On Fri, 22 Sep 2006 22:25:07 -0700 (PDT)
David Miller <davem@xxxxxxxxxxxxx> wrote:
From: Andrew Morton <akpm@xxxxxxxx>
Date: Fri, 22 Sep 2006 21:50:00 -0700
On Fri, 22 Sep 2006 10:10:36 -0700The NET_IP_ALIGN existed not just for fun :) There are ramifications
Auke Kok <auke-jan.h.kok@xxxxxxxxx> wrote:
e1000: account for NET_IP_ALIGN when calculating bufsizCould we please do whatever is needed to get this blessed and merged? This
Account for NET_IP_ALIGN when requesting buffer sizes from netdev_alloc_skb to reduce slab allocation by half.
is such a common problem on such a common driver that I would suggest that
we want this in 2.6.18.x as well. At least, I'd expect distributors to
ship this fix (they're nuts if they don't) and so it makes sense to deliver
it from kernel.org.
for removing it.
It's still there, isn't it?
For the 9k MTU case, for example, we end up allocating 16384 byte skbs
instead of 32786 kbytes ones.
-
diff -puN drivers/net/e1000/e1000_main.c~e1000-account-for-net_ip_align-when-calculating-bufsiz drivers/net/e1000/e1000_main.c
--- a/drivers/net/e1000/e1000_main.c~e1000-account-for-net_ip_align-when-calculating-bufsiz
+++ a/drivers/net/e1000/e1000_main.c
@@ -1101,7 +1101,7 @@ e1000_sw_init(struct e1000_adapter *adap
pci_read_config_word(pdev, PCI_COMMAND, &hw->pci_cmd_word);
- adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE;
+ adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE + NET_IP_ALIGN;
adapter->rx_ps_bsize0 = E1000_RXBUFFER_128;
hw->max_frame_size = netdev->mtu +
ENET_HEADER_SIZE + ETHERNET_FCS_SIZE;
@@ -3163,26 +3163,27 @@ e1000_change_mtu(struct net_device *netd
* larger slab size
* i.e. RXBUFFER_2048 --> size-4096 slab */
- if (max_frame <= E1000_RXBUFFER_256)
+ if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_256)
adapter->rx_buffer_len = E1000_RXBUFFER_256;
- else if (max_frame <= E1000_RXBUFFER_512)
+ else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_512)
adapter->rx_buffer_len = E1000_RXBUFFER_512;
- else if (max_frame <= E1000_RXBUFFER_1024)
+ else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_1024)
adapter->rx_buffer_len = E1000_RXBUFFER_1024;
- else if (max_frame <= E1000_RXBUFFER_2048)
+ else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_2048)
adapter->rx_buffer_len = E1000_RXBUFFER_2048;
- else if (max_frame <= E1000_RXBUFFER_4096)
+ else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_4096)
adapter->rx_buffer_len = E1000_RXBUFFER_4096;
- else if (max_frame <= E1000_RXBUFFER_8192)
+ else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_8192)
adapter->rx_buffer_len = E1000_RXBUFFER_8192;
- else if (max_frame <= E1000_RXBUFFER_16384)
+ else
adapter->rx_buffer_len = E1000_RXBUFFER_16384;
/* adjust allocation if LPE protects us, and we aren't using SBP */
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;
+ adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE +
+ NET_IP_ALIGN;
netdev->mtu = new_mtu;
@@ -4002,7 +4003,8 @@ e1000_alloc_rx_buffers(struct e1000_adap
struct e1000_buffer *buffer_info;
struct sk_buff *skb;
unsigned int i;
- unsigned int bufsz = adapter->rx_buffer_len + NET_IP_ALIGN;
+ /* we have already accounted for NET_IP_ALIGN */
+ unsigned int bufsz = adapter->rx_buffer_len;
i = rx_ring->next_to_use;
buffer_info = &rx_ring->buffer_info[i];
_