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SubjectRe: 2.6.1[78] page allocation failure. order:3, mode:0x20
Andrew Morton wrote:
> On Fri, 22 Sep 2006 22:25:07 -0700 (PDT)
> David Miller <davem@davemloft.net> wrote:
>
>> From: Andrew Morton <akpm@osdl.org>
>> Date: Fri, 22 Sep 2006 21:50:00 -0700
>>
>>> On Fri, 22 Sep 2006 10:10:36 -0700
>>> Auke Kok <auke-jan.h.kok@intel.com> 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.

yes, the only thing I'm doing is accounting for the 2 bytes one steap earlier.
It works fine for the general case and I tested it too, but I am not too sure
about the corner cases as the hardware has no notion of mtu at all and could
possibly overwrite by two bytes. I think my patch actually give the hardware
two bytes too much now, so we're on the other side (safe) of that problem, but
I have to verify this first of course.

I'll be wrestling this on monday with Jesse and try to nail it down.

Auke

>
>
> 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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