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Iperf3.9 packet count for burst mode seems broken when sending UDP traffic #1192

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funglee2k opened this issue Aug 21, 2021 · 3 comments
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Iperf3.9 packet count for burst mode seems broken when sending UDP traffic #1192

funglee2k opened this issue Aug 21, 2021 · 3 comments

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@funglee2k
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NOTE: The iperf3 issue tracker is for registering bugs, enhancement
requests, or submissions of code. It is not a means for asking
questions about building or using iperf3. Those are best directed
towards the iperf3 mailing list at [email protected] or
question sites such as Stack Overflow
(http://www.stackoverflow.com/). A list of frequently-asked questions
regarding iperf3 can be found at http://software.es.net/iperf/faq.html.

Context

For some reason, iperf3 -b packet count for burst mode seems broken. Iperf3 actually sends as fast as possible when I use the "packet count for burst mode".

  • Version of iperf3:
    iperf 3.9 (cJSON 1.7.13)
    Linux ip-172-31-33-18 5.4.0-1048-aws ability to run iperf on a single port #50-Ubuntu SMP Mon May 3 21:44:17 UTC 2021 x86_64
    Optional features available: CPU affinity setting, IPv6 flow label, SCTP, TCP congestion algorithm setting, sendfile / zerocopy, socket pacing, authentication

Two files installed: https://iperf.fr/iperf-download.php#more-recent
ubuntu@ip-172-31-33-18:$ md5sum iperf3_3.9-1_amd64.deb
0b50b6f6a64b61c967f31304c2fffdb7 iperf3_3.9-1_amd64.deb
ubuntu@ip-172-31-33-18:$ md5sum libiperf0_3.9-1_amd64.deb
3334f380a401bf23517fadec6238bb7e libiperf0_3.9-1_amd64.deb

  • Hardware:
    AWS EC2 instances

  • Operating system (and distribution, if any):
    Ubuntu 20.04 LTS
    ubuntu@ip-172-31-33-18:~$ uname -a
    Linux ip-172-31-33-18 5.4.0-1048-aws ability to run iperf on a single port #50-Ubuntu SMP Mon May 3 21:44:17 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Please note: iperf3 is supported on Linux, FreeBSD, and macOS.
Support may be provided on a best-effort basis to other UNIX-like
platforms. We cannot provide support for building and/or running
iperf3 on Windows, iOS, or Android.

Please fill out one of the "Bug Report" or "Enhancement Request"
sections, as appropriate.

Bug Report

  • Expected Behavior
    When using -b 10M/100, we expect to see iperf3 sending at 10Mbps with a burst of 100 packets.

  • Actual Behavior
    Iperf3 sending as fast as possible, for example

ubuntu@ip-172-31-33-18:~$ iperf3 -c localhost -4 -u -t 5 -l 1360 -R -b 10M/100 --get-server-output
Connecting to host localhost, port 5201
Reverse mode, remote host localhost is sending
[ 5] local 127.0.0.1 port 41672 connected to 127.0.0.1 port 5201
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-1.00 sec 240 MBytes 2.02 Gbits/sec 0.002 ms 0/185276 (0%)
[ 5] 1.00-2.00 sec 280 MBytes 2.35 Gbits/sec 0.002 ms 0/215599 (0%)
[ 5] 2.00-3.00 sec 266 MBytes 2.23 Gbits/sec 0.002 ms 0/205015 (0%)
[ 5] 3.00-4.00 sec 274 MBytes 2.29 Gbits/sec 0.002 ms 0/210911 (0%)
[ 5] 4.00-5.00 sec 280 MBytes 2.35 Gbits/sec 0.003 ms 0/216159 (0%)

[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-5.00 sec 1.31 GBytes 2.25 Gbits/sec 0.000 ms 0/1033000 (0%) sender
[ 5] 0.00-5.00 sec 1.31 GBytes 2.25 Gbits/sec 0.003 ms 0/1032960 (0%) receiver

Server output:

