Deduplicate walltime perf symbols, unwind data and debug info across pids by GuillaumeLagrange · Pull Request #240 · CodSpeedHQ/codspeed

GuillaumeLagrange · 2026-02-11T14:44:04Z

Merge/deployment

Merge feat(runner-shared): add new fields to perf metadata #246 (on top of which this PR is based)
Merge the backend PR refering to the changed perf metadata changes
Merge this pr and release runner once the changes in the backend are in prod

Content

Since the real deduplicator source of truth is actually the path of the elf file on disk, I settled on

{path_index}__{file_name}.unwind_data
{path_index}__{file_name}.symbols.map

it allows for the filename to be determined by the actual path, without having to either nest all the files, or have to sanitize paths to file name and end up in awkward file-name length limitations

Here's what it looks like on a 1000 iterations report of one simple program

$ ls
0__exec-harness.symbols.map          3__ld-linux-x86-64.so.2.unwind_data  7__nix-ld.symbols.map         perf.metadata
0__exec-harness.unwind_data          4__ld-linux-x86-64.so.2.symbols.map  7__nix-ld.unwind_data         perf.pipedata
1__libm.so.6.symbols.map             4__ld-linux-x86-64.so.2.unwind_data  8__libc.so.6.symbols.map      results
1__libm.so.6.unwind_data             5__libgcc_s.so.1.symbols.map         8__libc.so.6.unwind_data      runner.log
2__graph-benchmark.symbols.map       5__libgcc_s.so.1.unwind_data         9__libgcc_s.so.1.symbols.map
2__graph-benchmark.unwind_data       6__libc.so.6.symbols.map             9__libgcc_s.so.1.unwind_data
3__ld-linux-x86-64.so.2.symbols.map  6__libc.so.6.unwind_data             ExecutionTimestamps.msgpack

codspeed-hq · 2026-02-11T14:48:06Z

Merging this PR will not alter performance

✅ 4 untouched benchmarks

_{Comparing cod-2138-deduplicate-perf-maps-and-unwind_data (642e4fd) with runner-shared-deduplication-changes (54f94be)}

not-matthias

I think the struct naming can be clarified a bit, I was struggling quite a lot to understand how they map together. Maybe also using custom types for the key that's used in the hashmaps.

The overall logic looks good! Next round should be quick

crates/runner-shared/src/metadata.rs

...apshots/codspeed_runner__executor__wall_time__perf__unwind_data__tests__cpp_unwind_data.snap

src/executor/wall_time/perf/parse_perf_file.rs

src/executor/wall_time/perf/perf_map.rs

src/bin/compare_walltime_output.rs

build.rs

not-matthias

LGTM overall. Just a few minor stylistic comments.

src/executor/wall_time/perf/mod.rs

src/executor/wall_time/perf/parse_perf_file.rs

src/executor/wall_time/perf/unwind_data.rs

This fixes a regression introduced in 8b37208. We now filter pids using `bench_pids`, except for `exec-harness` integrations, where we take all pids.

- Store pid-agnostic data in a file or json map under a mapped `path_key` for each elf - For each pid, store pid specific data, mostly the computed load_bias from where each module was loaded into memory at runtime, alongside a key to retrieve the pid-agnostic data This way, we only write to disk relevant parts of the information.

Also add a rebuild trigger to make it easier to run GITHUB_ACTIONS=1 cargo test` locally. We could have a better trigger, but this will do for now.

art049

Just the naming thing TBD
Otherwise, lgtm! this needs extensive testing before release though

art049 · 2026-02-17T10:40:11Z

src/executor/wall_time/perf/save_artifacts.rs

+/// Register a path in the map if absent, assigning a new unique key.
+/// Returns the assigned key.
+fn get_or_insert_key(path_to_key: &mut HashMap<PathBuf, String>, path: &Path) -> String {
+    if let Some(key) = path_to_key.get(path) {
+        return key.clone();
+    }
+    let key = naming::indexed_semantic_key(path_to_key.len(), path);
+    path_to_key.insert(path.to_owned(), key.clone());
+    key
+}


