On Tue, Aug 6, 2013 at 8:22 PM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
> On Tue, 2013-08-06 at 08:52 +0800, Ming Lei wrote:
>> This patch enables 'can_dma_sg' flag for ax88179_178a device
>> if the attached host controller supports building packet from
>> discontinuous buffers(DMA SG is possible), so TSO can be enabled
>> and skb fragment buffers can be passed to usb stack via urb->sg
>> directly.
>>
>> With the patch, system CPU utilization decreased ~50% and throughput
>> increased by ~10% when doing iperf client test on one ARM A15 dual
>> core board.
>>
>
> Nice ;)
>
>> AX_RXCOE_TCPV6 | AX_RXCOE_UDPV6;
>> @@ -1310,6 +1318,10 @@ static int ax88179_reset(struct usbnet *dev)
>>
>> dev->net->hw_features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
>> NETIF_F_RXCSUM;
>> + if (dev->can_dma_sg) {
>> + dev->net->features |= NETIF_F_SG | NETIF_F_TSO;
>> + dev->net->hw_features |= NETIF_F_SG | NETIF_F_TSO;
>> + }
>>
>
> My concern with setting TSO on reset() is the following :
>
> Admin can disable TSO with
>
> ethtool -K ethX tso off
>
>
> Then, one hour later, or one month later, a reset happens, and this code
> magically re-enables TSO
The reset only happens during open(), and TSO can't be re-enabled magically,
unless the interface is re-opened by Admin.
>
> So, I really think this part should be removed from your patch.
OK, will remove it.
Thanks,
--
Ming Lei
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