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Bug
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Resolution: Won't Do
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Major
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None
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rhel-9.1.0
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None
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Moderate
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rhel-sst-virtualization-cloud
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ssg_virtualization
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3
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False
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None
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None
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None
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Automated
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If docs needed, set a value
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Unspecified
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None
+++ This bug was initially created as a clone of Bug #2128446 +++
Description of problem:
UDP data loss is supposed be less then 1% in the below situation.
1. vRSS hashing excludes the port where UDP data is through.
- ethtool -n eth0 rx-flow-hash udp4
UDP over IPV4 flows use these fields for computing Hash flow key:
IP SA
IP DA
2. Packets length is larger than MTU, e.g. 8k.
Tested with 2 Standard_D15_v2 VMs using the below commands on each respectively:
- iperf3 -s 4 -p 8001
- iperf3 -u -c 10.0.0.4 -p 8001 -4 -b 0 -l 8k -P 64 -t 60 --get-server-output -i 60
And the result is:
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-60.01 sec 1.09 MBytes 152 Kbits/sec 4.741 ms 31221/31360 (1e+02%) receiver
[ 6] 0.00-60.01 sec 944 KBytes 129 Kbits/sec 3.708 ms 30642/30760 (1e+02%) receiver
...
[SUM] 0.00-60.01 sec 55.2 MBytes 7.71 Mbits/sec 5.510 ms 1646217/1653281 (1e+02%) receiver
Version-Release number of selected component (if applicable):
5.14.0-162.el9.x86_64
How reproducible:
100% on Azure.
Steps to Reproduce:
1. Create 2 VMs and disable vRSS hashing by -
- ethtool -N eth0 rx-flow-hash udp4 sd
2. run iperf3 commands in description individually.
Actual results:
Data loss is greater than 1%.
Expected results:
Data loss is less than 1%.
Additional info:
1. This issue presents from 8.6 through 9.1.
2. Related BZ - https://bugzilla.redhat.com/show_bug.cgi?id=1474300 (looks like a re-occurrence).
3. Issue does not present when packets are smaller than MTU.
4. Issue presents on other VM sizes, e.g. Standard_D16s_v5.
- is blocked by
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RHEL-7216 [Azure][RHEL-8] UDP data loss is big at packets larger than MTU even without vRSS hashing
- Closed
- external trackers