[PATCH] e1000: Added copy break code

Improves small packet performance with large amounts of reassembly being done in the stack.

Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: John Ronciak <john.ronciak@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

1 files changed, 47 insertions, 12 deletions

diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index 8207db44b705..bef4d9d6f2d5 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -420,7 +420,8 @@ e1000_up(struct e1000_adapter *adapter)
          * next_to_use != next_to_clean */
         for (i = 0; i < adapter->num_rx_queues; i++) {
                 struct e1000_rx_ring *ring = &adapter->rx_ring[i];
-                adapter->alloc_rx_buf(adapter, ring, E1000_DESC_UNUSED(ring));
+                adapter->alloc_rx_buf(adapter, ring,
+                                      E1000_DESC_UNUSED(ring));
         }
 
 #ifdef CONFIG_PCI_MSI
@@ -3567,23 +3568,26 @@ e1000_clean_rx_irq(struct e1000_adapter *adapter,
         uint32_t length;
         uint8_t last_byte;
         unsigned int i;
-        boolean_t cleaned = FALSE;
         int cleaned_count = 0;
+        boolean_t cleaned = FALSE, multi_descriptor = FALSE;
 
         i = rx_ring->next_to_clean;
         rx_desc = E1000_RX_DESC(*rx_ring, i);
 
         while(rx_desc->status & E1000_RXD_STAT_DD) {
                 buffer_info = &rx_ring->buffer_info[i];
+                u8 status;
 #ifdef CONFIG_E1000_NAPI
                 if(*work_done >= work_to_do)
                         break;
                 (*work_done)++;
 #endif
-
+                status = rx_desc->status;
                 cleaned = TRUE;
                 cleaned_count++;
-                pci_unmap_single(pdev, buffer_info->dma, buffer_info->length,
+                pci_unmap_single(pdev,
+                                 buffer_info->dma,
+                                 buffer_info->length,
                                  PCI_DMA_FROMDEVICE);
 
                 skb = buffer_info->skb;
@@ -3602,7 +3606,8 @@ e1000_clean_rx_irq(struct e1000_adapter *adapter,
                         if(TBI_ACCEPT(&adapter->hw, rx_desc->status,
                                       rx_desc->errors, length, last_byte)) {
                                 spin_lock_irqsave(&adapter->stats_lock, flags);
-                                e1000_tbi_adjust_stats(&adapter->hw, &adapter->stats,
+                                e1000_tbi_adjust_stats(&adapter->hw,
+                                                       &adapter->stats,
                                                        length, skb->data);
                                 spin_unlock_irqrestore(&adapter->stats_lock,
                                                        flags);
@@ -3613,17 +3618,40 @@ e1000_clean_rx_irq(struct e1000_adapter *adapter,
                         }
                 }
 
-                /* Good Receive */
-                skb_put(skb, length - ETHERNET_FCS_SIZE);
+                /* code added for copybreak, this should improve
+                 * performance for small packets with large amounts
+                 * of reassembly being done in the stack */
+#define E1000_CB_LENGTH 256
+                if ((length < E1000_CB_LENGTH) &&
+                   !rx_ring->rx_skb_top &&
+                   /* or maybe (status & E1000_RXD_STAT_EOP) && */
+                   !multi_descriptor) {
+                        struct sk_buff *new_skb =
+                            dev_alloc_skb(length + NET_IP_ALIGN);
+                        if (new_skb) {
+                                skb_reserve(new_skb, NET_IP_ALIGN);
+                                new_skb->dev = netdev;
+                                memcpy(new_skb->data - NET_IP_ALIGN,
+                                       skb->data - NET_IP_ALIGN,
+                                       length + NET_IP_ALIGN);
+                                /* save the skb in buffer_info as good */
+                                buffer_info->skb = skb;
+                                skb = new_skb;
+                                skb_put(skb, length);
+                        }
+                }
+
+                /* end copybreak code */
 
                 /* Receive Checksum Offload */
-                e1000_rx_checksum(adapter, (uint32_t)(rx_desc->status) |
+                e1000_rx_checksum(adapter,
+                                  (uint32_t)(status) |
                                   ((uint32_t)(rx_desc->errors) << 24),
                                   rx_desc->csum, skb);
                 skb->protocol = eth_type_trans(skb, netdev);
 #ifdef CONFIG_E1000_NAPI
                 if(unlikely(adapter->vlgrp &&
-                            (rx_desc->status & E1000_RXD_STAT_VP))) {
+                            (status & E1000_RXD_STAT_VP))) {
                         vlan_hwaccel_receive_skb(skb, adapter->vlgrp,
                                                  le16_to_cpu(rx_desc->special) &
                                                  E1000_RXD_SPC_VLAN_MASK);
@@ -3817,7 +3845,7 @@ next_desc:
 static void
 e1000_alloc_rx_buffers(struct e1000_adapter *adapter,
                        struct e1000_rx_ring *rx_ring,
-                       int cleaned_count)
+                       int cleaned_count)
 {
         struct net_device *netdev = adapter->netdev;
         struct pci_dev *pdev = adapter->pdev;
@@ -3830,8 +3858,14 @@ e1000_alloc_rx_buffers(struct e1000_adapter *adapter,
         i = rx_ring->next_to_use;
         buffer_info = &rx_ring->buffer_info[i];
 
-        while(!buffer_info->skb) {
-                skb = dev_alloc_skb(bufsz);
+        while (cleaned_count--) {
+                if (!(skb = buffer_info->skb))
+                        skb = dev_alloc_skb(bufsz);
+                else {
+                        skb_trim(skb, 0);
+                        goto map_skb;
+                }
+
 
                 if(unlikely(!skb)) {
                         /* Better luck next round */
@@ -3872,6 +3906,7 @@ e1000_alloc_rx_buffers(struct e1000_adapter *adapter,
 
                 buffer_info->skb = skb;
                 buffer_info->length = adapter->rx_buffer_len;
+map_skb:
                 buffer_info->dma = pci_map_single(pdev,
                                                   skb->data,
                                                   adapter->rx_buffer_len,