Todd,
The history of the ticket 8001197134 gave the problem statement. The
Linux TCP/IP stack is receiving out of order packets delivery from even when
the two host with Intel XL710 40 GE are connected directly back to back. The
out of order packets triggers receiver side TCP/IP DUP ACK and cause the sender
to go into fast retransmit state and kills throughput performance (especially
as the end application of the 40GE is data transfer over 100Gbps WAN
connections). The Dell R620 servers are connected via two Intel E40GQSFPSR
transceivers with a Tripp Lite N844-10M-12-P40GBase-SR4 MPO cable back-to-back.
Intel customer support doesn't think re-transmits dramatically impact
throughput, alluding to improper socket buffering, and stated that out of order
packets are counted in different statistics. Intel customer support did not
provide any numbers as what "dramatically impact" means nor how they are
looking for socket buffering or out of order statistics. What does Intel expect
in terms of XL710 throughput performance, how do you check for Intel NIC socket
buffering settings, and what out of order statistics?
Comparing "ethtool -S i40e1" before and after the iperf3 run does indicate
multiple tx changes. Iperf3 was configured to run as a single thread, we
expected the Intel NIC to handle a single flow in a single queue and not spread
around over multiple queues. Can you explain the design why scheduling would
impact a single flow?
We are also seeing similar behavior from Intel 10GE NIC in production across
WAN links while other vendor's hardware do not exhibit this Out-Of-Order packet
deliver.
-----Original Message-----
From: Fujinaka, Todd [mailto:[email protected]]
Sent: Wednesday, July 22, 2015 11:25 AM
To: Hu, Tan Chang; [email protected]
Cc: Naegle, John H
Subject: [EXTERNAL] RE: [E1000-devel] Intel Customer Support Service Request
Management request # 8001197134
Can you restate your problem so we can start over on this issue? You may want
to just start with a new subject line as well. From what I've heard from
customer service, there was no issue and the case was closed but I haven't
heard all the details at this time.
Another way to get help is to escalate this through your factory contact
(whoever sold you whatever it is you're having problems with) and they can file
a ticket in IPS.
My suggestion is to start over here with a problem statement and we can ask you
for more details as we go. I'd also suggest filing a bug on sourceforge if you
have attachments to send (inline in email is hard to read), but sourceforge is
having issues at the moment.
Todd Fujinaka
Software Application Engineer
Networking Division (ND)
Intel Corporation
[email protected]
(503) 712-4565
-----Original Message-----
From: Hu, Tan Chang [mailto:[email protected]]
Sent: Wednesday, July 22, 2015 8:27 AM
To: [email protected]
Cc: Naegle, John H
Subject: [E1000-devel] Intel Customer Support Service Request Management
request # 8001197134
Desr sir,
As per understanding from the last email from Intel support dated July 22,
2015, the ticket 8001197234 has been passed on to the Intel driver development
team. Please let us know if additional iformation, besides the previously
submitted, are needed to resolve this issue.
Thanks
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