From 4acb20b46214bc866945340b4d9e1de77700d6a3 Mon Sep 17 00:00:00 2001 From: Ilias Apalodimas Date: Thu, 8 Nov 2018 17:19:54 +0200 Subject: [PATCH] net: socionext: different approach on DMA Current driver dynamically allocates an skb and maps it as DMA Rx buffer. In order to prepare for upcoming XDP changes, let's introduce a different allocation scheme. Buffers are allocated dynamically and mapped into hardware. During the Rx operation the driver uses build_skb() to produce the necessary buffers for the network stack. This change increases performance ~15% on 64b packets with smmu disabled and ~5% with smmu enabled Signed-off-by: Ilias Apalodimas Signed-off-by: David S. Miller --- drivers/net/ethernet/socionext/netsec.c | 227 +++++++++++++----------- 1 file changed, 128 insertions(+), 99 deletions(-) diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c index d9d0d03e4ce7..9d24f299798a 100644 --- a/drivers/net/ethernet/socionext/netsec.c +++ b/drivers/net/ethernet/socionext/netsec.c @@ -234,6 +234,9 @@ #define DESC_NUM 256 +#define NETSEC_SKB_PAD (NET_SKB_PAD + NET_IP_ALIGN) +#define NETSEC_RX_BUF_SZ 1536 + #define DESC_SZ sizeof(struct netsec_de) #define NETSEC_F_NETSEC_VER_MAJOR_NUM(x) ((x) & 0xffff0000) @@ -571,34 +574,10 @@ static const struct ethtool_ops netsec_ethtool_ops = { /************* NETDEV_OPS FOLLOW *************/ -static struct sk_buff *netsec_alloc_skb(struct netsec_priv *priv, - struct netsec_desc *desc) -{ - struct sk_buff *skb; - - if (device_get_dma_attr(priv->dev) == DEV_DMA_COHERENT) { - skb = netdev_alloc_skb_ip_align(priv->ndev, desc->len); - } else { - desc->len = L1_CACHE_ALIGN(desc->len); - skb = netdev_alloc_skb(priv->ndev, desc->len); - } - if (!skb) - return NULL; - - desc->addr = skb->data; - desc->dma_addr = dma_map_single(priv->dev, desc->addr, desc->len, - DMA_FROM_DEVICE); - if (dma_mapping_error(priv->dev, desc->dma_addr)) { - dev_kfree_skb_any(skb); - return NULL; - } - return skb; -} static void netsec_set_rx_de(struct netsec_priv *priv, struct netsec_desc_ring *dring, u16 idx, - const struct netsec_desc *desc, - struct sk_buff *skb) + const struct netsec_desc *desc) { struct netsec_de *de = dring->vaddr + DESC_SZ * idx; u32 attr = (1 << NETSEC_RX_PKT_OWN_FIELD) | @@ -617,59 +596,6 @@ static void netsec_set_rx_de(struct netsec_priv *priv, dring->desc[idx].dma_addr = desc->dma_addr; dring->desc[idx].addr = desc->addr; dring->desc[idx].len = desc->len; - dring->desc[idx].skb = skb; -} - -static struct sk_buff *netsec_get_rx_de(struct netsec_priv *priv, - struct netsec_desc_ring *dring, - u16 idx, - struct netsec_rx_pkt_info *rxpi, - struct netsec_desc *desc, u16 *len) -{ - struct netsec_de de = {}; - - memcpy(&de, dring->vaddr + DESC_SZ * idx, DESC_SZ); - - *len = de.buf_len_info >> 16; - - rxpi->err_flag = (de.attr >> NETSEC_RX_PKT_ER_FIELD) & 1; - rxpi->rx_cksum_result = (de.attr >> NETSEC_RX_PKT_CO_FIELD) & 3; - rxpi->err_code = (de.attr >> NETSEC_RX_PKT_ERR_FIELD) & - NETSEC_RX_PKT_ERR_MASK; - *desc = dring->desc[idx]; - return desc->skb; -} - -static struct sk_buff *netsec_get_rx_pkt_data(struct netsec_priv *priv, - struct netsec_rx_pkt_info *rxpi, - struct