From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com] 

quoted

2015-12-21 10:38, Helin Zhang:

quoted

PCIe feature of 'Extended Tag' is important for 40G performance.
It adds its enabling during each port initialization, to ensure the
high performance.

If it's so important, why the values are not documented?
Please start to fill a file doc/guides/nics/i40e.rst to explain how the
device works. Thanks

It has already been mentioned in getting started guide for a long time.
Are you suggesting to move into i40e specifically? Thanks!

Yes you're right. I had forgotten that:
http://dpdk.org/doc/guides-2.2/linux_gsg/enable_func.html#enabling-extended-tag-and-setting-max-read-request-size

Yes, it would be better moved into an i40e doc.
And maybe max_read_request_size may be commented to give advices on values.
Thanks