Commit 9e2feace authored by Auke Kok's avatar Auke Kok
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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: default avatarJesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: default avatarAuke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: default avatarJohn Ronciak <john.ronciak@intel.com>
parent 6fc7a7ec

drivers/net/e1000/e1000.h

+2 −0
Original line number Diff line number Diff line
@@ -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

drivers/net/e1000/e1000_main.c

+50 −37
Original line number Diff line number Diff line
@@ -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) {

		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;
@@ -1622,7 +1629,6 @@ e1000_setup_rctl(struct e1000_adapter *adapter) 
			rctl |= E1000_RCTL_SZ_16384;

			break;

	}

	}



#ifndef CONFIG_E1000_DISABLE_PACKET_SPLIT

	/* 82571 and greater support packet-split where the protocol
@@ -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;
@@ -3017,18 +3022,18 @@ e1000_change_mtu(struct net_device *netdev, int new_mtu) 
		break;

	}



	/* 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 (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)

	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;
@@ -3036,8 +3041,13 @@ e1000_change_mtu(struct net_device *netdev, int new_mtu) 
		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

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