> 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 
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 
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.


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