[Nix-dev] Re: Another approach at parallelizing in-build jobs

[Peter Simons]

Hi Ludovic,

 >> the Linux kernel, GHC, GCC, glibc, etc.
 >
 > Among the thousands of packages in these distros, it may be that not
 > all of them are as good as the 4 projects you mention.

you are right. As usual, there are conflicting interests. Michael
correctly pointed out, that we'll have to try to achieve some kind of
balance. On one hand, there is the amount of time that can be saved by
building a package with parallel compilation enabled, and on the other
hand, there is the amount of time that is necessary to make that build
work.

For those packages I mentioned, the cost/benefit ratio is extremely
favorable, because there's no significant risk that the builds are
broken, yet, there is a lot of time to be saved by utilizing more than
one core to compile them.

For other packages, that cost/benefit ratio is far worse. Consequently,
I don't believe that we should set out to build *everything* with
parallel compilation enabled. Gentoo and others actually patch the build
system of broken packages to allow doing that. I admire their efforts,
but I wouldn't be willing to do it, and I don't believe that it's
important for NixOS, because we can always utilize inter-package
parallelism at no extra risk at all.

Does that sound like a reasonable approach to you?

Take care,
Peter