[dpdk-dev] [Bug 399] ixgbe X540 PMD RSS is zero for NFSv3 NULL reply

bugzilla at dpdk.org bugzilla at dpdk.org
Thu Feb 13 23:34:42 CET 2020


https://bugs.dpdk.org/show_bug.cgi?id=399

            Bug ID: 399
           Summary: ixgbe X540 PMD RSS is zero for NFSv3 NULL reply
           Product: DPDK
           Version: 18.11
          Hardware: x86
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: ethdev
          Assignee: dev at dpdk.org
          Reporter: daveb at infinite.io
  Target Milestone: ---

Created attachment 84
  --> https://bugs.dpdk.org/attachment.cgi?id=84&action=edit
tcpdump -i eth3 -w /tmp/client80.mount.pcap host 10.240.160.1

We see packets with rte_mbuf.hash.rss == 0 for NFSv3 NULL reply packets, and
NFSv3 NFSACL reply packets, but all other packets appear correct.

Attached is a pcap, which when replayed through DPDK 18.11.3 having a copper
X540-based 10GbE NIC should show the zero RSS hashes for a restricted set of
packets.  It is okay on others, but an NFSv3 mount command will have its frames
directed to the wrong core due to rte_mbuf.hash.rss == 0.

This problem does NOT exhibit with the 82599 ixgbe PMD.

If you open this pcap with wireshark, this filter expression will limit your
view to only those packets that get a zero RSS hash.  All other packets in this
pcap had correct RSS values in rte_mbuf.hash.rss.

      rpc.procedure == 0 and rpc.msgtyp == 1 and (tcp.port == 2049)

This will select packets: 20, 44, 71, 91, 118, 138, 165, 185, 211, 230, 256,
275, 301, 320, 346, 365, 391, 410, 436, 455.  Each of these packets had
rte_mbuf.hash.rss == 0.  All other packets had valid hash.rss values.

The attached pcap holds the traffic as seen by the client, generated by this
command:

seq 10 | while read a; do sudo time mount -t nfs -o vers=3 10.240.160.1:/jot
/mnt/daveb; sudo umount /mnt/daveb; done

Our application is a bump-on-the-wire between client and server.  All packets
flow through our box (and DPDK 18.11.3) both directions.  The only packets with
a bad RSS are those indicated above.  The NIC in our box is (from kern.log):

Feb  7 16:43:06 firefly kernel: PE310G4BPi40T found, firmware version: 0xac

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