speed increased from 116Mb/s to 134Mb/s. Signed-off-by: Rafał Miłecki Signed-off-by: David S. Miller --- drivers/net/ethernet/broadcom/bgmac.c | 66 ++++++++++++++++----------- 1 file changed, 39 insertions(+), 27 deletions(-) diff --git a/drivers/net/ethernet/broadcom/bgmac.c b/drivers/net/ethernet/broadcom/bgmac.c index 4f9beed54506..a98778e3af84 100644 --- a/drivers/net/ethernet/broadcom/bgmac.c +++ b/drivers/net/ethernet/broadcom/bgmac.c @@ -315,7 +315,6 @@ static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring, struct device *dma_dev = bgmac->core->dma_dev; struct bgmac_slot_info *slot = &ring->slots[ring->start]; struct sk_buff *skb = slot->skb; - struct sk_buff *new_skb; struct bgmac_rx_header *rx; u16 len, flags; @@ -328,38 +327,51 @@ static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring, len = le16_to_cpu(rx->len); flags = le16_to_cpu(rx->flags); - /* Check for poison and drop or pass the packet */ - if (len == 0xdead && flags == 0xbeef) { - bgmac_err(bgmac, "Found poisoned packet at slot %d, DMA issue!\n", - ring->start); - } else { + do { + dma_addr_t old_dma_addr = slot->dma_addr; + int err; + + /* Check for poison and drop or pass the packet */ + if (len == 0xdead && flags == 0xbeef) { + bgmac_err(bgmac, "Found poisoned packet at slot %d, DMA issue!\n", + ring->start); + dma_sync_single_for_device(dma_dev, + slot->dma_addr, + BGMAC_RX_BUF_SIZE, + DMA_FROM_DEVICE); + break; + } + /* Omit CRC. */ len -= ETH_FCS_LEN; - new_skb = netdev_alloc_skb_ip_align(bgmac->net_dev, len); - if (new_skb) { - skb_put(new_skb, len); - skb_copy_from_linear_data_offset(skb, BGMAC_RX_FRAME_OFFSET, - new_skb->data, - len); - skb_checksum_none_assert(skb); - new_skb->protocol = - eth_type_trans(new_skb, bgmac->net_dev); - netif_receive_skb(new_skb); - handled++; - } else { - bgmac->net_dev->stats.rx_dropped++; - bgmac_err(bgmac, "Allocation of skb for copying packet failed!\n"); + /* Prepare new skb as replacement */ + err = bgmac_dma_rx_skb_for_slot(bgmac, slot); + if (err) { + /* Poison the old skb */ + rx->len = cpu_to_le16(0xdead); + rx->flags = cpu_to_le16(0xbeef); + + dma_sync_single_for_device(dma_dev, + slot->dma_addr, + BGMAC_RX_BUF_SIZE, + DMA_FROM_DEVICE); + break; } + bgmac_dma_rx_setup_desc(bgmac, ring, ring->start); - /* Poison the old skb */ - rx->len = cpu_to_le16(0xdead); - rx->flags = cpu_to_le16(0xbeef); - } + /* Unmap old skb, we'll pass it to the netfif */ + dma_unmap_single(dma_dev, old_dma_addr, + BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE); + + skb_put(skb, BGMAC_RX_FRAME_OFFSET + len); + skb_pull(skb, BGMAC_RX_FRAME_OFFSET); - /* Make it back accessible to the hardware */ - dma_sync_single_for_device(dma_dev, slot->dma_addr, - BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE); + skb_checksum_none_assert(skb); + skb->protocol = eth_type_trans(skb, bgmac->net_dev); + netif_receive_skb(skb); + handled++; + } while (0); if (++ring->start >= BGMAC_RX_RING_SLOTS) ring->start = 0; -- 2.20.1