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On Thu, Sep 06, 2001 at 01:17:57PM +0200, P=E5l Halvorsen wrote:
>=20
> If we assume using NIC DMA to access main memory and using UDP/IP
> calculating UDP checksum, filling the IP header and caclulating IP header
> checksum.
>=20
> Does this mean that the checksum offload requires more bus transfers than
> native checksum mechanisms only transfering the original packet once?
> (data and UDP header twice, and IP header three times - including the
> UDPIP pseudo header used during UDP checksum)=20
> Or is the data transfered to the NIC during UDP checksum and only the
> headers are transfered several times?

There is a third option. Never return the checksum to the cpu's main memory.

I don't know what is implemented by the hardware & driver in question, but
you can easily check that yourself.

	-is

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