Eelco Dolstra
4ccd48ce24
Evaluation of a NixOS configuration spends quite a lot of time in the "filter" function in Nixpkgs. As implemented in Nixpkgs, this is a O(n^2) operation, so it's a good candidate for providing a more efficient (i.e. primop) implementation. Using it gives a ~10% speed increase and a significant reduction in the number of evaluations. Statistics before (on a NixOS system config): time elapsed: 1.3258 size of a value: 24 environments allocated: 1980939 (50127080 bytes) list elements: 14679308 (117434464 bytes) list concatenations: 50828 values allocated: 2098938 (50374512 bytes) attribute sets allocated: 392040 right-biased unions: 186334 values copied in right-biased unions: 591137 symbols in symbol table: 18271 number of thunks: 1645752 number of thunks avoided: 1921196 number of attr lookups: 430798 number of primop calls: 838807 number of function calls: 1930107 Statistics after: time elapsed: 1.17982 size of a value: 24 environments allocated: 1543334 (39624560 bytes) list elements: 9612638 (76901104 bytes) list concatenations: 37434 values allocated: 1854933 (44518392 bytes) attribute sets allocated: 392040 right-biased unions: 186334 values copied in right-biased unions: 591137 symbols in symbol table: 18272 number of thunks: 1392467 number of thunks avoided: 1507311 number of attr lookups: 430801 number of primop calls: 691600 number of function calls: 1492502
Nix is a purely functional package manager. For installation and usage instructions, please read the manual, which can be found in `docs/manual/manual.html', and additionally at the Nix website at <http://nixos.org/>. Acknowledgments This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit (http://www.OpenSSL.org/).