osmocom-net-gprs June 2019

osmocom-net-gprs@lists.osmocom.org

1 participants
2 discussions

RFC: unit tests for kernel GTP module
by Harald Welte 31 Dec '25

31 Dec '25

Dear GTP-interested folks, I would love to somehow get towards some degree of unit testing (or even "continuous integration") for teh kernel GTP code. We currently have the original code in the kernel, we had some recent small fixes and now are getting more patches into place. With relatively few active users out there (and probably none of them in production yet), it's particularly easy to introduce regressions while working on the code. Also, having tested new code even against a test set with limited covrage could help to get more confidence in new patches and thus get them merged sooner. Using tools like sgsnemu of OpenGGSN and the command line tools included in libgtpnl, it should be possibel to cook up some scripts for testing. Even the most basic set of tests would be an improvement over what we have now. One could also think about pcap replay to test with hand-crafted or real-world packets from other GTP implementations. As much as I'd like to put something like this into place myself, I don't think I will be able to work much on this in the near future. The GTP module at this point is a pure hobby and contrary to some years ago while I started it, I don't have any contract work in the GTP area at this point, so other projects currently unfortunately get more attention. So in case somebody among the GTP-interested parties (Travelping, OAI, ...) would want to do something in terms of testing, I'd be more than happy if somebody would step ahead. Otherwise it's all just vapourware going to end up on my ever-growing TODO list :/ Also, if netdev folks have some ideas/pointers about possible frameworks/tools for this kind of testing [it must exist for at least some other kernel networking code?]: Please let me know. I'd be interested to have a look if there's something that can be used as a basis (starting network namespaces, sending/transmitting packets, test case startup/teardown, ...) My "old school" approach would have been to start one or multiple user-mode-linux kernels (those that are to be tested), and then have scripts that set up a gtp socket and gtp tunnels via the libgtp command line tools, and throw packets at that. But I'm sure there must be quite powerful frameworks for that kind of testing in the 21st century? How do other tunneling implementations handle this? Regards, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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high ksoftirqd while using module gtp?
by Tony Clark 19 Jun '19

19 Jun '19

Dear All, I've been using the GTP-U kernel module to communicate with a P-GW. Running Fedora 29, kernel 4.18.16-300.fc29.x86_64. At high traffic levels through the GTP-U tunnel I see the performance degrade as 100% CPU is consumed by a single ksoftirqd process. It is running on a multi-cpu machine and as far as I can tell the load is evenly spread across the cpus (ie either manually via smp_affinity, or even irqbalance, checking /proc/interrupts so forth.). Has anyone else experienced this? Is there any particular area you could recommend I investigate to find the root cause of this bottleneck, as i'm starting to scratch my head where to look next... Thanks in advance Tony ---- FYI modinfo gtp filename: /lib/modules/4.18.16-300.fc29.x86_64/kernel/drivers/net/gtp.ko.xz alias: net-pf-16-proto-16-family-gtp alias: rtnl-link-gtp description: Interface driver for GTP encapsulated traffic author: Harald Welte <hwelte(a)sysmocom.de> license: GPL depends: udp_tunnel retpoline: Y intree: Y name: gtp vermagic: 4.18.16-300.fc29.x86_64 SMP mod_unload modinfo udp_tunnel filename: /lib/modules/4.18.16-300.fc29.x86_64/kernel/net/ipv4/udp_tunnel.ko.xz license: GPL depends: retpoline: Y intree: Y name: udp_tunnel vermagic: 4.18.16-300.fc29.x86_64 SMP mod_unload

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osmocom-net-gprs June 2019