I think we loose a bit of info here. IIRC, we ended up saying that hashing the path was a better option no?
I know we iterated quite a lot but here we loose all info about similar prefixes (when in the same path) even if it doesn't happen often

GuillaumeLagrange changed the title ~~Cod 2138 deduplicate perf maps and unwind data~~ Deduplicate walltime perf symbols, unwind data and debug info across pids Feb 11, 2026

GuillaumeLagrange force-pushed the cod-2138-deduplicate-perf-maps-and-unwind_data branch from 99e0ea4 to 1a32faa Compare February 11, 2026 14:45

GuillaumeLagrange force-pushed the cod-2138-deduplicate-perf-maps-and-unwind_data branch 2 times, most recently from 15316f4 to 9305a03 Compare February 12, 2026 03:37

GuillaumeLagrange marked this pull request as ready for review February 12, 2026 08:49

GuillaumeLagrange requested review from art049 and not-matthias February 12, 2026 08:49

GuillaumeLagrange force-pushed the cod-2138-deduplicate-perf-maps-and-unwind_data branch from a3617af to 7f65690 Compare February 12, 2026 11:14

not-matthias requested changes Feb 12, 2026

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GuillaumeLagrange removed the request for review from art049 February 13, 2026 11:04

GuillaumeLagrange force-pushed the cod-2138-deduplicate-perf-maps-and-unwind_data branch 5 times, most recently from 192d2ce to 14cb24f Compare February 13, 2026 16:45

GuillaumeLagrange requested a review from not-matthias February 13, 2026 16:46

GuillaumeLagrange force-pushed the cod-2138-deduplicate-perf-maps-and-unwind_data branch from 14cb24f to 9a7f9bc Compare February 13, 2026 16:55

GuillaumeLagrange requested a review from art049 February 13, 2026 17:29

not-matthias approved these changes Feb 13, 2026

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GuillaumeLagrange force-pushed the cod-2138-deduplicate-perf-maps-and-unwind_data branch 2 times, most recently from e43f420 to f308463 Compare February 16, 2026 11:36

GuillaumeLagrange changed the base branch from main to runner-shared-deduplication-changes February 16, 2026 11:36

GuillaumeLagrange force-pushed the cod-2138-deduplicate-perf-maps-and-unwind_data branch 2 times, most recently from 31d5b35 to 642e4fd Compare February 16, 2026 13:19

GuillaumeLagrange added 4 commits February 16, 2026 14:28

feat: use bench_pids filters when harvesting symbols from perf file

582c2b6

This fixes a regression introduced in 8b37208. We now filter pids using `bench_pids`, except for `exec-harness` integrations, where we take all pids.

feat: skip tests requiring sudo if GITHUB_ACTIONS is not set

8ab7c34

Also add a rebuild trigger to make it easier to run GITHUB_ACTIONS=1 cargo test` locally. We could have a better trigger, but this will do for now.

feat: collect debug info by pid

82a55b9

GuillaumeLagrange force-pushed the cod-2138-deduplicate-perf-maps-and-unwind_data branch from 642e4fd to 82a55b9 Compare February 16, 2026 13:29

GuillaumeLagrange force-pushed the runner-shared-deduplication-changes branch from 54f94be to 5bb49e6 Compare February 16, 2026 13:29

art049 approved these changes Feb 17, 2026

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Deduplicate walltime perf symbols, unwind data and debug info across pids#240

Deduplicate walltime perf symbols, unwind data and debug info across pids#240
GuillaumeLagrange wants to merge 4 commits intorunner-shared-deduplication-changesfrom
cod-2138-deduplicate-perf-maps-and-unwind_data

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Merging this PR will not alter performance

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GuillaumeLagrange commented Feb 11, 2026 •

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