Highlights

One runner binary

codspeed exec and the memory instrument no longer download a separate tool on their first run: exec-harness and memtrack now ship inside the runner (#531).

Configurable walltime unwinding

--walltime-unwinding-mode and --walltime-stack-sample-size (or CODSPEED_WALLTIME_UNWINDING_MODE and CODSPEED_WALLTIME_STACK_SAMPLE_SIZE) set how walltime profiles unwind stacks. --perf-unwinding-mode keeps working as a deprecated alias (#586).

Experimental

• Simulation: --experimental-rep-bulk-cost (or CODSPEED_EXPERIMENTAL_REP_BULK_COST), combined with --cycle-estimation, prices amd64 rep movs and rep stos copies from measured bulk costs instead of per element (#620, #60).
• --mode telemetry collects the OpenTelemetry spans and logs your benchmarks export and uploads them with the results. Combine it with a measuring mode, e.g. --mode telemetry,walltime (#589).

Fixes

• Simulation: report the correct main thread stack size to programs (#62).
• Walltime: Go and Java benchmarks on Linux use frame-pointer unwinding whichever profiler runs (#603).
• Walltime and Memory: glibc frames keep the same name across runs, so differential flamegraphs no longer flag them as new or dropped (#601).
• Exec: Node.js analysis runs use the same V8 flags as the codspeed-node integration (#595).
• Run: codspeed run -- <command> <args> keeps each argument as your shell parsed it, so a quoted a|b is no longer split into a pipe. Shell syntax spread across several arguments must now be one quoted string (#622).
• Security: bump rustls-webpki to address RUSTSEC-2026-0382 and RUSTSEC-2026-0383 (#607).

Release Notes

🚀 Features

• Add --experimental-rep-bulk-cost flag (#620) by @not-matthias in #620
• Add codspeed-write-benchmarks skill by @not-matthias
• Collect the OTLP data exported by the benchmarks (#589) by @lvaroqui in #589
• Declare benchmarks run in another process by @lvaroqui in #531
• Bundle memtrack into the runner binary by @GuillaumeLagrange
• Bundle exec-harness into the runner binary by @GuillaumeLagrange
• Track subprocesses instead of preloading a library by @GuillaumeLagrange
• Add --walltime-unwinding-mode with DWARF stack size by @not-matthias

🐛 Bug Fixes

• Quote each argument of a multi-argument command (#622) by @not-matthias in #622
• Compile node analysis workloads eagerly with sparkplug (#595) by @not-matthias in #595
• Infer Go and Java unwinding for both profilers by @not-matthias in #603
• Bump merged sampler and align unwinding arguments by @not-matthias in #586
• Pass stack sample size as --unwinding-stack-size by @not-matthias
• Install libc6-dbg during memory and walltime setup (#601) by @not-matthias in #601

💼 Other

• Inline aarch64 atomics in musl C code instead of linking libgcc by @adriencaccia
• Support building against musl by @GuillaumeLagrange
• Bump rustls-webpki and webpki root certs (#607) by @GuillaumeLagrange in #607
• Bump j178/prek-action from 2.0.4 to 3.0.0 (#495) by @dependabot[bot] in #495

🏗️ Refactor

• Move the CLI into the library by @GuillaumeLagrange
• Scope the rolling buffer display to the run environment (#506) by @GuillaumeLagrange in #506

📚 Documentation

• Mention benchmark writing in the plugin description by @not-matthias in #621
• Point optimize at codspeed-write-benchmarks by @not-matthias
• Point setup-harness at codspeed-write-benchmarks by @not-matthias

⚡ Performance

• Read the memtrack event stream through a 1 MiB buffer (#616) by @not-matthias in #616