Server listening on 5201

Accepted connection from 127.0.0.1, port 60380
[ 5] local 127.0.0.1 port 5201 connected to 127.0.0.1 port 41672
[ ID] Interval Transfer Bitrate Total Datagrams
[ 5] 0.00-1.00 sec 240 MBytes 2.02 Gbits/sec 185400
[ 5] 1.00-2.00 sec 280 MBytes 2.35 Gbits/sec 215600
[ 5] 2.00-3.00 sec 266 MBytes 2.23 Gbits/sec 205000
[ 5] 3.00-4.00 sec 274 MBytes 2.29 Gbits/sec 210900
[ 5] 4.00-5.00 sec 280 MBytes 2.35 Gbits/sec 216100

[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-5.00 sec 1.31 GBytes 2.25 Gbits/sec 0.000 ms 0/1033000 (0%) sender

iperf Done.

  • Steps to Reproduce
    ** Installation 3.9
    sudo dpkg -i libiperf0_3.9-1_amd64.deb iperf3_3.9-1_amd64.deb
    Selecting previously unselected package libiperf0:amd64.
    (Reading database ... 93789 files and directories currently installed.)
    Preparing to unpack libiperf0_3.9-1_amd64.deb ...
    Unpacking libiperf0:amd64 (3.9-1) ...
    Selecting previously unselected package iperf3.
    Preparing to unpack iperf3_3.9-1_amd64.deb ...
    Unpacking iperf3 (3.9-1) ...
    Setting up libiperf0:amd64 (3.9-1) ...
    Setting up iperf3 (3.9-1) ...
    Processing triggers for libc-bin (2.31-0ubuntu9.2) ...
    Processing triggers for man-db (2.9.1-1) ...
    ubuntu@ip-172-31-33-18:$ iperf3 -v
    iperf 3.9 (cJSON 1.7.13)
    Linux ip-172-31-33-18 5.4.0-1048-aws ability to run iperf on a single port #50-Ubuntu SMP Mon May 3 21:44:17 UTC 2021 x86_64
    Optional features available: CPU affinity setting, IPv6 flow label, SCTP, TCP congestion algorithm setting, sendfile / zerocopy, socket pacing, authentication
    ** start server
    ubuntu@ip-172-31-33-18:    $ iperf3 -s -D
    ** Without the burst mode, everything looks normal. (The following is a working case without burst mode.
    ubuntu@ip-172-31-33-18:~$ iperf3 -c localhost -4 -u -t 5 -l 1360 -R -b 10M
    Connecting to host localhost, port 5201
    Reverse mode, remote host localhost is sending
    [ 5] local 127.0.0.1 port 41108 connected to 127.0.0.1 port 5201
    [ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
    [ 5] 0.00-1.00 sec 1.19 MBytes 10.0 Mbits/sec 0.022 ms 0/919 (0%)
    [ 5] 1.00-2.00 sec 1.19 MBytes 10.0 Mbits/sec 0.027 ms 0/919 (0%)
    [ 5] 2.00-3.00 sec 1.19 MBytes 10.0 Mbits/sec 0.070 ms 0/919 (0%)
    [ 5] 3.00-4.00 sec 1.19 MBytes 10.0 Mbits/sec 0.074 ms 0/919 (0%)
    [ 5] 4.00-5.00 sec 1.19 MBytes 10.0 Mbits/sec 0.025 ms 0/919 (0%)

[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-5.00 sec 5.96 MBytes 10.0 Mbits/sec 0.000 ms 0/4596 (0%) sender
[ 5] 0.00-5.00 sec 5.96 MBytes 10.0 Mbits/sec 0.025 ms 0/4595 (0%) receiver

iperf Done.

