Gabriele Svelto (gabriele.svelto.delete@this.gmail.com) on November 23, 2020 5:36 am wrote:
> I_vs (ivs.delete@this.anon.com) on November 23, 2020 4:58 am wrote:
> > What is the build time on native macOS?
>
> I haven't done a non-incremental build on a mac in a long time, on my not-really-recent
> MacBook Air a full clobber build takes over two hours IIRC.
>
> > Is it possible that what you measure here is the impact
> > of the macOS running as a guest (which has never really been an intended use case)?
>
> I disable paravirtualization for both operating systems in the test so neither had any special benefit.

I just did my own test. Since I couldn't get Firefox dependencies to install correctly on my Mac ( ./mach bootstrap bugs out), I tried building LLVM. I used my Mac laptop (16" MacBook Pro) vs. a similarly configured cloud HPC instance from my workplace (a major university). Here are the specs:

Mac:
- 8-core i9-9980HK (2.4Ghz base clock)
- 16GB DDR4 2667 Mhz
- Xcode 12.2
- macOS 11.0.1

Linux:
- 8-core VM via Xeon Gold 6126 (12 cores, 2.4Ghz base clock)
- 32GB DDR4 2667 Mhz
- Clang 10.0
- Ubuntu 20.04

As you can see, not a 100% match, but ok for an approximate comparison. If anything, the cloud VM should be more performant due to higher clock, higher cache and the fact that it's a HPC CPU. After all, we are comparing a 2kg laptop on my desk to a rack-mounted HPC server in a climate-controlled facility. Xcode 12 should be using LLVM 10 internally, so the compiler should be more or less comparable as well.

I have grabbed the latest revision from llvm-project and built it with `cmake -G "Unix Makefile" ../llvm; make -j 8`. Here are the results:

Mac:
Executed in 22.49 mins fish external
usr time 139.15 mins 155.00 micros 139.15 mins
sys time 7.41 mins 631.00 micros 7.41 mins

Linux:
real 22m3.026s
user 151m41.426s
sys 9m20.096s