1iperf3 Development 2================== 3 4The iperf3 project is hosted on GitHub at: 5 6http://github.com/esnet/iperf 7 8This site includes the source code repository, issue tracker, and 9wiki. 10 11Mailing Lists 12------------- 13 14The developer list for iperf3 is: [email protected]. 15Information on joining the mailing list can be found at: 16 17http://groups.google.com/group/iperf-dev 18 19There is, at the moment, no mailing list for user questions, although 20a low volume of inquiries on the developer list is probably 21acceptable. If necessary, a user-oriented mailing list might be 22created in the future. 23 24Bug Reports 25----------- 26 27Before submitting a bug report, try checking out the latest version of 28the code, and confirm that it's not already fixed. Then submit to the 29iperf3 issue tracker on GitHub: 30 31https://github.com/esnet/iperf/issues 32 33**Note:** Issues submitted to the old iperf3 issue tracker on Google 34Code (or comments to existing issues on the Google Code issue tracker) 35will be ignored. 36 37Changes from iperf 2.x 38---------------------- 39 40New options (not necessarily complete, please refer to the manual page 41for a complete list of iperf3 options):: 42 43 -V, --verbose more detailed output than before 44 -J, --json output in JSON format 45 -Z, --zerocopy use a 'zero copy' sendfile() method of sending data 46 -O, --omit N omit the first n seconds (to ignore slowstart) 47 -T, --title str prefix every output line with this string 48 -F, --file name xmit/recv the specified file 49 -A, --affinity n/n,m set CPU affinity (Linux and FreeBSD only) 50 -k, --blockcount #[KMG] number of blocks (packets) to transmit (instead 51 of -t or -n) 52 -L, --flowlabel set IPv6 flow label (Linux only) 53 54Changed flags:: 55 56 -C, --linux-congestion set congestion control algorithm (Linux only) 57 (-Z in iperf2) 58 59 60Deprecated flags (currently no plans to support):: 61 62 -d, --dualtest Do a bidirectional test simultaneously 63 -r, --tradeoff Do a bidirectional test individually 64 -T, --ttl time-to-live, for multicast (default 1) 65 -x, --reportexclude [CDMSV] exclude C(connection) D(data) M(multicast) 66 S(settings) V(server) reports 67 -y, --reportstyle C report as a Comma-Separated Values 68 69Also deprecated is the ability to set the options via environment 70variables. 71 72Known Issues 73------------ 74 75The following problems are notable known issues, which are probably of 76interest to a large fraction of users or have high impact for some 77users, and for which issues have already been filed in the issue 78tracker. These issues are either open (indicating no solution 79currently exists) or closed with the notation that no further attempts 80to solve the problem are currently being made: 81 82* UDP performance: Some problems have been noticed with iperf3 on the 83 ESnet 100G testbed at high UDP rates (above 10Gbps). The symptom is 84 that on any particular run of iperf3 the receiver reports a loss 85 rate of about 20%, regardless of the ``-b`` option used on the client 86 side. This problem appears not to be iperf3-specific, and may be 87 due to the placement of the iperf3 process on a CPU and its relation 88 to the inbound NIC. In some cases this problem can be mitigated by 89 an appropriate use of the CPU affinity (``-A``) option. (Issue #55) 90 91* Interval reports on high-loss networks: The way iperf3 is currently 92 implemented, the sender write command will block until the entire 93 block has been written. This means that it might take several 94 seconds to send a full block if the network has high loss, and the 95 interval reports will have widely varying interval times. A 96 solution is being discussed, but in the meantime a work around is to 97 try using a small block size, for example ``-l 4K``. (Issue #125, 98 a fix will be released in iperf 3.1) 99 100* The ``-Z`` flag sometimes causes the iperf3 client to hang on OSX. 101 (Issue #129) 102 103* On OpenBSD, the server seems to require a ``-4`` argument, implying 104 that it can only be used with IPv4. (Issue #108) 105 106* When specifying the TCP buffer size using the ``-w`` flag on Linux, 107 the Linux kernel automatically doubles the value passed in to 108 compensate for overheads. (This can be observed by using 109 iperf3's ``--debug`` flag.) However, CWND does not actually ramp up 110 to the doubled value, but only to about 75% of the doubled 111 value. Some part of this behavior is documented in the tcp(7) 112 manual page. (Issue #145) 113 114* On some platforms (observed on at least one version of Ubuntu 115 Linux), it might be necessary to invoke ``ldconfig`` manually after 116 doing a ``make install`` before the ``iperf3`` executable can find 117 its shared library. (Issue #153) 118 119There are, of course, many other open and closed issues in the issue 120tracker. 121 122Versioning 123---------- 124 125iperf3 version numbers use (roughly) a `Semantic Versioning 126<http://semver.org/>`_ scheme, in which version numbers consist of 127three parts: *MAJOR.MINOR.PATCH* 128 129The developers increment the: 130 131* *MAJOR* version when making incompatible API changes, 132 133* *MINOR* version when adding functionality in a backwards-compatible manner, and 134 135* *PATCH* version when making backwards-compatible bug fixes. 136 137Release Engineering Checklist 138----------------------------- 139 1401. Update the ``README`` and ``RELEASE_NOTES`` files to be accurate. Make sure 141 that the "Known Issues" section of the ``README`` file is up to date. 142 1432. Compose a release announcement. Most of the release announcement 144 can be written before tagging. 145 1463. Starting from a clean source tree (be sure that ``git status`` emits 147 no output):: 148 149 vi src/version.h # update the strings IPERF_VERSION and IPERF_VERSION_DATE 150 vi configure.ac # update version parameter in AC_INIT 151 vi src/iperf3.1 # update manpage revision date if needed 152 vi src/libiperf.3 # update manpage revision date if needed 153 git commit -a 154 ./bootstrap.sh # regenerate configure script, etc. 155 git commit -a 156 git push 157 158 ./make_release tag # this creates a tag in the local repo that matches the version.h version 159 git push --tags # Push the new tag to the GitHub repo 160 ./make_release tar # create tarball and compute SHA256 hash 161 162 These steps should be done on a platform with a relatively recent 163 version of autotools / libtools. Examples are MacOS / MacPorts or 164 FreeBSD. The versions of these tools in CentOS 6 are somewhat 165 older and probably should be avoided. 166 1674. Stage the tarball (and a file containing the SHA256 hash) to the 168 download site. Currently this is located on ``stats.es.net``. 169 1705. From another host, test the link in the release announcement by 171 downloading a fresh copy of the file and verifying the SHA256 172 checksum. 173 1746. Also verify (with file(1)) that the tarball is actually a gzipped 175 tarball. 176 1777. For extra points, actually try downloading, compiling, and 178 smoke-testing the results of the tarball on all supported 179 platforms. 180 1818. Plug the SHA256 checksum into the release announcement. 182 1839. Send the release announcement (PGP-signed) to these addresses: 184 185 * [email protected] 186 187 * [email protected] 188 189 * [email protected] 190 191 * [email protected] 192 19310. Update the iperf3 Project News section of the documentation site 194 to announce the new release (see ``docs/news.rst`` in the source 195 tree) and deploy a new build of the documentation to GitHub 196 Pages. 197 198