KInit - Current state and benchmarks

[Christoph Cullmann]

Hi,

On 2019-06-17 11:56, David Edmundson wrote:
> From API.kde.org:
>> Using kdeinit to launch KDE applications makes starting a typical KDE 
>> applications 2.5 times faster (100ms instead of 250ms on a P-III 500)
> 
> Certainly sounds like a good thing.
> 
> ===The current State===
> 
> ==Plasma==
> * Apps launched from the plasma menu skip klauncher and therefore
> kinit. This was done due to the API for KRun blocking somewhere
> (Though I don't remember details)
> 
> This seems like something easily fixable if we tried.
> 
> * Processes launched on bootup (with the exception of kcminit,
> ksmserver and kded5) skip kinit. This was due to a deadlock in
> klauncher and ksmserver at the time when apps autostart moved from
> frameworks.
> 
> This deadlock is since resolved in my ksmserver splitting branches.
> 
> * But Plasma apps launched from the desktop do go through klauncher
> (and therefore kinit)! So we're not even consistent.
> 
> ==Apps==
> * The number of applications linking kinit properly under KF5 is in an
> equally sorry state.
> Dolphin does, but even core applications like Okular and Kate don't.
I stopped using it I guess to be consistent between all platforms 
shipping Kate.
(beside, if you profile the Kate startup, all things are >>>>> the stuff 
kdeinit saves)

> 
> See
> $ find -name 'CMakeLists.txt' -print0 | xargs -0 grep
> 'kf5_add_kdeinit_executable'
> for a local list.
> 
> * It's also incompatible with flatpak/snaps/appimage, which is a rising 
> trend
> 
> ==Other==
> Kinit is still also used for spawning KIO slaves.
> 
> ===Is it still useful?===
> We're not using it properly and we need to do something. Either fix it
> or start to phase it out officially.
> 
> Since the time of writing kinit Qt has changed a lot. linking has
> changed a bit. CPUs have changed a lot and Hard Disks have changed a
> lot.
> 
> So I wrote a benchmark tool to see if the initial speed boost claim is
> relevant: kde:scratch/davidedmundson/inittimer
> 
> My test does the following:
>  - creates a dummy (headless) wayland server
>  - spawns an app using either QProcess or sending a DBus message to 
> KLauncher
>  - times how long it takes for the first window to appear, timing the
> more important real world metric and one that includes all the
> factors.
> 
> Results:
> (Showing the median out of 5 runs on a mid range SSD desktop)
> 
> Dolphin QProcess: 348
> Dolphin Kinit: 332
> 
> KCalc   QProcess:  242
> KCalc   KInit: 232
> 
> Plasmoidviewer (patched) QProces: 622
> Plasmoidviewer (patched) KInit: 591
> 
> KWrite  QProcess: 391
> KWrite  Kinit: 390
> (unsurprisingly similar as kwrite does not have a kdeinit exec, I
> included it as it shows the others aren't false positives)
> 
> ===What about memory?===
> 
> Good question. It needs a similar investigation by someone who
> understands memory...
> 
> ===Conclusion===
> 
> My test implies there /is/ a genuine saving with kinit !
> However it's far from the claimed 2.5 times faster, it is less than
> 1.1 times faster. Saving up to 30ms.

my opinion: it's not worh the hassle.

Greetings
Christoph

-- 
Ignorance is bliss...
https://cullmann.io | https://kate-editor.org