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version 1.1.1.1, 2021/03/17 00:36:45 version 1.1.1.2, 2023/09/27 11:14:54
Line 13  What is the history of iperf3, and what is the differe Line 13  What is the history of iperf3, and what is the differe
   threaded, and not worry about backwards compatibility with    threaded, and not worry about backwards compatibility with
   iperf2. Many of the feature requests for iperf3 came from the    iperf2. Many of the feature requests for iperf3 came from the
   perfSONAR project (http://www.perfsonar.net).    perfSONAR project (http://www.perfsonar.net).
 
   Then in 2014, Bob (Robert) McMahon from Broadcom restarted    Then in 2014, Bob (Robert) McMahon from Broadcom restarted
   development of iperf2 (See    development of iperf2 (See
   https://sourceforge.net/projects/iperf2/). He fixed many of the    https://sourceforge.net/projects/iperf2/). He fixed many of the
   problems with iperf2, and added a number of new features similar to    problems with iperf2, and added a number of new features similar to
  iperf3. iperf2.0.8, released in 2015, made iperf2 a useful tool. iperf2's   iperf3. iperf2.0.8, released in 2015, made iperf2 a useful tool. iperf2's
   current development is focused is on using UDP for latency testing, as well    current development is focused is on using UDP for latency testing, as well
   as broad platform support.    as broad platform support.
 
   As of this writing (2017), both iperf2 and iperf3 are being actively    As of this writing (2017), both iperf2 and iperf3 are being actively
   (although independently) developed.  We recommend being familiar with    (although independently) developed.  We recommend being familiar with
   both tools, and use whichever tool’s features best match your needs.    both tools, and use whichever tool’s features best match your needs.
 
   A feature comparison of iperf2, iperf3, and nuttcp is available at:    A feature comparison of iperf2, iperf3, and nuttcp is available at:
   https://fasterdata.es.net/performance-testing/network-troubleshooting-tools/throughput-tool-comparision/    https://fasterdata.es.net/performance-testing/network-troubleshooting-tools/throughput-tool-comparision/
 
 iperf3 parallel stream performance is much less than iperf2. Why?  iperf3 parallel stream performance is much less than iperf2. Why?
   iperf3 is single threaded, and iperf2 is multi-threaded. We    iperf3 is single threaded, and iperf2 is multi-threaded. We
   recommend using iperf2 for parallel streams.    recommend using iperf2 for parallel streams.
   If you want to use multiple iperf3 streams use the method described `here <https://fasterdata.es.net/performance-testing/network-troubleshooting-tools/iperf/multi-stream-iperf3/>`_.    If you want to use multiple iperf3 streams use the method described `here <https://fasterdata.es.net/performance-testing/network-troubleshooting-tools/iperf/multi-stream-iperf3/>`_.
 
 I’m trying to use iperf3 on Windows, but having trouble. What should I do?  I’m trying to use iperf3 on Windows, but having trouble. What should I do?
   iperf3 is not officially supported on Windows, but iperf2 is. We    iperf3 is not officially supported on Windows, but iperf2 is. We
   recommend you use iperf2.    recommend you use iperf2.
Line 41  I’m trying to use iperf3 on Windows, but having trou Line 41  I’m trying to use iperf3 on Windows, but having trou
   Some people are using Cygwin to run iperf3 in Windows, but not all    Some people are using Cygwin to run iperf3 in Windows, but not all
   options will work.  Some community-provided binaries of iperf3 for    options will work.  Some community-provided binaries of iperf3 for
   Windows exist.    Windows exist.
 
 How can I build a statically-linked executable of iperf3?  How can I build a statically-linked executable of iperf3?
   There are a number of reasons for building an iperf3 executable with    There are a number of reasons for building an iperf3 executable with
   no dependencies on any shared libraries.  Unfortunately this isn't    no dependencies on any shared libraries.  Unfortunately this isn't
Line 116  How can I build on a system that doesn't support profi Line 116  How can I build on a system that doesn't support profi
   
      And then run ``./bootstrap.sh``, that will regenerate the project       And then run ``./bootstrap.sh``, that will regenerate the project
      Makefiles to make the exclusion of the profiled iperf3 executable       Makefiles to make the exclusion of the profiled iperf3 executable
     permanant (within that source tree).     permanent (within that source tree).
   
 I'm seeing quite a bit of unexpected UDP loss. Why?  I'm seeing quite a bit of unexpected UDP loss. Why?
   First, confirm you are using iperf 3.1.5 or higher. There was an    First, confirm you are using iperf 3.1.5 or higher. There was an
   issue with the default UDP send size that was fixed in    issue with the default UDP send size that was fixed in
   3.1.5. Second, try adding the flag ``-w2M`` to increase the socket    3.1.5. Second, try adding the flag ``-w2M`` to increase the socket
   buffer sizes. That seems to make a big difference on some hosts.    buffer sizes. That seems to make a big difference on some hosts.
 
 iperf3 UDP does not seem to work at bandwidths less than 100Kbps. Why?  iperf3 UDP does not seem to work at bandwidths less than 100Kbps. Why?
   You'll need to reduce the default packet length to get UDP rates of less that 100Kbps. Try ``-l100``.    You'll need to reduce the default packet length to get UDP rates of less that 100Kbps. Try ``-l100``.
 
 TCP throughput drops to (almost) zero during a test, what's going on?  TCP throughput drops to (almost) zero during a test, what's going on?
   A drop in throughput to almost zero, except maybe for the first    A drop in throughput to almost zero, except maybe for the first
   reported interval(s), may be related to problems in NIC TCP Offload,    reported interval(s), may be related to problems in NIC TCP Offload,
Line 184  What congestion control algorithms are supported? Line 184  What congestion control algorithms are supported?
   On Linux, run this command to see the available congestion control    On Linux, run this command to see the available congestion control
   algorithms (note that some algorithms are packaged as kernel    algorithms (note that some algorithms are packaged as kernel
   modules, which must be loaded before they can be used)::    modules, which must be loaded before they can be used)::
    
     /sbin/sysctl net.ipv4.tcp_available_congestion_control      /sbin/sysctl net.ipv4.tcp_available_congestion_control
   
   On FreeBSD, the equivalent command is::    On FreeBSD, the equivalent command is::
   
     /sbin/sysctl net.inet.tcp.cc.available      /sbin/sysctl net.inet.tcp.cc.available
 
 I’m using the ``--logfile`` option. How do I see file output in real time?  I’m using the ``--logfile`` option. How do I see file output in real time?
   Use the ``--forceflush`` flag.    Use the ``--forceflush`` flag.
   
Line 252  I have a question regarding iperf3...what's the best w Line 252  I have a question regarding iperf3...what's the best w
   We discourage the use of the iperf3 issue tracker on GitHub for    We discourage the use of the iperf3 issue tracker on GitHub for
   support questions.  Actual bug reports, enhancement requests, or    support questions.  Actual bug reports, enhancement requests, or
   pull requests are encouraged, however.    pull requests are encouraged, however.
   
   
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