Re: make install getting slower

Hi,

On 2018-12-04 12:31:48 -0800, Andres Freund wrote:
> best of three of
> time make -s install INSTALL=/bin/true
>
> 9.3: 1.53s
> 9.4: 1.55s
> 9.5: 1.90s
> 9.6: 2.10s
> 10: 2.45s
> 11: 2.81s
> master: 2.99s
>
> Obviously a part of that can be explained by the tree getting bigger,
> but that can't be all of it.
>
> It also gets a bit worse if LLVM is enabled (due to the bitcode files
> getting installed), but that's "just" 0.3s for me. We should optimize
> that for fewer install invocations / using cp, but that seems seperate.
>
> I think this also has gotten more pronounced with newer OS versions, as
> the overhead of the spectre/meltdown mitigations have increased the cost
> of syscalls and forks.
>
> Obviously this doesn't terribly matter for actual installations, but I
> do find it fairly annoying when running regression tests...

As a comparison, I'd a tree that had the cmake patchset applied around
(~1.5 yo tree). Using the ninja generator gets a clean build to
0m0.073s, a first install to 0m0.201s and a repeat install to 0m0.170s.

Greetings,

Andres Freund