iperf3 Development ================== The iperf3 project is hosted on GitHub at: http://github.com/esnet/iperf This site includes the source code repository, issue tracker, and wiki. Mailing Lists ------------- The developer list for iperf3 is: iperf-dev@googlegroups.com. Information on joining the mailing list can be found at: http://groups.google.com/group/iperf-dev There is, at the moment, no mailing list for user questions, although a low volume of inquiries on the developer list is probably acceptable. If necessary, a user-oriented mailing list might be created in the future. Bug Reports ----------- Before submitting a bug report, try checking out the latest version of the code, and confirm that it's not already fixed. Then submit to the iperf3 issue tracker on GitHub: https://github.com/esnet/iperf/issues **Note:** Issues submitted to the old iperf3 issue tracker on Google Code (or comments to existing issues on the Google Code issue tracker) will be ignored. Changes from iperf 2.x ---------------------- New options (not necessarily complete, please refer to the manual page for a complete list of iperf3 options):: -V, --verbose more detailed output than before -J, --json output in JSON format -Z, --zerocopy use a 'zero copy' sendfile() method of sending data -O, --omit N omit the first n seconds (to ignore slowstart) -T, --title str prefix every output line with this string -F, --file name xmit/recv the specified file -A, --affinity n/n,m set CPU affinity (Linux and FreeBSD only) -k, --blockcount #[KMG] number of blocks (packets) to transmit (instead of -t or -n) -L, --flowlabel set IPv6 flow label (Linux only) Changed flags:: -C, --linux-congestion set congestion control algorithm (Linux only) (-Z in iperf2) Deprecated flags (currently no plans to support):: -d, --dualtest Do a bidirectional test simultaneously -r, --tradeoff Do a bidirectional test individually -T, --ttl time-to-live, for multicast (default 1) -x, --reportexclude [CDMSV] exclude C(connection) D(data) M(multicast) S(settings) V(server) reports -y, --reportstyle C report as a Comma-Separated Values Also deprecated is the ability to set the options via environment variables. Known Issues ------------ The following problems are notable known issues, which are probably of interest to a large fraction of users or have high impact for some users, and for which issues have already been filed in the issue tracker. These issues are either open (indicating no solution currently exists) or closed with the notation that no further attempts to solve the problem are currently being made: * UDP performance: Some problems have been noticed with iperf3 on the ESnet 100G testbed at high UDP rates (above 10Gbps). The symptom is that on any particular run of iperf3 the receiver reports a loss rate of about 20%, regardless of the ``-b`` option used on the client side. This problem appears not to be iperf3-specific, and may be due to the placement of the iperf3 process on a CPU and its relation to the inbound NIC. In some cases this problem can be mitigated by an appropriate use of the CPU affinity (``-A``) option. (Issue #55) * Interval reports on high-loss networks: The way iperf3 is currently implemented, the sender write command will block until the entire block has been written. This means that it might take several seconds to send a full block if the network has high loss, and the interval reports will have widely varying interval times. A solution is being discussed, but in the meantime a work around is to try using a small block size, for example ``-l 4K``. (Issue #125, a fix will be released in iperf 3.1) * The ``-Z`` flag sometimes causes the iperf3 client to hang on OSX. (Issue #129) * On OpenBSD, the server seems to require a ``-4`` argument, implying that it can only be used with IPv4. (Issue #108) * When specifying the TCP buffer size using the ``-w`` flag on Linux, the Linux kernel automatically doubles the value passed in to compensate for overheads. (This can be observed by using iperf3's ``--debug`` flag.) However, CWND does not actually ramp up to the doubled value, but only to about 75% of the doubled value. Some part of this behavior is documented in the tcp(7) manual page. (Issue #145) * On some platforms (observed on at least one version of Ubuntu Linux), it might be necessary to invoke ``ldconfig`` manually after doing a ``make install`` before the ``iperf3`` executable can find its shared library. (Issue #153) There are, of course, many other open and closed issues in the issue tracker. Versioning ---------- iperf3 version numbers use (roughly) a `Semantic Versioning `_ scheme, in which version numbers consist of three parts: *MAJOR.MINOR.PATCH* The developers increment the: * *MAJOR* version when making incompatible API changes, * *MINOR* version when adding functionality in a backwards-compatible manner, and * *PATCH* version when making backwards-compatible bug fixes. Release Engineering Checklist ----------------------------- 1. Update the ``README`` and ``RELEASE_NOTES`` files to be accurate. Make sure that the "Known Issues" section of the ``README`` file is up to date. 2. Compose a release announcement. Most of the release announcement can be written before tagging. 3. Starting from a clean source tree (be sure that ``git status`` emits no output):: vi src/version.h # update the strings IPERF_VERSION and IPERF_VERSION_DATE vi configure.ac # update version parameter in AC_INIT vi src/iperf3.1 # update manpage revision date if needed vi src/libiperf.3 # update manpage revision date if needed git commit -a ./bootstrap.sh # regenerate configure script, etc. git commit -a git push ./make_release tag # this creates a tag in the local repo that matches the version.h version git push --tags # Push the new tag to the GitHub repo ./make_release tar # create tarball and compute SHA256 hash These steps should be done on a platform with a relatively recent version of autotools / libtools. Examples are MacOS / MacPorts or FreeBSD. The versions of these tools in CentOS 6 are somewhat older and probably should be avoided. 4. Stage the tarball (and a file containing the SHA256 hash) to the download site. Currently this is located on ``downloads.es.net``. 5. From another host, test the link in the release announcement by downloading a fresh copy of the file and verifying the SHA256 checksum. 6. Also verify (with file(1)) that the tarball is actually a gzipped tarball. 7. For extra points, actually try downloading, compiling, and smoke-testing the results of the tarball on all supported platforms. 8. Plug the SHA256 checksum into the release announcement. 9. Send the release announcement (PGP-signed) to these addresses: * iperf-dev@googlegroups.com * iperf-users@lists.sourceforge.net * perfsonar-user@internet2.edu * perfsonar-dev@internet2.edu 10. Update the iperf3 Project News section of the documentation site to announce the new release (see ``docs/news.rst`` in the source tree) and deploy a new build of the documentation to GitHub Pages. Code Authors ------------ The main authors of iperf3 are (in alphabetical order): Jon Dugan, Seth Elliott, Bruce A. Mah, Jeff Poskanzer, Kaustubh Prabhu. Additional code contributions have come from (also in alphabetical order): Mark Ashley, Aaron Brown, Aeneas Jaißle, Susant Sahani, Brian Tierney. iperf3 contains some original code from iperf2. The authors of iperf2 are (in alphabetical order): Jon Dugan, John Estabrook, Jim Ferbuson, Andrew Gallatin, Mark Gates, Kevin Gibbs, Stephen Hemminger, Nathan Jones, Feng Qin, Gerrit Renker, Ajay Tirumala, Alex Warshavsky.