[Bug 2138328] Re: linux-tools: consider linking perf against LLVM

had to revert for now due to ​
https://bugs.launchpad.net/ubuntu/+source/llvm-toolchain-21/+bug/2138890

** Changed in: linux (Ubuntu)
Status: Fix Committed => In Progress

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https://bugs.launchpad.net/bugs/2138328

Title:
linux-tools: consider linking perf against LLVM

Status in linux package in Ubuntu:
In Progress

Bug description:
Currently the perf tool has 3 possible ways of converting addresses into source code line numbers:
- LLVM library
- BFD library
- addr2line executable

In Ubuntu, perf is not built with LLVM or libbfd, so it falls back to using "addr2line". On large binaries this runs extremely slow and gives errors, making it effectively unusable. This is a longstanding issue; for some context and previous reports see
- https://michcioperz.com/post/slow-perf-script/
- https://github.com/flamegraph-rs/flamegraph/issues/74
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=911815
- bug 1894407

The option of linking with BFD was rejected in bug 1894407. The
possibility of linking with LLVM is a newer option, with the upstream
support being added in Sep 2024; see the upstream commit message
describing why it is now recommended as the primary choice:
https://github.com/torvalds/linux/commit/c3f8644c21df9b7db97eb70e08e2826368aaafa0.

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