Here's the third published video of my FOSDEM talks, about the Varlink IPC system:

https://video.fosdem.org/2026/ub2147/NFNKEK-varlink-ipc-system-keynote.av1.webm

This was the last one of the three. Enjoy!

#systemd #fosdem #fosdem2026

@pid_eins should have counted the context switches of a portal call for maximum effect :p
@swick i am curious, for some simple portal how many context switches would you guess? (For a single portal gated request, ideally non-interactive if there is such a thing)

@pid_eins

best case: 6 context switches [request: app -> dbus-proxy -> broker -> portal frontend] -> [response: broker -> dbus-proxy -> app]

but with auth required on every connection: 8 context switches [request: app -> dbus-proxy -> broker -> portal frontend -> [credentials: broker -> portal frontend]] -> [response: broker -> dbus-proxy -> app]

and with a backend call: 12 context switches [request: app -> dbus-proxy -> broker -> portal frontend -> [credentials: broker -> portal frontend] -> broker -> portal backend] -> [response: broker -> portal frontend -> broker -> dbus-proxy -> app]

@swick @pid_eins you should multiply that by two, since you're switching into and out of kernel mode on every turn. Also GDBus that underlies this all does a bunch of thread hopping internally, so there's more switches still.