**With burst mode "-b 10M/10", it seems server sending really fast.

ubuntu@ip-172-31-33-18:~$ iperf3 -c localhost -4 -u -t 5 -l 1360 -R -b 10M/10
Connecting to host localhost, port 5201
Reverse mode, remote host localhost is sending
[ 5] local 127.0.0.1 port 42043 connected to 127.0.0.1 port 5201
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-1.00 sec 201 MBytes 1.69 Gbits/sec 0.003 ms 0/155274 (0%)
[ 5] 1.00-2.00 sec 235 MBytes 1.97 Gbits/sec 0.003 ms 0/181217 (0%)
[ 5] 2.00-3.00 sec 232 MBytes 1.95 Gbits/sec 0.016 ms 38/178878 (0.021%)
[ 5] 3.00-4.00 sec 232 MBytes 1.95 Gbits/sec 0.003 ms 0/178992 (0%)
[ 5] 4.00-5.00 sec 236 MBytes 1.98 Gbits/sec 0.003 ms 0/181583 (0%)

[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-5.00 sec 1.11 GBytes 1.91 Gbits/sec 0.000 ms 0/875960 (0%) sender
[ 5] 0.00-5.00 sec 1.11 GBytes 1.91 Gbits/sec 0.003 ms 38/875944 (0.0043%) receiver

iperf Done.

**With burst mode, -b 1M/10, iperf3 could not send at 1Mbps but 2.0Gbps

ubuntu@ip-172-31-33-18:~$ iperf3 -c localhost -4 -u -t 5 -l 1360 -R -b 1M/10 --get-server-output
Connecting to host localhost, port 5201
Reverse mode, remote host localhost is sending
[ 5] local 127.0.0.1 port 46677 connected to 127.0.0.1 port 5201
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-1.00 sec 211 MBytes 1.77 Gbits/sec 0.041 ms 0/163023 (0%)
[ 5] 1.00-2.00 sec 237 MBytes 1.99 Gbits/sec 0.004 ms 0/183098 (0%)
[ 5] 2.00-3.00 sec 242 MBytes 2.03 Gbits/sec 0.003 ms 0/186494 (0%)
[ 5] 3.00-4.00 sec 252 MBytes 2.11 Gbits/sec 0.003 ms 0/194086 (0%)
[ 5] 4.00-5.00 sec 227 MBytes 1.90 Gbits/sec 0.018 ms 454/175425 (0.26%)

[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-5.00 sec 1.14 GBytes 1.96 Gbits/sec 0.000 ms 0/902140 (0%) sender
[ 5] 0.00-5.00 sec 1.14 GBytes 1.96 Gbits/sec 0.018 ms 454/902126 (0.05%) receiver

Server output:
Accepted connection from 127.0.0.1, port 60376
[ 5] local 127.0.0.1 port 5201 connected to 127.0.0.1 port 46677
[ ID] Interval Transfer Bitrate Total Datagrams
[ 5] 0.00-1.00 sec 211 MBytes 1.77 Gbits/sec 163040
[ 5] 1.00-2.00 sec 237 MBytes 1.99 Gbits/sec 183090
[ 5] 2.00-3.00 sec 242 MBytes 2.03 Gbits/sec 186500
[ 5] 3.00-4.00 sec 252 MBytes 2.11 Gbits/sec 194080
[ 5] 4.00-5.00 sec 228 MBytes 1.91 Gbits/sec 175430

[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-5.00 sec 1.14 GBytes 1.96 Gbits/sec 0.000 ms 0/902140 (0%) sender

iperf Done.

  • Possible Solution

Don't know.
Please submit patches or code changes as a pull request.

Enhancement Request

  • Current behavior

  • Desired behavior

  • Implementation notes

If submitting a proposed implementation of an enhancement request,
please use the pull request mechanism.
@funglee2k
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iperf3.9-likely-bug.txt
iperf3.10.1-no-issue.txt

I checked out src code, and it seems that I can reproduce the bug with 3.9.

@davidBar-On
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I believe this issue was fixed by PR #1090 in iperf3.10.

@funglee2k
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funglee2k commented Aug 21, 2021 •
edited
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I believe this issue was fixed by PR #1090 in iperf3.10.

thanks David.

Please mark it duplicated and close it.

@fitchtravis fitchtravis mentioned this issue Jan 14, 2025
Closed
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