[Qbs] Who compared build times of Qt Creator with CMake and qbs?

[Christian Gagneraud]

On Thu, 16 May 2019 at 01:45, Orgad Shaneh <orgads at gmail.com> wrote:
>
> I compared qbs and cmake/ninja, and got these results (Debug build, no QbsPM and no Clang):
>
> Notice that qbs builds unit tests, which cmake doesn't.
>
> time qbs -f ../qt-creator/qtcreator.qbs profile:qt-5-11-1 modules.cpp.compilerWrapper:ccache
> cold ccache:
> real    5m26.149s
> user    125m3.443s
> sys     16m55.134s
>
> warm cache:
> real    1m40.335s
> user    17m20.419s
> sys     4m12.409s
>
> time cmake ../qt-creator -DCMAKE_CXX_COMPILER_LAUNCHER=ccache -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_BUILD_TYPE=Debug -G Ninja
> real    0m8.256s
> user    0m7.425s
> sys     0m0.827s
>
> time ninja
> cold cache:
> real    5m23.413s
> user    128m25.457s
> sys     16m11.551s
>
> time ninja:
> warm cache:
> real    0m45.964s
> user    7m12.563s
> sys     2m23.616s
>

Thanks for reporting, i'm planning to run my own benchmark as well,
not to state who's the winner, just for curiosity.
One important metric IMHO is the ratio sys/user, as it shows I/O
bottlenecks (esp. relevant when doing debug builds with hot ccache).
In my setup i will use ram disks for ccache and build dir (source dir
has nearly no effects)
It used to be my typical config (had to fight for memory tho), until i
got a new machine with NVRam as mass storage. It's almost as fast as
ramdisks.

As well, please note that the current CMake doesn't build as much
stuff as the qbs one. Not sure the difference is huge, but you need to
compare "equal jobs".

Chris