ixgb: add performance enhancements to the buffer_info struct

o modify the rx refill logic and tail bump
o add counter for failures

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: John Ronciak <john.ronciak@intel.com>

diff --git a/drivers/net/ixgb/ixgb.h b/drivers/net/ixgb/ixgb.h
index b9c37fd..bdbaf5a 100644 (file)
--- a/drivers/net/ixgb/ixgb.h
+++ b/drivers/net/ixgb/ixgb.h
@@ -200,6 +200,7 @@ struct ixgb_adapter {
        struct ixgb_hw hw;
        u16 msg_enable;
        struct ixgb_hw_stats stats;
+       uint32_t alloc_rx_buff_failed;
 #ifdef CONFIG_PCI_MSI
        boolean_t have_msi;
 #endif

diff --git a/drivers/net/ixgb/ixgb_main.c b/drivers/net/ixgb/ixgb_main.c
index 0905a82..27034b3 100644 (file)
--- a/drivers/net/ixgb/ixgb_main.c
+++ b/drivers/net/ixgb/ixgb_main.c
@@ -929,17 +929,20 @@ ixgb_unmap_and_free_tx_resource(struct ixgb_adapter *adapter,
                                        struct ixgb_buffer *buffer_info)
 {
        struct pci_dev *pdev = adapter->pdev;
-       if(buffer_info->dma) {
-               pci_unmap_page(pdev,
-                          buffer_info->dma,
-                          buffer_info->length,
-                          PCI_DMA_TODEVICE);
-               buffer_info->dma = 0;
-       }
-       if(buffer_info->skb) {
+
+       if (buffer_info->dma)
+               pci_unmap_page(pdev, buffer_info->dma, buffer_info->length,
+                              PCI_DMA_TODEVICE);
+
+       if (buffer_info->skb)
                dev_kfree_skb_any(buffer_info->skb);
-               buffer_info->skb = NULL;
-       }
+
+       buffer_info->skb = NULL;
+       buffer_info->dma = 0;
+       buffer_info->time_stamp = 0;
+       /* these fields must always be initialized in tx
+        * buffer_info->length = 0;
+        * buffer_info->next_to_watch = 0; */
 }
 
 /**
@@ -1314,6 +1317,7 @@ ixgb_tx_map(struct ixgb_adapter *adapter, struct sk_buff *skb,
                                size,
                                PCI_DMA_TODEVICE);
                buffer_info->time_stamp = jiffies;
+               buffer_info->next_to_watch = 0;
 
                len -= size;
                offset += size;
@@ -1345,6 +1349,7 @@ ixgb_tx_map(struct ixgb_adapter *adapter, struct sk_buff *skb,
                                        size,
                                        PCI_DMA_TODEVICE);
                        buffer_info->time_stamp = jiffies;
+                       buffer_info->next_to_watch = 0;
 
                        len -= size;
                        offset += size;
@@ -1940,6 +1945,7 @@ ixgb_clean_rx_irq(struct ixgb_adapter *adapter)
 #endif
                status = rx_desc->status;
                skb = buffer_info->skb;
+               buffer_info->skb = NULL;
 
                prefetch(skb->data);
 
@@ -2013,7 +2019,6 @@ ixgb_clean_rx_irq(struct ixgb_adapter *adapter)
 rxdesc_done:
                /* clean up descriptor, might be written over by hw */
                rx_desc->status = 0;
-               buffer_info->skb = NULL;
 
                /* use prefetched values */
                rx_desc = next_rxd;
@@ -2053,12 +2058,18 @@ ixgb_alloc_rx_buffers(struct ixgb_adapter *adapter)
 
        /* leave three descriptors unused */
        while(--cleancount > 2) {
-               rx_desc = IXGB_RX_DESC(*rx_ring, i);
-
-               skb = dev_alloc_skb(adapter->rx_buffer_len + NET_IP_ALIGN);
+               /* recycle! its good for you */
+               if (!(skb = buffer_info->skb))
+                       skb = dev_alloc_skb(adapter->rx_buffer_len
+                                           + NET_IP_ALIGN);
+               else {
+                       skb_trim(skb, 0);
+                       goto map_skb;
+               }
 
-               if(unlikely(!skb)) {
+               if (unlikely(!skb)) {
                        /* Better luck next round */
+                       adapter->alloc_rx_buff_failed++;
                        break;
                }
 
@@ -2072,33 +2083,36 @@ ixgb_alloc_rx_buffers(struct ixgb_adapter *adapter)
 
                buffer_info->skb = skb;
                buffer_info->length = adapter->rx_buffer_len;
-               buffer_info->dma =
-                       pci_map_single(pdev,
-                                  skb->data,
-                                  adapter->rx_buffer_len,
-                                  PCI_DMA_FROMDEVICE);
+map_skb:
+               buffer_info->dma = pci_map_single(pdev,
+                                                 skb->data,
+                                                 adapter->rx_buffer_len,
+                                                 PCI_DMA_FROMDEVICE);
 
+               rx_desc = IXGB_RX_DESC(*rx_ring, i);
                rx_desc->buff_addr = cpu_to_le64(buffer_info->dma);
                /* guarantee DD bit not set now before h/w gets descriptor
                 * this is the rest of the workaround for h/w double 
                 * writeback. */
                rx_desc->status = 0;
 
-               if((i & ~(num_group_tail_writes- 1)) == i) {
-                       /* Force memory writes to complete before letting h/w
-                        * know there are new descriptors to fetch.  (Only
-                        * applicable for weak-ordered memory model archs,
-                        * such as IA-64). */
-                       wmb();
-
-                       IXGB_WRITE_REG(&adapter->hw, RDT, i);
-               }
 
                if(++i == rx_ring->count) i = 0;
                buffer_info = &rx_ring->buffer_info[i];
        }
 
-       rx_ring->next_to_use = i;
+       if (likely(rx_ring->next_to_use != i)) {
+               rx_ring->next_to_use = i;
+               if (unlikely(i-- == 0))
+                       i = (rx_ring->count - 1);
+
+               /* Force memory writes to complete before letting h/w
+                * know there are new descriptors to fetch.  (Only
+                * applicable for weak-ordered memory model archs, such
+                * as IA-64). */
+               wmb();
+               IXGB_WRITE_REG(&adapter->hw, RDT, i);
+       }
 }
 
 /**