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Commit a03bb56e authored by Govindarajulu Varadarajan's avatar Govindarajulu Varadarajan Committed by David S. Miller
Browse files

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: default avatarGovindarajulu Varadarajan <_govind@gmx.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e020836d

drivers/net/ethernet/cisco/enic/enic.h

+1 −0
Original line number Diff line number Diff line
@@ -186,6 +186,7 @@ struct enic { 
	____cacheline_aligned struct vnic_cq cq[ENIC_CQ_MAX];

	unsigned int cq_count;

	struct enic_rfs_flw_tbl rfs_h;

	u32 rx_copybreak;

};



static inline struct device *enic_get_dev(struct enic *enic)

drivers/net/ethernet/cisco/enic/enic_main.c

+47 −3
Original line number Diff line number Diff line
@@ -66,6 +66,8 @@ 
#define PCI_DEVICE_ID_CISCO_VIC_ENET_DYN     0x0044  /* enet dynamic vnic */

#define PCI_DEVICE_ID_CISCO_VIC_ENET_VF      0x0071  /* enet SRIOV VF */



#define RX_COPYBREAK_DEFAULT		256



/* Supported devices */

static const struct pci_device_id enic_id_table[] = {

	{ PCI_VDEVICE(CISCO, PCI_DEVICE_ID_CISCO_VIC_ENET) },
@@ -924,6 +926,7 @@ static void enic_free_rq_buf(struct vnic_rq *rq, struct vnic_rq_buf *buf) 
	pci_unmap_single(enic->pdev, buf->dma_addr,

		buf->len, PCI_DMA_FROMDEVICE);

	dev_kfree_skb_any(buf->os_buf);

	buf->os_buf = NULL;

}



static int enic_rq_alloc_buf(struct vnic_rq *rq)
@@ -934,7 +937,24 @@ static int enic_rq_alloc_buf(struct vnic_rq *rq) 
	unsigned int len = netdev->mtu + VLAN_ETH_HLEN;

	unsigned int os_buf_index = 0;

	dma_addr_t dma_addr;

	struct vnic_rq_buf *buf = rq->to_use;



	if (buf->os_buf) {

		buf = buf->next;

		rq->to_use = buf;

		rq->ring.desc_avail--;

		if ((buf->index & VNIC_RQ_RETURN_RATE) == 0) {

			/* Adding write memory barrier prevents compiler and/or

			 * CPU reordering, thus avoiding descriptor posting

			 * before descriptor is initialized. Otherwise, hardware

			 * can read stale descriptor fields.

			 */

			wmb();

			iowrite32(buf->index, &rq->ctrl->posted_index);

		}



		return 0;

	}

	skb = netdev_alloc_skb_ip_align(netdev, len);

	if (!skb)

		return -ENOMEM;
@@ -957,6 +977,25 @@ static void enic_intr_update_pkt_size(struct vnic_rx_bytes_counter *pkt_size, 
		pkt_size->small_pkt_bytes_cnt += pkt_len;

}



static bool enic_rxcopybreak(struct net_device *netdev, struct sk_buff **skb,

			     struct vnic_rq_buf *buf, u16 len)

{

	struct enic *enic = netdev_priv(netdev);

	struct sk_buff *new_skb;



	if (len > enic->rx_copybreak)

		return false;

	new_skb = netdev_alloc_skb_ip_align(netdev, len);

	if (!new_skb)

		return false;

	pci_dma_sync_single_for_cpu(enic->pdev, buf->dma_addr, len,

				    DMA_FROM_DEVICE);

	memcpy(new_skb->data, (*skb)->data, len);

	*skb = new_skb;



	return true;

}



static void enic_rq_indicate_buf(struct vnic_rq *rq,

	struct cq_desc *cq_desc, struct vnic_rq_buf *buf,

	int skipped, void *opaque)
@@ -978,9 +1017,6 @@ static void enic_rq_indicate_buf(struct vnic_rq *rq, 
		return;



	skb = buf->os_buf;

	prefetch(skb->data - NET_IP_ALIGN);

	pci_unmap_single(enic->pdev, buf->dma_addr,

		buf->len, PCI_DMA_FROMDEVICE);



	cq_enet_rq_desc_dec((struct cq_enet_rq_desc *)cq_desc,

		&type, &color, &q_number, &completed_index,
@@ -1011,6 +1047,13 @@ static void enic_rq_indicate_buf(struct vnic_rq *rq, 
		/* Good receive

		 */



		if (!enic_rxcopybreak(netdev, &skb, buf, bytes_written)) {

			buf->os_buf = NULL;

			pci_unmap_single(enic->pdev, buf->dma_addr, buf->len,

					 PCI_DMA_FROMDEVICE);

		}

		prefetch(skb->data - NET_IP_ALIGN);



		skb_put(skb, bytes_written);

		skb->protocol = eth_type_trans(skb, netdev);

		skb_record_rx_queue(skb, q_number);
@@ -2531,6 +2574,7 @@ static int enic_probe(struct pci_dev *pdev, const struct pci_device_id *ent) 
		dev_err(dev, "Cannot register net device, aborting\n");

		goto err_out_dev_deinit;

	}

	enic->rx_copybreak = RX_COPYBREAK_DEFAULT;



	return 0;