Re: + e1000-account-for-net_ip_align-when-calculating-bufsiz.patchadded to -mm tree

[Auke Kok]

akpm@xxxxxxxx wrote:
> The patch titled
>
>      e1000: account for NET_IP_ALIGN when calculating bufsiz
>
> has been added to the -mm tree.  Its filename is
>
>      e1000-account-for-net_ip_align-when-calculating-bufsiz.patch
>
> See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
> out what to do about this


Andrew,

can you drop this patch? Discussion and testing showed that it does the reverse 
of what it needs to be for the cornercases and doesn't fix anything.

old case 255 max_frame -> 256 buffer -> 512 slab
this patch 255 max_frame -> 512 buffer -> 1024 slab (!)

Thanks,

Auke


> ------------------------------------------------------
> Subject: e1000: account for NET_IP_ALIGN when calculating bufsiz
> From: Auke Kok <auke-jan.h.kok@xxxxxxxxx>
>
> Account for NET_IP_ALIGN when requesting buffer sizes from netdev_alloc_skb
> to reduce slab allocation by half.
>
> Signed-off-by: Auke Kok <auke-jan.h.kok@xxxxxxxxx>
> Cc: Jeff Garzik <jeff@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
> ---
>
>  drivers/net/e1000/e1000_main.c |   22 ++++++++++++----------
>  1 file changed, 12 insertions(+), 10 deletions(-)
>
> 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];
> _
>
> Patches currently in -mm which might be from auke-jan.h.kok@xxxxxxxxx are
>
> git-netdev-all.patch
> e1000-memory-leak-in-e1000_set_ringparam.patch
> e1000-account-for-net_ip_align-when-calculating-bufsiz.patch
> e1000_7033_dump_ring.patch
>
> -
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