Messages in this thread | | | Date | Sun, 24 Sep 2006 14:15:42 -0700 | From | Auke Kok <> | Subject | Re: 2.6.1[78] page allocation failure. order:3, mode:0x20 |
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Evgeniy Polyakov wrote: > On Fri, Sep 22, 2006 at 10:33:48PM -0700, Andrew Morton (akpm@osdl.org) wrote: >>> 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. > > This patch will not help - netdev_alloc_skb() adds additional > NET_SKB_PAD and then alloc_skb() adds sizeof(struct skb_shared_info). > And even if you acconut for them in adapter->rx_buf_len, chip still can > overwrite that area (in the thread mentioned in this e-mail thread > before I posted such patch and received a dump of sizes chip receives - > there were a lot of _different_ ones which were too close to the limit).
I just did the math on it and it does not compute as I wanted too, we're basically flowing to the next larger buffersize 2 mtu bytes earlier, undoing any benefit completely.
There is not much that can fix this issue since the hardware will always receive in 2-order buffers and dma that back in its entirity, so we must always claim size for NET_IP_ALIGN and NET_SKB_PAD after the 2-order bufsz. For the 9kb mtu case (16kb hw bufsz), we're stuck with 32kb slab allocations. bummer.
Andrew, please drop this patch.
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]; >> _ >> >> - >> To unsubscribe from this list: send the line "unsubscribe netdev" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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