netdev - Re: [PATCH 1/4] ibmveth: Enable TCP checksum offload

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Date:	Thu, 19 Jul 2007 08:35:14 -0500
From:	Brian King <brking@...ux.vnet.ibm.com>
To:	Jeff Garzik <jeff@...zik.org>
CC:	linuxppc-dev@...abs.org, rcjenn@...ux.vnet.ibm.com,
	santil@...ux.vnet.ibm.com, netdev@...r.kernel.org
Subject: Re: [PATCH 1/4] ibmveth: Enable TCP checksum offload

Jeff Garzik wrote:
> Brian King wrote:
>> This patchset enables TCP checksum offload support for IPV4
>> on ibmveth. This completely eliminates the generation and checking of
>> the checksum for packets that are completely virtual and never
>> touch a physical network. A simple TCP_STREAM netperf run on
>> a virtual network with maximum mtu set yielded a ~30% increase
>> in throughput. This feature is enabled by default on systems that
>> support it, but can be disabled with a module option.
>>
>> Signed-off-by: Brian King <brking@...ux.vnet.ibm.com>
> 
> this should be controllable purely via ethtool...

I'll remove the module parameter and resend.

>>  struct ibmveth_rx_q_entry {
>>      u16 toggle : 1;
>>      u16 valid : 1;
>> -    u16 reserved : 14;
>> +    u16 reserved : 4;
>> +    u16 no_csum : 1;
>> +    u16 csum_good : 1;
>> +    u16 reserved2 : 8;
>>      u16 offset;
> 
> As a general rule, it would be nice to start moving away from bitfields 
> in this driver

I'll take a look at that for a future cleanup patch.

Thanks,

Brian

-- 
Brian King
Linux on Power Virtualization
IBM Linux Technology Center
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