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To: "Chandran, Sugesh" <sugesh.chandran@intel.com>,
 "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
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Cc: Yuanhan Liu <yuanhan.liu@linux.intel.com>, "dev@dpdk.org" <dev@dpdk.org>, 
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From: Olivier Matz <olivier.matz@6wind.com>
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Date: Fri, 3 Jun 2016 14:43:08 +0200
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Subject: Re: [dpdk-dev] about rx checksum flags
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Hi,

On 06/02/2016 09:42 AM, Chandran, Sugesh wrote:
>>>> Do you also suggest to drop IP checksum flags?
>>> > >
>>> > > IP checksum offload is mostly useless. If application needs to look at
>>> > > IP, it can do whole checksum in very few instructions, the whole
>>> > > header is in the same cache line as src/dst so the HW offload is really no
>> > help.
>>> > >
> [Sugesh] The checksum offload can boost the tunneling performance in OVS.
> I guess the IP checksum also important as L4. In some cases, UDP checksum is
> zero and no need to validate it. But Ip checksum is present on all the packets and that must be
> validated all  the time. At higher packet rate, the ip checksum offload can offer slight 
> performance improvement. What do you think??
> 

Agree, in some situations (and this is even more true with packet
types / smartnics), the application could process without accessing
the packet data if we keep the IP cksum flags.

Regards,
Olivier