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feat(linux): support frame-pointer-only recording - #12
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not-matthias wants to merge 3 commits into
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not-matthias wants to merge 3 commits into
not-matthias wants to merge 3 commits into
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Add --unwinding-mode fp to record kernel callchains without copying user stacks or registers. Keep the existing DWARF recording behavior as the default, including on Android. Apply kernel callchain exclusion after initializing perf flags. Cover CLI selection and callchain-only stack conversion, and document frame-pointer build requirements.
Wait for the sampler to finish task initialization before releasing the preload handshake or resuming an attached task. Otherwise short-lived root processes can exit while their initial threads and libraries are still being read, causing the sampler to panic. Reuse one rendezvous channel for task initialization. Release the accepter after each initialization attempt, including failures, so processes do not remain suspended when sampling stops.
not-matthias
marked this pull request as ready for review
October 13, 2026 15:45
The user stack copied per sample for DWARF unwinding was fixed at 32000 bytes. Expose it as --unwinding-stack-size (default unchanged) so callers can trade profile size for deeper stacks. Values are validated against the kernel's sample_stack_user constraints (8-byte aligned, below 65536).
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TLDR: Add
samply record --unwinding-mode fpto use kernel frame-pointer callchains without copying user stacks or registers (Linux only).dwarfas the default with the existing kernel-FP fallback; preserve FP mode for launch, PID attach, and software-event fallback.cargo test -p samply --locked: 28 passed, one existing ignored test.FP stacks require preserved frame pointers throughout the call chain and remain subject to kernel/architecture support and callchain depth limits.
Refs COD-3861.