Intel Flow Director results in TCP Out of Order traffic
Issue
- Intel Flow Director results in TCP Out of Order traffic
- TCP throughput and performance can be seriously degraded as a side effect.
- FDir ATR (Application Targeted Receive) functionality of
ixgberesults in TCP OoO or OfOTCPOFOQueuecounters growing innetstat -s - How to avoid negative performance impact in multiprocessing environments on process migration demonstrated by research paper "Why Does Flow Director Cause Packet Reordering? " by Wenji Wu, Phil De Mar, Matt Crawford of Fermilab - http://arxiv.org/pdf/1106.0443.pdf
Environment
- Red Hat Enterprise Linux
- Intel 82598, 82599, X520, X540, X550, X700 series or other network interface card using
ixgbeori40edriver - Intel Flow Director in ATR (Application Targeted Receive) mode
- TCP traffic
TCPOFOQueuestatistic in/proc/net/netstatshows large number- Unpinned processes migrating between CPU cores due to regular CPU scheduling
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