e1000: Buffer optimizations for small MTU

Remove multi-descriptor support from legacy recieve path

Add memory usage efficiency by using more correct size descriptors for
small MTU sizes and optimize using LPE for <= 1522 byte frame sizes

An extra performance fix that effected our TCP window size growth
as a receiver.  Set our initial buffer to be 128 bytes instead of 256
to prevent over-socket charge when truesize is computed in the stack.
old way: truesize = 256 + l1 = 256 + 1460 = 1716
new way: truesize = 128 + l1 = 128 + 1460 = 1588
The magic value that we can't cross is 1648.

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/e1000/e1000.h b/drivers/net/e1000/e1000.h
index 764808f3702ec269f61dcb874932e391f66227d2..2dfabdb29e7b47b1fd5f40ca04ae02ceaad6951a 100644 (file)
--- a/drivers/net/e1000/e1000.h
+++ b/drivers/net/e1000/e1000.h
@@ -114,6 +114,8 @@ struct e1000_adapter;
 /* Supported Rx Buffer Sizes */
 #define E1000_RXBUFFER_128   128    /* Used for packet split */
 #define E1000_RXBUFFER_256   256    /* Used for packet split */
+#define E1000_RXBUFFER_512   512
+#define E1000_RXBUFFER_1024  1024
 #define E1000_RXBUFFER_2048  2048
 #define E1000_RXBUFFER_4096  4096
 #define E1000_RXBUFFER_8192  8192

diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index 6d7ba0bb233af73181994ed3ef2578f3efe5c8f6..f604a1dea399de77c697b8ffc6aef71b04837a61 100644 (file)
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -972,8 +972,8 @@ e1000_sw_init(struct e1000_adapter *adapter)
 
        pci_read_config_word(pdev, PCI_COMMAND, &hw->pci_cmd_word);
 
-       adapter->rx_buffer_len = E1000_RXBUFFER_2048;
-       adapter->rx_ps_bsize0 = E1000_RXBUFFER_256;
+       adapter->rx_buffer_len = MAXIMUM_ETHERNET_FRAME_SIZE;
+       adapter->rx_ps_bsize0 = E1000_RXBUFFER_128;
        hw->max_frame_size = netdev->mtu +
                             ENET_HEADER_SIZE + ETHERNET_FCS_SIZE;
        hw->min_frame_size = MINIMUM_ETHERNET_FRAME_SIZE;
@@ -1599,14 +1599,21 @@ e1000_setup_rctl(struct e1000_adapter *adapter)
                rctl |= E1000_RCTL_LPE;
 
        /* Setup buffer sizes */
-       if (adapter->hw.mac_type >= e1000_82571) {
-               /* We can now specify buffers in 1K increments.
-                * BSIZE and BSEX are ignored in this case. */
-               rctl |= adapter->rx_buffer_len << 0x11;
-       } else {
-               rctl &= ~E1000_RCTL_SZ_4096;
-               rctl |= E1000_RCTL_BSEX; 
-               switch (adapter->rx_buffer_len) {
+       rctl &= ~E1000_RCTL_SZ_4096;
+       rctl |= E1000_RCTL_BSEX;
+       switch (adapter->rx_buffer_len) {
+               case E1000_RXBUFFER_256:
+                       rctl |= E1000_RCTL_SZ_256;
+                       rctl &= ~E1000_RCTL_BSEX;
+                       break;
+               case E1000_RXBUFFER_512:
+                       rctl |= E1000_RCTL_SZ_512;
+                       rctl &= ~E1000_RCTL_BSEX;
+                       break;
+               case E1000_RXBUFFER_1024:
+                       rctl |= E1000_RCTL_SZ_1024;
+                       rctl &= ~E1000_RCTL_BSEX;
+                       break;
                case E1000_RXBUFFER_2048:
                default:
                        rctl |= E1000_RCTL_SZ_2048;
@@ -1621,7 +1628,6 @@ e1000_setup_rctl(struct e1000_adapter *adapter)
                case E1000_RXBUFFER_16384:
                        rctl |= E1000_RCTL_SZ_16384;
                        break;
-               }
        }
 
 #ifndef CONFIG_E1000_DISABLE_PACKET_SPLIT
@@ -2982,8 +2988,7 @@ e1000_change_mtu(struct net_device *netdev, int new_mtu)
 
        /* Adapter-specific max frame size limits. */
        switch (adapter->hw.mac_type) {
-       case e1000_82542_rev2_0:
-       case e1000_82542_rev2_1:
+       case e1000_undefined ... e1000_82542_rev2_1:
                if (max_frame > MAXIMUM_ETHERNET_FRAME_SIZE) {
                        DPRINTK(PROBE, ERR, "Jumbo Frames not supported.\n");
                        return -EINVAL;
@@ -3017,27 +3022,32 @@ e1000_change_mtu(struct net_device *netdev, int new_mtu)
                break;
        }
 
