From: Haiyang Zhang <haiya...@microsoft.com> Update Documentation/networking/netvsc.txt for UDP hash level setting and related info.
Signed-off-by: Haiyang Zhang <haiya...@microsoft.com> --- Documentation/networking/netvsc.txt | 22 +++++++++++++++++----- 1 files changed, 17 insertions(+), 5 deletions(-) diff --git a/Documentation/networking/netvsc.txt b/Documentation/networking/netvsc.txt index 4ddb4e4..fa8d863 100644 --- a/Documentation/networking/netvsc.txt +++ b/Documentation/networking/netvsc.txt @@ -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 -------------------------------- -- 1.7.1
