enic: implement rx_copybreak
Calling dma_map_single()/dma_unmap_single() is quite expensive compared to copying a small packet. So let's copy short frames and keep the buffers mapped. Signed-off-by: Govindarajulu Varadarajan <_govind@gmx.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -186,6 +186,7 @@ struct enic {
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____cacheline_aligned struct vnic_cq cq[ENIC_CQ_MAX];
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unsigned int cq_count;
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struct enic_rfs_flw_tbl rfs_h;
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u32 rx_copybreak;
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};
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static inline struct device *enic_get_dev(struct enic *enic)
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@ -66,6 +66,8 @@
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#define PCI_DEVICE_ID_CISCO_VIC_ENET_DYN 0x0044 /* enet dynamic vnic */
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#define PCI_DEVICE_ID_CISCO_VIC_ENET_VF 0x0071 /* enet SRIOV VF */
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#define RX_COPYBREAK_DEFAULT 256
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/* Supported devices */
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static const struct pci_device_id enic_id_table[] = {
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{ PCI_VDEVICE(CISCO, PCI_DEVICE_ID_CISCO_VIC_ENET) },
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@ -924,6 +926,7 @@ static void enic_free_rq_buf(struct vnic_rq *rq, struct vnic_rq_buf *buf)
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pci_unmap_single(enic->pdev, buf->dma_addr,
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buf->len, PCI_DMA_FROMDEVICE);
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dev_kfree_skb_any(buf->os_buf);
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buf->os_buf = NULL;
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}
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static int enic_rq_alloc_buf(struct vnic_rq *rq)
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@ -934,7 +937,24 @@ static int enic_rq_alloc_buf(struct vnic_rq *rq)
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unsigned int len = netdev->mtu + VLAN_ETH_HLEN;
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unsigned int os_buf_index = 0;
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dma_addr_t dma_addr;
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struct vnic_rq_buf *buf = rq->to_use;
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if (buf->os_buf) {
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buf = buf->next;
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rq->to_use = buf;
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rq->ring.desc_avail--;
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if ((buf->index & VNIC_RQ_RETURN_RATE) == 0) {
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/* Adding write memory barrier prevents compiler and/or
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* CPU reordering, thus avoiding descriptor posting
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* before descriptor is initialized. Otherwise, hardware
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* can read stale descriptor fields.
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*/
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wmb();
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iowrite32(buf->index, &rq->ctrl->posted_index);
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}
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return 0;
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}
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skb = netdev_alloc_skb_ip_align(netdev, len);
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if (!skb)
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return -ENOMEM;
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@ -957,6 +977,25 @@ static void enic_intr_update_pkt_size(struct vnic_rx_bytes_counter *pkt_size,
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pkt_size->small_pkt_bytes_cnt += pkt_len;
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}
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static bool enic_rxcopybreak(struct net_device *netdev, struct sk_buff **skb,
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struct vnic_rq_buf *buf, u16 len)
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{
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struct enic *enic = netdev_priv(netdev);
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struct sk_buff *new_skb;
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if (len > enic->rx_copybreak)
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return false;
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new_skb = netdev_alloc_skb_ip_align(netdev, len);
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if (!new_skb)
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return false;
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pci_dma_sync_single_for_cpu(enic->pdev, buf->dma_addr, len,
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DMA_FROM_DEVICE);
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memcpy(new_skb->data, (*skb)->data, len);
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*skb = new_skb;
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return true;
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}
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static void enic_rq_indicate_buf(struct vnic_rq *rq,
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struct cq_desc *cq_desc, struct vnic_rq_buf *buf,
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int skipped, void *opaque)
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@ -978,9 +1017,6 @@ static void enic_rq_indicate_buf(struct vnic_rq *rq,
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return;
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skb = buf->os_buf;
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prefetch(skb->data - NET_IP_ALIGN);
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pci_unmap_single(enic->pdev, buf->dma_addr,
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buf->len, PCI_DMA_FROMDEVICE);
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cq_enet_rq_desc_dec((struct cq_enet_rq_desc *)cq_desc,
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&type, &color, &q_number, &completed_index,
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@ -1011,6 +1047,13 @@ static void enic_rq_indicate_buf(struct vnic_rq *rq,
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/* Good receive
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*/
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if (!enic_rxcopybreak(netdev, &skb, buf, bytes_written)) {
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buf->os_buf = NULL;
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pci_unmap_single(enic->pdev, buf->dma_addr, buf->len,
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PCI_DMA_FROMDEVICE);
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}
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prefetch(skb->data - NET_IP_ALIGN);
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skb_put(skb, bytes_written);
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skb->protocol = eth_type_trans(skb, netdev);
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skb_record_rx_queue(skb, q_number);
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@ -2531,6 +2574,7 @@ static int enic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
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dev_err(dev, "Cannot register net device, aborting\n");
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goto err_out_dev_deinit;
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}
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enic->rx_copybreak = RX_COPYBREAK_DEFAULT;
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return 0;
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