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Answer: Put a pprof CPU profile named default.pgo in the main package directory and go build uses it automatically.

Versions

• Go 1.20: preview.
• Go 1.21: ready for general production use.

Steps

1. Collect a CPU profile from production using runtime/pprof or net/http/pprof.
2. The standard approach to building is to store a pprof CPU profile with filename default.pgo in the main package directory of the profiled binary. (S1)
3. Build normally; -pgo=auto is the default.

Notes

• PGO is also called feedback-directed optimization (FDO).

Claims

• id: C1 claim: The Go compiler supports PGO starting in Go 1.20. source: S1 evidence: "Starting in Go 1.20, the Go compiler supports profile-guided optimization (PGO) to further optimize builds."
• id: C2 claim: PGO improves performance by around 2-14% as of Go 1.22. source: S1 evidence: "building with PGO improves performance by around 2-14%"
• id: C3 claim: go build detects default.pgo files automatically. source: S1 evidence: "By default, go build will detect default.pgo files automatically and enable PGO."
• id: C4 claim: The compiler uses CPU pprof profiles as input. source: S1 evidence: "In Go, the compiler uses CPU pprof profiles as the input profile"
• id: C5 claim: PGO in Go 1.21 is ready for production use. source: S2 evidence: "PGO support in Go 1.21 is ready for general production use!"

Sources

• [S1] Profile-guided optimization - The Go Programming Language. The Go Authors (go.dev). https://go.dev/doc/pgo . License: CC BY 4.0 (go.dev text). Accessed 2026-11-04.
• [S2] Profile-guided optimization in Go 1.21 - The Go Programming Language. The Go Authors (go.dev). https://go.dev/blog/pgo . License: CC BY 4.0 (go.dev text). Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_q4pqb1nw,
  author = {{iinventedlight}},
  title = {{Profile-guided optimization (PGO) in Go}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/go-profile-guided-optimization/},
  note = {Permanent ID iil:note:q4pqb1nw. License: CC-BY-4.0.},
}

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