The iperf3 project is hosted on GitHub at:
This site includes the source code repository, issue tracker, and wiki.
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.
Before submitting a bug report, try checking out the latest version of the code, and confirm that it’s not already fixed. Also see the iperf3 FAQ. Then submit to the iperf3 issue tracker on GitHub:
https://github.com/esnet/iperf/issues
For reporting potential security issues, please contact the developers at iperf@es.net.
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.
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.
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:
The -Z flag sometimes causes the iperf3 client to hang on OSX.
(Issue #129)
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.
Although the -w flag is documented as setting the (TCP) window
size, it is also used to set the socket buffer size. This has been
shown to be helpful with high-bitrate UDP tests.
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)
The results printed on the server side at the end of a test do not correctly reflect the client-side measurements. This is due to the ordering of computing and transferring results between the client and server. (Issue #293)
The server could have a very short measurement reporting interval at the end of a test (particularly a UDP test), containing few or no packets. This issue is due to an artifact of timing between the client and server. (Issue #278)
There are, of course, many other open and closed issues in the issue tracker.
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.
Start from a clean source tree (be sure that git status emits
no output). Also ensure up-to-date installs of autoconf and
automake.
Ensure that README.md and LICENSE have correct copyright
dates.
Update the README.md and RELNOTES.md files to be accurate. Make sure
that the “Known Issues” section of the README.md file and in this document
are up to date.
Compose a release announcement. Most of the release announcement can be written before tagging. Usually the previous version’s announcement can be used as a starting point.
Make the changes necessary to produce the new version, such as bumping version numbers:
vi RELNOTES.md # update version number and release date
vi configure.ac # update version parameter in AC_INIT
# (there should not be any "+" in artifacts)
vi src/iperf3.1 # update manpage revision date (only if needed)
vi src/libiperf.3 # update manpage revision date (only if needed)
git commit -a # commit changes to the local repository only
# (commit log should mention version number)
./bootstrap.sh # regenerate configure script, etc.
git commit -a # commit changes to the local repository only
# (commit can be simply "Regen.")
# Assuming that $VERSION is the version number to be released...
./make_release tag $VERSION # this creates a tag in the local repo
./make_release tar $VERSION # 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 and similar distributions are somewhat older and probably should be avoided.
The result will be release artifacts that should be used for
pre-testing. One will be a compressed tarball
(e.g. iperf-3.17.1.tar.gz) and the other will contain SHA256
checksum (e.g. iperf-3.17.1.tar.gz.sha256)
Stage the tarball (and a file containing the SHA256 hash) to the
download site. Currently this is located on downloads.es.net
in the directory /var/www/html/pub/iperf/.
From another host, test the link in the release announcement by downloading a fresh copy of the file and verifying the SHA256 checksum. Checking all other links in the release announcement is strongly recommended as well.
The link to the tarball will be something of the form
https://downloads.es.net/pub/iperf/iperf-3.17.1.tar.gz. If
composing a release announcement using a HTML-aware editor, verify
the link targets point to the correct artifacts.
Also verify (with file(1)) that the tarball is actually a gzipped tarball.
Try downloading, compiling, and smoke-testing the results of the tarball on all supported platforms.
Verify that the version string in iperf3 --version matches the
version number of the artifacts.
Plug the SHA256 checksum into the release announcement.
(optional) PGP-sign the release announcement text using gpg
--clearsign. The signed announcement will be sent out in a
subsequent emails, but could also be archived. Decoupling the
signing from emailing allows a signed release announcement to be
resent via email or sent by other, non-email means.
At this point, the release can and should be considered finalized. To commit the release-engineering-related changes to GitHub and make them public, push them out thusly:
git push # Push version changes
git push --tags # Push the new tag to the GitHub repo
Update GitHub Releases with the current release notes. Start from:
https://github.com/esnet/iperf/releases/new. Remember to
properly select the tag from the dropdown menu and drop
the artifacts into the GitHub Release. Check “Set as the latest
release” and (optionally) “Create a discussion for this release”.
Send the release announcement to the following addresses. Remember to turn off signing in the MUA, if applicable. Remember to check the source address when posting to lists, as “closed” list will reject posting from all from registered email addresses.
Note: Thunderbird sometimes mangles the PGP-signed release announcement so that it does not verify correctly. This could be due to Thunderbird trying to wrap the length of extremely long lines (such as the SHA256 hash). Apple Mail and mutt seem to handle this situation correctly. Testing the release announcement sending process by sending a copy to oneself first and attempting to verify the signature is highly encouraged.
Announce the new release in the #iperf3 channel in ESnet Slack.
Update the iperf3 Project News section of the documentation site
to announce the new release (see docs/news.rst and
docs/conf.py in the source tree) and deploy a new build of the
documentation to GitHub Pages. Be sure to double-check version
numbers and copyright dates.
If an update to the on-line manual page is needed, it can be
generated with this sequence of commands (tested on CentOS 7) and
import the result into invoking.rst:
TERM=
export TERM
nroff -Tascii -c -man src/iperf3.1 | ul | sed 's/^/ /' > iperf3.txt
Update the version number in configure.ac to some
post-release number (with a “+”) and regenerate:
vi configure.ac # update version in AC_INIT, add "+"
git commit configure.ac # commit changes to local repository
# commit log should mention
# "post-release version bump"
./bootstrap.sh # regenerate configure script, etc.
git commit -a # commit changes to local repository
# (commit can be simply "Regen.")
# test
git push