🧪 Testing

• Run the executor tests in release by @GuillaumeLagrange

⚙️ Internals

• Bump pinned valgrind-codspeed to 3.26.0-0codspeed14 (#626) by @adriencaccia in #626
  • fix(callgrind): model REP copies with calibrated bulk costs by @not-matthias in CodSpeedHQ/valgrind-codspeed#60
• Release the runner with dist's defaults (#625) by @adriencaccia in #625
• Bump cargo-dist to 0.34.0 by @GuillaumeLagrange in #623
• Build the macOS release on macos-latest by @adriencaccia
• Run the release build on pull requests by @adriencaccia
• Bump pinned valgrind-codspeed to 3.26.0-0codspeed13 (#618) by @adriencaccia in #618
  • fix(initimg): keep glibc's reported main stack size near RLIMIT_STACK by @not-matthias in CodSpeedHQ/valgrind-codspeed#62
• Prime one shared rust-cache for the ubuntu-26.04 x64 jobs by @GuillaumeLagrange in #608
• Share one rust-cache entry per os across bpf-tests shards by @GuillaumeLagrange

Install codspeed-runner 5.7.0

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/CodSpeedHQ/codspeed/releases/download/v5.7.0/codspeed-runner-installer.sh | sh

Download codspeed-runner 5.7.0

Install codspeed-runner 5.7.0-alpha.1

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/CodSpeedHQ/codspeed/releases/download/v5.7.0-alpha.1/codspeed-runner-installer.sh | sh

Download codspeed-runner 5.7.0-alpha.1

Highlights

Go benchmark times match go test

b.Loop() benchmarks that stop and restart the timer inside an iteration now report all of their timed work. A round previously counted only the time since the most recent StartTimer, so results for those benchmarks will move.

Unsupported go test flags no longer fail the run

go test -p 1 ./... -bench . used to strip -p, parse 1 as a package, and fail with package 1 is not in std after every benchmark had passed. Flags and their values are now dropped together.

Fixed randomness in CPU Simulation

getrandom(), /dev/urandom, AT_RANDOM and hardware RNG instructions now return the same values on every CPU Simulation run, removing one source of run-to-run variance.

Release Notes

🚀 Features

• Always enable deterministic RNG (#600) by @not-matthias in #600

🐛 Bug Fixes

• Quiet expected libbpf warnings in a user namespace (#602) by @GuillaumeLagrange in #602
• Bump go-runner to 1.4.0 (#605) by @adriencaccia in #605
  • fix(cli): drop the value of unsupported go test flags by @not-matthias in CodSpeedHQ/codspeed-go#67
  • fix(go-runner): count all timed segments of a b.Loop() iteration by @not-matthias in CodSpeedHQ/codspeed-go#69

Install codspeed-runner 5.6.3

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/CodSpeedHQ/codspeed/releases/download/v5.6.3/codspeed-runner-installer.sh | sh

Download codspeed-runner 5.6.3

Fixes

• Simulation: fix SIGILL on arm64 when programs read previously unsupported CPU ID registers or TPIDRRO_EL0 (#59).
• Go: benchmarks that draw from the global math/rand now start from the same seed on every run, so their results no longer vary between runs (#596).

Release Notes

🚀 Features

• Seed Go's global math/rand deterministically (#596) by @not-matthias in #596

⚙️ Internals

• Bump pinned valgrind-codspeed to 3.26.0-0codspeed12 (#604) by @adriencaccia in #604
  • feat: add --deterministic-rng to make client randomness reproducible by @not-matthias in CodSpeedHQ/valgrind-codspeed#54
  • feat(vex): serve arm64 RNDR and RNDRRS with --deterministic-rng by @not-matthias in CodSpeedHQ/valgrind-codspeed#56
  • fix(vex): decode arm64 MRS of all EL0-visible ID registers by @not-matthias in CodSpeedHQ/valgrind-codspeed#59

Install codspeed-runner 5.6.2

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/CodSpeedHQ/codspeed/releases/download/v5.6.2/codspeed-runner-installer.sh | sh

Download codspeed-runner 5.6.2

Install codspeed-runner 5.6.2-alpha.1

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/CodSpeedHQ/codspeed/releases/download/v5.6.2-alpha.1/codspeed-runner-installer.sh | sh

Download codspeed-runner 5.6.2-alpha.1

Fixes

• Walltime: the runner no longer hangs after the benchmark exits when a Python process forks and leaves a corrupted perf jitdump (#599)
• Simulation: stop the libpython symlink warning from firing falsely (#594)

Release Notes

🐛 Bug Fixes

• Stop the libpython symlink warning from firing falsely by @not-matthias in #594

