[Interest] Qt 6 is much more faster to compile from source

Konstantin Tokarev annulen at yandex.ru
Tue Sep 7 19:57:38 CEST 2021

07.09.2021, 20:53, "Thiago Macieira" <thiago.macieira at intel.com>:
> On Tuesday, 7 September 2021 02:52:49 PDT Tor Arne Vestbø wrote:
>>  Good to hear!
>>  Part of it comes from CMake generating ninja files instead of Makefiles.
> Our qmake-generated Makefiles weren't that slow. Nothing compared to Automake,
> at least.
> Qt 5 qtbase/src build:
> Build succeeded, took 3:01.027s (total run time 3:01.027s), 2388.2% CPU usage
> Qt 6 equivalent with Ninja:
> Build succeeded, took 222.01s (2385% CPU usage)
> 3:01.027 = 181.027s (sorry, different wrapper, so they print time differently)
> Same compiler, same otherwise-idle machine, icecc disabled. The configuration
> on both builds is meant to be the same, full build.

If generated makefiles were non-recursive, it would be even faster.

Ninja rocks for incremental build times and has some convenience features for
generators, but it's not a magic pill.


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