On Sun, Oct 30, 2011 at 09:34:50PM +0100, Vladimír Čunát wrote: > Hi. > > On 26 October 2011 23:47, Paul Dufresne <dufres...@gmail.com> wrote: > > It seems that it need to evaluate all the nix expressions in the > > unstable packages.While doing this, top reports that it eats about 72% > > of my memory (256Mb Physical + 256Mb virtual). > > I'm afraid this is normal behaviour. Performance of nix evaluation > certainly isn't so good, but we seem to have much stronger machines, > so we don't mind so much (there are many other problems). > > And yes, the expressions are evaluated every time, but lazily. > Installing by attribute name instead of package name helps a lot > there, because all the package names have to be evaluated to select by > package name (attribute name select directly). Here's a small test, > measuring physical memory usage (using absolute path for time to > prevent firing bash builtin): > > "/var/run/current-system/sw/bin/time -f %M nix-env -i hello --dry-run" > reports using 1.3 GB RAM (!) > "/var/run/current-system/sw/bin/time -f %M nix-env -iA hello > --dry-run" reports 56 MB RAM
The amount of memory used depends on the RAM available in the system (on a fixed percent of it). There is an env var, GC_INITIAL_HEAP_SIZE, that can make that smaller. I imagine that the particularities of 'boehm-gc' makes this initial allocation work as if there was no 'lazy allocation' in linux, therefore reporting that much ram usage. Regards, Lluís. _______________________________________________ nix-dev mailing list nix-dev@lists.science.uu.nl http://lists.science.uu.nl/mailman/listinfo/nix-dev
