On Fri, 22 Sep 2006 22:25:07 -0700 (PDT)
David Miller <[EMAIL PROTECTED]> wrote:
> From: Andrew Morton <[EMAIL PROTECTED]>
> Date: Fri, 22 Sep 2006 21:50:00 -0700
>
> > On Fri, 22 Sep 2006 10:10:36 -0700
> > Auke Kok <[EMAIL PROTECTED]> wrote:
> >
> > > e1000: account for NET_IP_ALIGN when calculating bufsiz
> > >
> > > Account for NET_IP_ALIGN when requesting buffer sizes from
> > > netdev_alloc_skb to
> > > reduce slab allocation by half.
> >
> > Could we please do whatever is needed to get this blessed and merged? This
> > 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.
>
> The NET_IP_ALIGN existed not just for fun :) There are ramifications
> 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];
_
-
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