Hi, Great News :)
On Wed, May 12, 2010 at 16:01, Eelco Dolstra <e.dols...@tudelft.nl> wrote: > Hi, > > I've merged the Nix `fast-eval' branch into the trunk. This replaces the > current Nix expression evaluator by a new, faster implementation. It no > longer > uses the term-rewriting based approach (described in [1]) but a more > conventional functional language implementation based on thunk updating. As a > result, Nix no longer depends on the ATerm library. > > Here are some benchmark results to show the performance improvement. The > benchmarks are: > > - `nix-env -f /etc/nixos/nixpkgs -qa \*' on Nixpkgs r21747. > - `nix-env -f /etc/nixos/nixpkgs -qa \* --drv-path'. > - `nix-instantiate /etc/nixos/nixos -A system --readonly-mode' (also on r21747 > of NixOS). This is what every `nixos-rebuild' operation does. > - `nix-instantiate /etc/nixos/nixos/tests/ -A proxy.test --readonly-mode' > (which > evaluates 4 NixOS system configurations). > > These were done on a 32-bit Linux machine (Intel Core 2 Duo T7700 @ 2.40GHz, 2 > GiB RAM) and on a 64-bit Linux machine (Intel Core i5 750 @ 2.67GHz, 6 GiB > RAM). > Here are the timings in seconds: > > | Old | New | Speedup > -----------------------------------------+-------+------+-------- > `nix-env -qa' (32-bit) | 2.96 | 0.60 | 4.9x > `nix-env -qa' (64-bit) | 1.86 | 0.32 | 5.8x > `nix-env -qa --drv-path' (32-bit) | 12.48 | 3.96 | 3.2x > `nix-env -qa --drv-path' (64-bit) | 7.65 | 2.04 | 3.8x > `nix-instantiate -A system' (32-bit) | 6.79 | 1.32 | 5.1x > `nix-instantiate -A system' (64-bit) | 4.63 | 0.71 | 6.5x > `nix-instantiate -A proxy.test' (32-bit) | 23.86 | 3.55 | 6.7x > `nix-instantiate -A proxy.test' (64-bit) | 15.76 | 1.95 | 8.1x > > Another goal of the `fast-eval' branch was to reduce memory consumption by the > evaluator. The old evaluator basically never released memory due to its > normal > form cache. With the new evaluator, we can in principle reclaim garbage > memory. > However, it doesn't actually have a garbage collector yet. I intend to use > the > Boehm GC for that. Nevertheless, the new evaluator already uses less memory > than the old one. For instance, `nix-instantiate -A system' on 64-bit Linux > uses 358.6 MiB with the old evaluator, but only 213.7 MiB with the new > evaluator > (according to Valgrind's `massif' tool). > > [1] http://www.st.ewi.tudelft.nl/~dolstra/pubs/laziness-ldta2008-final.pdf -- Nicolas Pierron http://www.linkedin.com/in/nicolasbpierron - http://nbp.name/ _______________________________________________ nix-dev mailing list nix-dev@cs.uu.nl https://mail.cs.uu.nl/mailman/listinfo/nix-dev
