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authorHaiyang Zhang <haiyangz@microsoft.com>2017-08-21 19:22:40 -0700
committerDavid S. Miller <davem@davemloft.net>2017-08-22 14:08:12 -0700
commit3b0c34580b7ab9bb1d4a375e427af6a75ca45821 (patch)
treeedaaeedb401570d404c71ec1117a6e4bb85f5160 /Documentation/networking
parent4823eb2f3af44e2b9f7f02bed5a211e9ce79051f (diff)
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: Haiyang Zhang <haiyangz@microsoft.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/netvsc.txt22
1 files changed, 17 insertions, 5 deletions
diff --git a/Documentation/networking/netvsc.txt b/Documentation/networking/netvsc.txt
index 4ddb4e4b0426..fa8d86356791 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
--------------------------------