Am 06.08.25 um 05:46 schrieb Jon Chiappetta via Openvpn-devel:
Hi,
This is my first time posting to a mailing list. I worked on a possible
performance proof-of-concept modification to the OpenVPN source code.
The code is in rough shape as I just wrote it this long weekend but I
wanted to see if anyone had any interesting feedback for such work.
Blog Post: https://fossjon.com/2025/08/05/modifying-openvpn-source-code-
to-allow-for-bulk-reads-max-mtu-and-jumbo-tcp-for-highly-improved-
performance/ <https://fossjon.com/2025/08/05/modifying-openvpn-source-
code-to-allow-for-bulk-reads-max-mtu-and-jumbo-tcp-for-highly-improved-
performance/>
> Max MTU which now matches the rest of your network clients (1500 bytes)
I have no idea what this means. OpenVPN always supported different MTU
sizes and MTU 1500 is standard.
> Bulk reads from the tun interface (6 reads)
> TCP connection protocol only (single jumbo write transfers)
> Performance improvements now allows for (6 reads x 1500 bytes == 9000
bytes)
So basically, from your explanation the main thing is to try to
write/read multiple packets in one batch on the TCP socket instead of
just reading/writing a single packet. I can see that this improves
performance.
Do you have any idea how much this actually improves performance? Your
blog post shows a speedtest with 500 MBit/s but that is not actually
saying much. In my own test setup, the current OpenVPN is capable over a
Gigabit, a before/after from your test setup would nice to see.
POC Diff: https://github.com/stoops/openvpn/compare/main <https://
github.com/stoops/openvpn/compare/main>…mods
Might be good enough for a POC but from quick glance it looks like there
needs to cleanup make this an actual commit.
If this is the wrong place I apologize in advance,
Thanks for your time,
No, this is the right place.
Arne
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