Changeset 31934

Timestamp:

2012-05-28T04:55:59+02:00 (6 years ago)

Author:

nbd

Message:

ar71xx: improve rx performance of the ethernet driver by using build_skb to deliver a cache-hot skb to the network stack

Location:

trunk/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx

Files:

• ag71xx.h (modified) (2 diffs)
• ag71xx_main.c (modified) (11 diffs)

trunk/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h

@@ -54 +54 @@
 #define AG71XX_RX_PKT_SIZE      \
         (ETH_FRAME_LEN + ETH_FCS_LEN + VLAN_HLEN)
+#define AG71XX_RX_BUF_SIZE (AG71XX_RX_PKT_SIZE + NET_SKB_PAD + NET_IP_ALIGN)
 
 #define AG71XX_TX_RING_SIZE_DEFAULT     64
@@ -86 +87 @@
 
 struct ag71xx_buf {
-        struct sk_buff          *skb;
+        union {
+                struct sk_buff  *skb;
+                void            *rx_buf;
+        };
         struct ag71xx_desc      *desc;
         dma_addr_t              dma_addr;

trunk/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c

@@ -190 +190 @@
 
         for (i = 0; i < ring->size; i++)
-                if (ring->buf[i].skb) {
+                if (ring->buf[i].rx_buf) {
                         dma_unmap_single(&ag->dev->dev, ring->buf[i].dma_addr,
-                                         AG71XX_RX_PKT_SIZE, DMA_FROM_DEVICE);
-                        kfree_skb(ring->buf[i].skb);
+                                         AG71XX_RX_BUF_SIZE, DMA_FROM_DEVICE);
+                        kfree(ring->buf[i].rx_buf);
                 }
 }
 
-struct sk_buff *ag71xx_rx_alloc(struct ag71xx *ag)
-{
+static int ag71xx_buffer_offset(struct ag71xx *ag)
+{
+        int offset = NET_SKB_PAD;
+
         /*
          * On AR71xx/AR91xx packets must be 4-byte aligned.
@@ -206 +208 @@
          */
         if (!ag71xx_get_pdata(ag)->is_ar724x || ag71xx_has_ar8216(ag))
-                return netdev_alloc_skb(ag->dev, AG71XX_RX_PKT_SIZE);
-
-        return netdev_alloc_skb_ip_align(ag->dev, AG71XX_RX_PKT_SIZE);
-}
-
+                return offset;
+
+        return offset + NET_IP_ALIGN;
+}
+
+static bool ag71xx_fill_rx_buf(struct ag71xx *ag, struct ag71xx_buf *buf,
+                               int offset)
+{
+        void *data;
+
+        data = kmalloc(AG71XX_RX_BUF_SIZE +
+                       SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
+                       GFP_ATOMIC);
+        if (!data)
+                return false;
+
+        buf->rx_buf = data;
+        buf->dma_addr = dma_map_single(&ag->dev->dev, data,
+                                       AG71XX_RX_BUF_SIZE, DMA_FROM_DEVICE);
+        buf->desc->data = (u32) buf->dma_addr + offset;
+        return true;
+}
 
 static int ag71xx_ring_rx_init(struct ag71xx *ag)
@@ -217 +236 @@
         unsigned int i;
         int ret;
+        int offset = ag71xx_buffer_offset(ag);
 
         ret = 0;
@@ -229 +249 @@
 
         for (i = 0; i < ring->size; i++) {
-                struct sk_buff *skb;
-                dma_addr_t dma_addr;
-
-                skb = ag71xx_rx_alloc(ag);
-                if (!skb) {
+                if (!ag71xx_fill_rx_buf(ag, &ring->buf[i], offset)) {
                         ret = -ENOMEM;
                         break;
                 }
 
-                skb->dev = ag->dev;
-                dma_addr = dma_map_single(&ag->dev->dev, skb->data,
-                                          AG71XX_RX_PKT_SIZE,
-                                          DMA_FROM_DEVICE);
-                ring->buf[i].skb = skb;
-                ring->buf[i].dma_addr = dma_addr;
-                ring->buf[i].desc->data = (u32) dma_addr;
                 ring->buf[i].desc->ctrl = DESC_EMPTY;
         }
@@ -261 +270 @@
         struct ag71xx_ring *ring = &ag->rx_ring;
         unsigned int count;
+        int offset = ag71xx_buffer_offset(ag);
 
         count = 0;
@@ -268 +278 @@
                 i = ring->dirty % ring->size;
 
-                if (ring->buf[i].skb == NULL) {
-                        dma_addr_t dma_addr;
-                        struct sk_buff *skb;
-
-                        skb = ag71xx_rx_alloc(ag);
-                        if (skb == NULL)
-                                break;
-
-                        skb->dev = ag->dev;
-
-                        dma_addr = dma_map_single(&ag->dev->dev, skb->data,
-                                                  AG71XX_RX_PKT_SIZE,
-                                                  DMA_FROM_DEVICE);
-
-                        ring->buf[i].skb = skb;
-                        ring->buf[i].dma_addr = dma_addr;
-                        ring->buf[i].desc->data = (u32) dma_addr;
-                }
+                if (!ring->buf[i].rx_buf &&
+                    !ag71xx_fill_rx_buf(ag, &ring->buf[i], offset))
+                        break;
 
                 ring->buf[i].desc->ctrl = DESC_EMPTY;
@@ -864 +859 @@
         struct net_device *dev = ag->dev;
         struct ag71xx_ring *ring = &ag->rx_ring;
+        int offset = ag71xx_buffer_offset(ag);
         int done = 0;
 
@@ -886 +882 @@
                 ag71xx_wr(ag, AG71XX_REG_RX_STATUS, RX_STATUS_PR);
 
-                skb = ring->buf[i].skb;
                 pktlen = ag71xx_desc_pktlen(desc);
                 pktlen -= ETH_FCS_LEN;
 
                 dma_unmap_single(&dev->dev, ring->buf[i].dma_addr,
-                                 AG71XX_RX_PKT_SIZE, DMA_FROM_DEVICE);
+                                 AG71XX_RX_BUF_SIZE, DMA_FROM_DEVICE);
 
                 dev->last_rx = jiffies;
@@ -897 +892 @@
                 dev->stats.rx_bytes += pktlen;
 
+                skb = build_skb(ring->buf[i].rx_buf);
+                if (!skb) {
+                        kfree(ring->buf[i].rx_buf);
+                        goto next;
+                }
+
+                skb_reserve(skb, offset);
                 skb_put(skb, pktlen);
+
                 if (ag71xx_has_ar8216(ag))
                         err = ag71xx_remove_ar8216_header(ag, skb, pktlen);
@@ -911 +914 @@
                 }
 
-                ring->buf[i].skb = NULL;
+next:
+                ring->buf[i].rx_buf = NULL;
                 done++;
 
@@ -945 +949 @@
 
         rx_ring = &ag->rx_ring;
-        if (rx_ring->buf[rx_ring->dirty % rx_ring->size].skb == NULL)
+        if (rx_ring->buf[rx_ring->dirty % rx_ring->size].rx_buf == NULL)
                 goto oom;