[PATCH net-next,4/4] hv_netvsc: Update netvsc Document for UDP hash level setting
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STALE3346d
From: Haiyang Zhang <hidden>
Date: 2017-08-21 21:57:30
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lkml
Subsystem:
documentation, networking [general], the rest · Maintainers:
Jonathan Corbet, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Haiyang Zhang <haiyangz@microsoft.com> Update Documentation/networking/netvsc.txt for UDP hash level setting and related info. Signed-off-by: Haiyang Zhang <haiyangz@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 --------------------------------
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