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

[Christian Gagneraud]

On Thu, 16 May 2019 at 02:01, Christian Gagneraud <chgans at gmail.com> wrote:
>
> 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".

a `du -shc build-dir` would be interesting too.

>
> Chris