💼 Other

• Bump submodule to not loop on corrupted jit dump by @GuillaumeLagrange in #599

⚙️ Internals

• Bump CodSpeedHQ/action to v5.6.0 (#597) by @not-matthias in #597

Install codspeed-runner 5.6.1

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/CodSpeedHQ/codspeed/releases/download/v5.6.1/codspeed-runner-installer.sh | sh

Download codspeed-runner 5.6.1

Highlights

More consistent CPU Simulation results

Changes to your CI environment, like a different path or an extra environment variable, no longer change the performance. Each benchmark now starts with the same memory layout, reducing the chance of false regressions.

Release Notes

🐛 Bug Fixes

• Keep the user's HOME when wrapping commands with sudo (#588) by @lvaroqui in #588

🏗️ Refactor

• Spawn child processes with tokio::process (#587) by @lvaroqui in #587

⚙️ Internals

• Bump pinned valgrind-codspeed to 3.26.0-0codspeed10 (#593) by @adriencaccia in #593
  • style: restore upstream trailing whitespace by @lvaroqui in CodSpeedHQ/valgrind-codspeed#51
  • fix(callgrind): suppress L3 warning for explicit LL settings by @not-matthias in CodSpeedHQ/valgrind-codspeed#52
  • fix(initimg): stabilize Linux startup stack layout by @not-matthias in CodSpeedHQ/valgrind-codspeed#53

Install codspeed-runner 5.6.0

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/CodSpeedHQ/codspeed/releases/download/v5.6.0/codspeed-runner-installer.sh | sh

Download codspeed-runner 5.6.0

This release adds support for Ubuntu 26.04, on both x86_64 and arm64. The officially supported distributions are now Ubuntu 22.04, 24.04 and 26.04, and Debian 12.

Profile uploads are also faster on GitHub-hosted runners, and archives larger than 5 GiB can now be uploaded.

Results from the Memory instrument are processed much faster and with less memory on large benchmarks.

This release also fixes a crash that could affect some pytest-codspeed benchmarks since v5.4.2.

Release Notes

🚀 Features

• Split profile archive uploads into concurrent parts (#565) by @lvaroqui in #565

🐛 Bug Fixes

• Only set PYTHONPERFSUPPORT for exec-harness benchmarks (#584) by @not-matthias in #584

🏗️ Refactor

• Move the module event filter next to the decoder by @not-matthias

⚡ Performance

• Use mimalloc as the runner's global allocator by @not-matthias
• Stream each memtrack frame when finding module events by @not-matthias in #578
• Decode memtrack frames for module events in parallel by @not-matthias

🧪 Testing

• Run the memtrack benches on mimalloc by @not-matthias in #581
• Search artifacts of up to 100M events in the module event bench by @not-matthias
• Keep instrumented module event benches to 1M events by @not-matthias in #576
• Benchmark finding module events in a memtrack artifact by @not-matthias

⚙️ Internals

• Support Ubuntu 26.04 (#574) by @lvaroqui in #574
• Publish executable hashes and refresh the eBPF allowlist on release (#585) by @GuillaumeLagrange in #585
• Migrate to github default arm runners (#583) by @lvaroqui in #583

Install codspeed-runner 5.5.0

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/CodSpeedHQ/codspeed/releases/download/v5.5.0/codspeed-runner-installer.sh | sh

Download codspeed-runner 5.5.0

Install codspeed-runner 5.4.3-alpha.1

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/CodSpeedHQ/codspeed/releases/download/v5.4.3-alpha.1/codspeed-runner-installer.sh | sh

Download codspeed-runner 5.4.3-alpha.1

Fixes flamegraphs for Python in simulation mode in the exec CLI.

Release Notes

🐛 Bug Fixes

• Always set PYTHONPERFSUPPORT (#577) by @not-matthias in #577

⚙️ Internals

• Pin exec-harness 1.4.1 (#580) by @adriencaccia in #580

Install codspeed-runner 5.4.2

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/CodSpeedHQ/codspeed/releases/download/v5.4.2/codspeed-runner-installer.sh | sh

Download codspeed-runner 5.4.2