[dpdk-dev] about rx checksum flags

Olivier Matz olivier.matz at 6wind.com
Fri Jun 3 14:43:08 CEST 2016


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.


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