-
-       if (adapter->hw.mac_type > e1000_82547_rev_2) {
-               adapter->rx_buffer_len = max_frame;
-               E1000_ROUNDUP(adapter->rx_buffer_len, 1024);
-       } else {
-               if(unlikely((adapter->hw.mac_type < e1000_82543) &&
-                  (max_frame > MAXIMUM_ETHERNET_FRAME_SIZE))) {
-                       DPRINTK(PROBE, ERR, "Jumbo Frames not supported "
-                                           "on 82542\n");
-                       return -EINVAL;
-               } else {
-                       if(max_frame <= E1000_RXBUFFER_2048)
-                               adapter->rx_buffer_len = E1000_RXBUFFER_2048;
-                       else if(max_frame <= E1000_RXBUFFER_4096)
-                               adapter->rx_buffer_len = E1000_RXBUFFER_4096;
-                       else if(max_frame <= E1000_RXBUFFER_8192)
-                               adapter->rx_buffer_len = E1000_RXBUFFER_8192;
-                       else if(max_frame <= E1000_RXBUFFER_16384)
-                               adapter->rx_buffer_len = E1000_RXBUFFER_16384;
-               }
-       }
+       /* NOTE: dev_alloc_skb reserves 16 bytes, and typically NET_IP_ALIGN
+        * means we reserve 2 more, this pushes us to allocate from the next
+        * larger slab size
+        * i.e. RXBUFFER_2048 --> size-4096 slab */
+
+       if (max_frame <= E1000_RXBUFFER_256)
+               adapter->rx_buffer_len = E1000_RXBUFFER_256;
+       else if (max_frame <= E1000_RXBUFFER_512)
+               adapter->rx_buffer_len = E1000_RXBUFFER_512;
+       else if (max_frame <= E1000_RXBUFFER_1024)
+               adapter->rx_buffer_len = E1000_RXBUFFER_1024;
+       else if (max_frame <= E1000_RXBUFFER_2048)
+               adapter->rx_buffer_len = E1000_RXBUFFER_2048;
+       else if (max_frame <= E1000_RXBUFFER_4096)
+               adapter->rx_buffer_len = E1000_RXBUFFER_4096;
+       else if (max_frame <= E1000_RXBUFFER_8192)
+               adapter->rx_buffer_len = E1000_RXBUFFER_8192;
+       else if (max_frame <= E1000_RXBUFFER_16384)
+               adapter->rx_buffer_len = E1000_RXBUFFER_16384;
+
+       /* adjust allocation if LPE protects us, and we aren't using SBP */
+#define MAXIMUM_ETHERNET_VLAN_SIZE 1522
+       if (!adapter->hw.tbi_compatibility_on &&
+           ((max_frame == MAXIMUM_ETHERNET_FRAME_SIZE) ||
+            (max_frame == MAXIMUM_ETHERNET_VLAN_SIZE)))
+               adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE;
 
        netdev->mtu = new_mtu;
 
@@ -3568,10 +3578,12 @@ e1000_clean_rx_irq(struct e1000_adapter *adapter,
                                                       flags);
                                length--;
                        } else {
-                               dev_kfree_skb_irq(skb);
+                               /* recycle */
+                               buffer_info->skb = skb;
                                goto next_desc;
                        }
-               }
+               } else
+                       skb_put(skb, length);
 
                /* code added for copybreak, this should improve
                 * performance for small packets with large amounts
@@ -3676,6 +3688,7 @@ e1000_clean_rx_irq_ps(struct e1000_adapter *adapter,
        i = rx_ring->next_to_clean;
        rx_desc = E1000_RX_DESC_PS(*rx_ring, i);
        staterr = le32_to_cpu(rx_desc->wb.middle.status_error);
+       buffer_info = &rx_ring->buffer_info[i];
 
        while (staterr & E1000_RXD_STAT_DD) {
                buffer_info = &rx_ring->buffer_info[i];
@@ -3736,7 +3749,7 @@ e1000_clean_rx_irq_ps(struct e1000_adapter *adapter,
 
                /* page alloc/put takes too long and effects small packet
                 * throughput, so unsplit small packets and save the alloc/put*/
-               if (l1 && ((length + l1) < E1000_CB_LENGTH)) {
+               if (l1 && ((length + l1) <= adapter->rx_ps_bsize0)) {
                        u8 *vaddr;
                        /* there is no documentation about how to call 
                         * kmap_atomic, so we can't hold the mapping