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# eu-stacktrace development branch
eu-stacktrace is (will be) a utility to process a stream of raw stack
samples (such as those obtained from the Linux kernel's
PERF_SAMPLE_STACK facility) into a stream of stack traces (such as
those obtained from PERF_SAMPLE_CALLCHAIN), freeing various profiling
utilities from having to implement their own backtracing logic.
For the time being, eu-stacktrace is meant to be fed data from a
profiling tool via a pipe or fifo. We will see how well this idea
works as implementation proceeds.
The goal is to work with various profiler data formats. For the
prototype, Serhei is working to support sysprof's data format. We'd
like to adapt sysprof to distros compiled with omit-framepointer,
which will require sysprof to consume PERF_SAMPLE_STACK data. After
that, supporting perf's native data format is an obvious prerequisite
for merging this branch into elfutils. Ideally, we would like for
eu-stacktrace to also convert between different profile data formats
(e.g. taking sysprof data as input and emitting perf data, and
vice-versa), but this may be out-of-scope given the amount of code
that would need to be written to handle profile data other than stack
traces.
Link to latest roadmap and discussion thread:
- 2023/05 https://sourceware.org/pipermail/elfutils-devel/2023q2/006151.html
## build & run (for now)
Requirements:
- /usr/include/sysprof-4 headers (e.g. `sysprof-devel` package on Fedora)
- `sysprof` polkit actions installed systemwide (e.g. `sysprof` package on Fedora)
- sysprof with the serhei/samples-via-fifo patchset [1]
- some detailed notes on how I compiled sysprof via jhbuild here [2];
these are unlikely to fit your needs exactly but include useful hints
[1]: https://git.sr.ht/~serhei/sysprof-experiments/log/serhei/samples-via-fifo
[2]: https://git.sr.ht/~serhei/config-files/tree/master/item/setup-development.md#1b-setup-for-codesysprofcode-development-with-codejhbuildcode-providing-upstream-gnome-apps-to-test-against
Invoking `eu-stacktrace`:
- mkfifo /tmp/test.fifo
- eu-stacktrace </tmp/test.fifo >test.syscap &
- sysprof-cli --use-fifo=/tmp/test.fifo test.syscap
## TODO
- initial version of packet parsing for sysprof
- sysprof should fork eu-stacktrace and pipe info via stdin/stdout
- implement --mode=none
- implement --mode=naive
- implement --mode=caching
- testsuite
- implement --format=perf; make sysprof headers optional through configury
- ?? perhaps support for converting between input/output formats
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