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Commit 3b0c3458 authored by Haiyang Zhang's avatar Haiyang Zhang Committed by David S. Miller
Browse files

hv_netvsc: Update netvsc Document for UDP hash level setting 



Update Documentation/networking/netvsc.txt for UDP hash level setting
and related info.

Signed-off-by: default avatarHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4823eb2f

Documentation/networking/netvsc.txt

+17 −5
Original line number Diff line number Diff line
@@ -21,11 +21,23 @@ Features 
  --------------------

  Hyper-V supports receive side scaling. For TCP, packets are

  distributed among available queues based on IP address and port

  number. Current versions of Hyper-V host, only distribute UDP

  packets based on the IP source and destination address.

  The port number is not used as part of the hash value for UDP.

  Fragmented IP packets are not distributed between queues;

  all fragmented packets arrive on the first channel.

  number.



  For UDP, we can switch UDP hash level between L3 and L4 by ethtool

  command. UDP over IPv4 and v6 can be set differently. The default

  hash level is L4. We currently only allow switching TX hash level

  from within the guests.



  On Azure, fragmented UDP packets have high loss rate with L4

  hashing. Using L3 hashing is recommended in this case.



  For example, for UDP over IPv4 on eth0:

  To include UDP port numbers in hasing:

        ethtool -N eth0 rx-flow-hash udp4 sdfn

  To exclude UDP port numbers in hasing:

        ethtool -N eth0 rx-flow-hash udp4 sd

  To show UDP hash level:

        ethtool -n eth0 rx-flow-hash udp4



  Generic Receive Offload, aka GRO

  --------------------------------