User events — but not quite yet

Posted Apr 19, 2022 4:08 UTC (Tue) by alison (subscriber, #63752)
In reply to: User events — but not quite yet by pbonzini
Parent article: User events — but not quite yet

Why is the new mechanism better than uprobes, which have easy-to-use BPF support via the USDT facility in the folly library:

https://github.com/facebook/folly/tree/main/folly/tracing

Compiling against all of folly to get the userspace tracing would be a pain, but the code is Apache-licensed, so perhaps that is not necessary.

User events — but not quite yet

Posted Apr 20, 2022 6:27 UTC (Wed) by lathiat (subscriber, #18567) [Link]

Note that USDT probes can also be defined using headers from systemtap (sys/sdt.h - systemtap-sdt-dev{el,}) but it doesn't actually require systemtap to use it's just where the headers live.

This library generally is GPLv2-only licensed but the relevant sys/sdt.h file is "dedicated to the public domain, pursuant to CC0 (https://creativecommons.org/publicdomain/zero/1.0/)"

It uses the same definitions and is source-compatible with the definitions from DTRACE (so the macros are named DTRACE_*):
https://sourceware.org/systemtap/wiki/AddingUserSpaceProb...
https://sourceware.org/systemtap/wiki/UserSpaceProbeImple...