netsec_desc *desc, - u16 *len) -{ - struct netsec_desc_ring *dring = &priv->desc_ring[NETSEC_RING_RX]; - struct sk_buff *tmp_skb, *skb = NULL; - struct netsec_desc td; - int tail; - - *rxpi = (struct netsec_rx_pkt_info){}; - - td.len = priv->ndev->mtu + 22; - - tmp_skb = netsec_alloc_skb(priv, &td); - - tail = dring->tail; - - if (!tmp_skb) { - netsec_set_rx_de(priv, dring, tail, &dring->desc[tail], - dring->desc[tail].skb); - } else { - skb = netsec_get_rx_de(priv, dring, tail, rxpi, desc, len); - netsec_set_rx_de(priv, dring, tail, &td, tmp_skb); - } - - /* move tail ahead */ - dring->tail = (dring->tail + 1) % DESC_NUM; - - return skb; } static int netsec_clean_tx_dring(struct netsec_priv *priv, int budget) @@ -736,19 +662,65 @@ static int netsec_process_tx(struct netsec_priv *priv, int budget) return done; } +static void *netsec_alloc_rx_data(struct netsec_priv *priv, + dma_addr_t *dma_handle, u16 *desc_len) +{ + size_t total_len = SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); + size_t payload_len = NETSEC_RX_BUF_SZ; + dma_addr_t mapping; + void *buf; + + total_len += SKB_DATA_ALIGN(payload_len + NETSEC_SKB_PAD); + + buf = napi_alloc_frag(total_len); + if (!buf) + return NULL; + + mapping = dma_map_single(priv->dev, buf + NETSEC_SKB_PAD, payload_len, + DMA_FROM_DEVICE); + if (unlikely(dma_mapping_error(priv->dev, mapping))) + goto err_out; + + *dma_handle = mapping; + *desc_len = payload_len; + + return buf; + +err_out: + skb_free_frag(buf); + return NULL; +} + +static void netsec_rx_fill(struct netsec_priv *priv, u16 from, u16 num) +{ + struct netsec_desc_ring *dring = &priv->desc_ring[NETSEC_RING_RX]; + u16 idx = from; + + while (num) { + netsec_set_rx_de(priv, dring, idx, &dring->desc[idx]); + idx++; + if (idx >= DESC_NUM) + idx = 0; + num--; + } +} + static int netsec_process_rx(struct netsec_priv *priv, int budget) { struct netsec_desc_ring *dring = &priv->desc_ring[NETSEC_RING_RX]; struct net_device *ndev = priv->ndev; struct netsec_rx_pkt_info rx_info; - int done = 0; - struct netsec_desc desc; struct sk_buff *skb; - u16 len; + int done = 0; while (done < budget) { u16 idx = dring->tail; struct netsec_de *de = dring->vaddr + (DESC_SZ * idx); + struct netsec_desc *desc = &dring->desc[idx]; + u16 pkt_len, desc_len; + dma_addr_t dma_handle; + void *buf_addr; + u32 truesize; if (de->attr & (1U << NETSEC_RX_PKT_OWN_FIELD)) { /* reading the register clears the irq */ @@ -762,18 +734,59 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget) */ dma_rmb(); done++; - skb = netsec_get_rx_pkt_data(priv, &rx_info, &desc, &len); - if (unlikely(!skb) || rx_info.err_flag) { + + pkt_len = de->buf_len_info >> 16; + rx_info.err_code = (de->attr >> NETSEC_RX_PKT_ERR_FIELD) & + NETSEC_RX_PKT_ERR_MASK; + rx_info.err_flag = (de->attr >> NETSEC_RX_PKT_ER_FIELD) & 1; + if (rx_info.err_flag) { netif_err(priv, drv, priv->ndev, - "%s: rx fail err(%d)\n", - __func__, rx_info.err_code); + "%s: rx fail err(%d)\n", __func__, + rx_info.err_code); ndev->stats.rx_dropped++; + dring->tail = (dring->tail + 1) % DESC_NUM; + /* reuse buffer page frag */ + netsec_rx_fill(priv, idx, 1); continue; } + rx_info.rx_cksum_result = + (de->attr >> NETSEC_RX_PKT_CO_FIELD) & 3; - dma_unmap_single(priv->dev, desc.dma_addr, desc.len, - DMA_FROM_DEVICE); - skb_put(skb, len); + /* allocate a fresh buffer and map it to the hardware. + * This will eventually replace the old buffer in the hardware + */ + buf_addr = netsec_alloc_rx_data(priv, &dma_handle, &desc_len); + if (unlikely(!buf_addr)) + break; + + dma_sync_single_for_cpu(priv->dev, desc->dma_addr, pkt_len, + DMA_FROM_DEVICE); + prefetch(desc->addr); + + truesize = SKB_DATA_ALIGN(desc->len + NETSEC_SKB_PAD) + + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); + skb = build_skb(desc->addr, truesize); + if (unlikely(!skb)) { + /* free the newly allocated buffer, we are not going to + * use it + */ + dma_unmap_single(priv->dev, dma_handle, desc_len, + DMA_FROM_DEVICE); + skb_free_frag(buf_addr); + netif_err(priv, drv, priv->ndev, + "rx failed to build skb\n"); + break; + } + dma_unmap_single_attrs(priv->dev, desc->dma_addr, desc->len, + DMA_FROM_DEVICE, DMA_ATTR_SKIP_CPU_SYNC); + + /* Update the descriptor with the new buffer we allocated */ + desc->len = desc_len; + desc->dma_addr = dma_handle; + desc->addr = buf_addr; + + skb_reserve(skb, NETSEC_SKB_PAD); + skb_put(skb, pkt_len); skb->protocol = eth_type_trans(skb, priv->ndev); if (priv->rx_cksum_offload_flag && @@ -782,8 +795,11 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget) if (napi_gro_receive(&priv->napi, skb) != GRO_DROP) { ndev->stats.rx_packets++; - ndev->stats.rx_bytes += len; + ndev->stats.rx_bytes += pkt_len; } + + netsec_rx_fill(priv, idx, 1); + dring->tail = (dring->tail + 1) % DESC_NUM; } return done; @@ -946,7 +962,10 @@ static void netsec_uninit_pkt_dring(struct netsec_priv *priv, int id) dma_unmap_single(priv->dev, desc->dma_addr, desc->len, id == NETSEC_RING_RX ? DMA_FROM_DEVICE : DMA_TO_DEVICE); - dev_kfree_skb(desc->skb); + if (id == NETSEC_RING_RX) + skb_free_frag(desc->addr); + else if (id == NETSEC_RING_TX) + dev_kfree_skb(desc->skb); } memset(dring->desc, 0, sizeof(struct netsec_desc) * DESC_NUM); @@ -1002,22 +1021,30 @@ err: static int netsec_setup_rx_dring(struct netsec_priv *priv) { struct netsec_desc_ring *dring = &priv->desc_ring[NETSEC_RING_RX]; - struct netsec_desc desc; - struct sk_buff *skb; - int n; + int i; - desc.len = priv->ndev->mtu + 22; + for (i = 0; i < DESC_NUM; i++) { + struct netsec_desc *desc = &dring->desc[i]; + dma_addr_t dma_handle; + void *buf; + u16 len; - for (n = 0; n < DESC_NUM; n++) { - skb = netsec_alloc_skb(priv, &desc); - if (!skb) { + buf = netsec_alloc_rx_data(priv, &dma_handle, &len); + if (!buf) { netsec_uninit_pkt_dring(priv, NETSEC_RING_RX); - return -ENOMEM; + goto err_out; } - netsec_set_rx_de(priv, dring, n, &desc, skb); + desc->dma_addr = dma_handle; + desc->addr = buf; + desc->len = len; } + netsec_rx_fill(priv, 0, DESC_NUM); + return 0; + +err_out: + return -ENOMEM; } static int netsec_netdev_load_ucode_region(struct netsec_priv *priv, u32 reg, @@ -1377,6 +1404,8 @@ static int netsec_netdev_init(struct net_device *ndev) int ret; u16 data; + BUILD_BUG_ON_NOT_POWER_OF_2(DESC_NUM); + ret = netsec_alloc_dring(priv, NETSEC_RING_TX); if (ret) return ret; -- 2.39.5