Nail down Unknown vs Known function calls - Githubissues

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The Haskell Optimization Handbook

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Nail down Unknown vs Known function calls #107

Open doyougnu opened 5 months ago

doyougnu commented 5 months ago

We have a decent overview of this now, but we really should have a much more robust section (probably in the STG chapter #14) that covers:

known vs unknown functions: across different boundaries: modules, packages
fast and slow stg applies, genutils
how to check for known and unknown (prof report)
performance consequences of exporting a function from a module
How these interact with interface files
probably something about unfoldings

Some resources:

https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/rts/haskell-execution/function-calls
https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/rts/haskell-execution/calling-convention
the eval-apply paper. This is where a lot of the theory gets covered for the STG maching (besides SPJ's book) but we need to know the implementation to really understand the performance consequences.

Basically, as a user of GHC I want to:

understand the consequences of exporting a function with respect to runtime performance.

doyougnu commented 2 months ago

the generic apply functions are referenced in the upcoming perf chapter because they crop up during a conversation about PAPs and info tables. Be sure to refine the link for this ticket.

[ ] update the perf chapter