From a03bb56e67c357980dae886683733dab5583dc14 Mon Sep 17 00:00:00 2001 From: Govindarajulu Varadarajan <_govind@gmx.com> Date: Wed, 3 Sep 2014 03:17:19 +0530 Subject: [PATCH] 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 --- drivers/net/ethernet/cisco/enic/enic.h | 1 + drivers/net/ethernet/cisco/enic/enic_main.c | 50 +++++++++++++++++++-- 2 files changed, 48 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/cisco/enic/enic.h b/drivers/net/ethernet/cisco/enic/enic.h index 962510f391df..5ba5ad071bb6 100644 --- a/drivers/net/ethernet/cisco/enic/enic.h +++ b/drivers/net/ethernet/cisco/enic/enic.h @@ -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) diff --git a/drivers/net/ethernet/cisco/enic/enic_main.c b/drivers/net/ethernet/cisco/enic/enic_main.c index c8832bc1c5f7..929bfe70080a 100644 --- a/drivers/net/ethernet/cisco/enic/enic_main.c +++ b/drivers/net/ethernet/cisco/enic/enic_main.c @@ -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; -- 2.20.1