On Sat, Dec 06, 2025 at 11:50:08AM +0100, Mateusz Guzik wrote:
> II. compilation speed
>
> The the real and serious problem. Both versions of the system ship the
> same clang version:
> FreeBSD clang version 19.1.7 (https://github.com/llvm/llvm-project.git
> llvmorg-19.1.7-0-gcd708029e0b2)
> Target: x86_64-unknown-freebsd14.3
> Thread model: posix
> InstalledDir: /usr/bin
>
> FreeBSD clang version 19.1.7 (https://github.com/llvm/llvm-project.git
> llvmorg-19.1.7-0-gcd708029e0b2)
> Target: x86_64-unknown-freebsd15.0
> Thread model: posix
> InstalledDir: /usr/bin
>
> I found that compiling the will-it-scale suite about doubles in real
> time needed, along with doubling time spent in userspace.
>
> will-it-scale needs a little bit of massaging to work, diff at the end.
>
> check this out (repeabale): while true; do gmake -s clean && time
> gmake -s -j 8; done
>
> 14.3:
> gmake -s -j 8 8.93s user 2.03s system 769% cpu 1.42s (1.424) total
> gmake -s -j 8 9.02s user 2.16s system 757% cpu 1.48s (1.475) total
> gmake -s -j 8 9.29s user 1.95s system 774% cpu 1.45s (1.450) total
> gmake -s -j 8 8.97s user 2.46s system 770% cpu 1.48s (1.484) total
> gmake -s -j 8 9.13s user 2.30s system 773% cpu 1.48s (1.477) total
14.3 clang/lld are probably statically linked, but I am not sure.
Can you confirm this?
>
> 15.0:
> gmake -s -j 8 19.90s user 3.02s system 773% cpu 2.96s (2.963) total
> gmake -s -j 8 19.90s user 3.18s system 774% cpu 2.98s (2.979) total
> gmake -s -j 8 20.24s user 2.90s system 770% cpu 3.00s (3.005) total
> gmake -s -j 8 19.92s user 3.25s system 771% cpu 3.00s (3.003) total
> gmake -s -j 8 20.25s user 2.95s system 772% cpu 3.01s (3.006) total
But 15.0 is definitely dynamically linked.
clang is enormous C++ binary with enormous amount of relocs:
$ ldd /usr/bin/cc
/usr/bin/cc:
libprivateclang.so.19 => /usr/lib/libprivateclang.so.19 (0x27417e200000)
libprivatellvm.so.19 => /usr/lib/libprivatellvm.so.19 (0x274183e00000)
$ objdump -R /usr/lib/libprivateclang.so.19 | wc -l
232977
$ objdump -R /usr/lib/libprivatellvm.so.19 | wc -l
140712
>
> user time *skyrocketed*
