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bgmac: pass received packet to the netif instead of copying it
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 <zajec5@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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3af390e2c5
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@ -315,7 +315,6 @@ static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring,
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struct device *dma_dev = bgmac->core->dma_dev;
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struct bgmac_slot_info *slot = &ring->slots[ring->start];
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struct sk_buff *skb = slot->skb;
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struct sk_buff *new_skb;
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struct bgmac_rx_header *rx;
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u16 len, flags;
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@ -328,38 +327,51 @@ static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring,
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len = le16_to_cpu(rx->len);
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flags = le16_to_cpu(rx->flags);
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/* Check for poison and drop or pass the packet */
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if (len == 0xdead && flags == 0xbeef) {
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bgmac_err(bgmac, "Found poisoned packet at slot %d, DMA issue!\n",
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ring->start);
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} else {
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do {
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dma_addr_t old_dma_addr = slot->dma_addr;
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int err;
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/* Check for poison and drop or pass the packet */
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if (len == 0xdead && flags == 0xbeef) {
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bgmac_err(bgmac, "Found poisoned packet at slot %d, DMA issue!\n",
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ring->start);
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dma_sync_single_for_device(dma_dev,
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slot->dma_addr,
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BGMAC_RX_BUF_SIZE,
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DMA_FROM_DEVICE);
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break;
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}
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/* Omit CRC. */
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len -= ETH_FCS_LEN;
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new_skb = netdev_alloc_skb_ip_align(bgmac->net_dev, len);
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if (new_skb) {
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skb_put(new_skb, len);
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skb_copy_from_linear_data_offset(skb, BGMAC_RX_FRAME_OFFSET,
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new_skb->data,
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len);
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skb_checksum_none_assert(skb);
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new_skb->protocol =
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eth_type_trans(new_skb, bgmac->net_dev);
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netif_receive_skb(new_skb);
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handled++;
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} else {
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bgmac->net_dev->stats.rx_dropped++;
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bgmac_err(bgmac, "Allocation of skb for copying packet failed!\n");
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/* Prepare new skb as replacement */
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err = bgmac_dma_rx_skb_for_slot(bgmac, slot);
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if (err) {
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/* Poison the old skb */
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rx->len = cpu_to_le16(0xdead);
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rx->flags = cpu_to_le16(0xbeef);
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dma_sync_single_for_device(dma_dev,
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slot->dma_addr,
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BGMAC_RX_BUF_SIZE,
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DMA_FROM_DEVICE);
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break;
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}
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bgmac_dma_rx_setup_desc(bgmac, ring, ring->start);
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/* Poison the old skb */
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rx->len = cpu_to_le16(0xdead);
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rx->flags = cpu_to_le16(0xbeef);
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}
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/* Unmap old skb, we'll pass it to the netfif */
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dma_unmap_single(dma_dev, old_dma_addr,
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BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
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/* Make it back accessible to the hardware */
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dma_sync_single_for_device(dma_dev, slot->dma_addr,
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BGMAC_RX_BUF_SIZE, DMA_FROM_DEVICE);
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skb_put(skb, BGMAC_RX_FRAME_OFFSET + len);
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skb_pull(skb, BGMAC_RX_FRAME_OFFSET);
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skb_checksum_none_assert(skb);
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skb->protocol = eth_type_trans(skb, bgmac->net_dev);
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netif_receive_skb(skb);
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handled++;
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} while (0);
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if (++ring->start >= BGMAC_RX_RING_SLOTS)
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ring->start = 0;
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