> On Dec 18, 2014, at 2:17 PM, Garrett Cooper <yaneurab...@gmail.com> wrote: > > On Dec 18, 2014, at 6:51, Warner Losh <i...@bsdimp.com> wrote: > >> With the recent parallelism work, the is true. It might save a couple percent >> off the build time. Before those changes, though, disabling all non target >> arches saved about 10% of the buildworld time. > > I’m curious. How much is 10% in terms of minutes and with what -j value?
That depends on how long the build takes. For my 20 minute builds it was about 2 minutes faster. At the time, -j didn’t really effect build times once you got north of 4 because parallelism really sucked. Now it doesn’t suck and it scales much better and I suspect that the time savings would be tiny because it would be done at the same time as other things anyway, but I’ve not measured it directly. >> Creating a hack to do this is easy (which is how I measured it). But Dimitry >> is right that creating a robust solution is hard. Even harder if you want it >> to be completely clean. > > It didn’t seem incredibly hard — it just required a bit more “generated > files” in clang AFAICT. I’ll hang ten until clang35 is in so I can re-asses > what’s going on with building it. Yea, and that file generation is a pita, or I’d have committed my changes a while ago... >> I tend to agree. IMHO, supporting the work going on to bring the >> meta-mode stuff will pay far higher dividends than optimizing this >> corner of the build. > > True… probably will! Yea, this isn’t a problem worth solving today. Warner
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