> Let me know what you think, please. Hi Peter, I'd like to see an option choosing between opt-in and opt-out. I'd like to see opt-out because opting all packages in is too much work and will never be done. I can live with the risk. Unless I'm the only one asking for this feature ignore it.
Differences to my implementation: NIX_BUILD_CORES is passed always. Its up to the build script to opt-out. Nothing wrong with that. You only pass one env var. I passed one for both: -j and -l option. Using one env var is probably a good approximation. I don't know yet whether there are real world uses cases where you want to pass both. Eg when IO is very slow you may want to start as much processes as possible so that you still get a nice CPU load. Does this happen in practise? You may want to go back to my reverted implementation and have a look at some opt-outs I made. Often I had to opt-out the install phase only. Does your patch allow that? Eg follow the discussion here again (Ludo saying that -j is important for the build phase only): http://thread.gmane.org/gmane.linux.distributions.nixos.scm/130/focus=4325 I think that Ludo was in favour of having two opt-ins: parallelInstall = true; parallelCheck = true; I (as well as Ludo?) expect these two phases to be the most important. Check phase is not used that often. Yet it can take a lot of time (automake or such). Unfortunately I didn't see a patch of him showing how to read those opt-ins in the nicest way. Probably I'd go for adding this twice: make ... many flags .. $([ -z "$parallelInstall"] || echo $parallelBuildFlags ) (because runMake was considered being too complicated) Of course this would become more complicated if we want to choose between opt-in or opt-out. OT: I looked at my CPU load again when running nixos-rebuild swtich two days ago. It was 1.4 (1,5 and 15min average). However I have 4 cores. So this is less than perfect. I guess building in parallel would have risen the figure to 3 at least. I didn't test it. This estimation is based on the feeling I got when watching nixos build stuff using my patches. Marc Weber _______________________________________________ nix-dev mailing list [email protected] https://mail.cs.uu.nl/mailman/listinfo/nix-dev
