CI Utilisation and system efficiency

Tue May 6 10:26:30 BST 2025

On Tue, May 6, 2025 at 5:36 AM Volker Krause <vkrause at kde.org> wrote:

> On Freitag, 2. Mai 2025 22:55:34 Mitteleuropäische Sommerzeit Ben Cooksley
> wrote:
> > On Sat, May 3, 2025 at 8:26 AM Christoph Cullmann <christoph at cullmann.io
> >
> >
> > wrote:
> > > On Friday, May 2nd, 2025 at 22:18, Ben Cooksley <bcooksley at kde.org>
> wrote:
> > >
> > > On Sat, May 3, 2025 at 3:27 AM Christoph Cullmann <
> christoph at cullmann.io>
> > >
> > > wrote:
> > >> Hi,
> > >>
> > >> at work we use cmake unity build to save time & costs.
> > >>
> > >> Would that be some idea here, too?
> > >>
> > >> Naturally as side effect that can hide compile issues
> > >> or introduce ones.
> > >
> > > We could look into that, just not sure how it would save compile times
> > > though?
> > > We have extremely fast NVMe storage on the builders, so we're unlikely
> to
> > > be IO constrained.
> > >
> > >
> > > Hi,
> > >
> > > that saves more compute power than IO, you parse headers just 1/x of
> the
> > > time for x sized units
> > > and you spawn just 1/x of the processes, at work, that leads to 2 or 4
> > > times the speed, on bare metal
> > > machines with only SSDs, too.
> > >
> > > But naturally that will depend on the projects.
> >
> > I see. Based on the CMake documentation it sounds like something that
> > doesn't always work so i'm hesitant to enable it as a global flag.
> > The CI system through the option cmake-options in .kde-ci.yml can allow
> for
> > the necessary unity build flags to be passed - so this is something heavy
> > users with lots of files may want to look into.
>
> Right, this is probably not a suitable default.
>
> What might be worth exploring though is using unity builds for QML
> cachegen
> code by default. That's many somewhat uniform and predictable files with
> the
> same includes etc. And at least for several things in the top 20 those
> files
> are a significant part of the cost.
>

This sounds like something that needs to be sorted within ECM / Frameworks
/ the applications themselves though and isn't something that can be done
at a global CI level?

>
> Regards,
> Volker
>

Cheers,
Ben

>
> > >> On Friday, April 18th, 2025 at 21:25, Ben Cooksley <bcooksley at kde.org
> >
> > >> wrote:
> > >>
> > >> Hi all,
> > >>
> > >> Over the past week or two there have been a number of complaints
> > >> regarding CI builder availability which i've done some investigating
> into
> > >> this morning.
> > >>
> > >> Part of this is related to the Windows CI builders falling offline
> due to
> > >> OOM events, however the rest is simply due to a lack of builder time
> > >> availability (which is what this email is focused on).
> > >>
> > >> Given we have 6 Hetzner AX51 servers connected to Gitlab (each
> equipped
> > >> with a Ryzen 7 7700 CPU, 64GB RAM and NVMe storage) the issue is not
> > >> available build power - it is the number of builds and the length of
> > >> those
> > >> builds that is at issue.
> > >>
> > >> This morning I ran a basic query to ascertain the top 20 projects for
> CI
> > >> time utilisation on invent.kde.org which revealed the following:
> > >>
> > >> full_path | time_used | job_count
> > >> ------------------------------+------------------+-----------
> > >> plasma/kwin | 320:47:04.966412 | 2387
> > >> graphics/krita | 178:03:19.080763 | 423
> > >> multimedia/kdenlive | 174:08:09.876842 | 697
> > >> network/ruqola | 173:17:47.311305 | 555
> > >> plasma/plasma-workspace | 155:10:03.618929 | 660
> > >> network/neochat | 138:03:23.926652 | 1546
> > >> education/kstars | 129:49:17.74229 | 329
> > >> sysadmin/ci-management | 111:21:09.739792 | 154
> > >> plasma/plasma-desktop | 108:56:52.849433 | 776
> > >> kde-linux/kde-linux-packages | 81:00:10.001937 | 33
> > >> kdevelop/kdevelop | 59:40:51.54474 | 217
> > >> office/kmymoney | 54:32:00.24623 | 271
> > >> frameworks/kio | 53:54:19.046685 | 690
> > >> education/labplot | 52:36:30.343671 | 245
> > >> murveit/kstars | 52:32:56.882728 | 128
> > >> frameworks/kirigami | 47:07:19.172935 | 1627
> > >> system/dolphin | 46:09:58.02836 | 705
> > >> kde-linux/kde-linux | 39:25:54.052469 | 46
> > >> utilities/kate | 36:09:22.18958 | 356
> > >> wreissenberger/kstars | 35:58:14.120515 | 105
> > >>
> > >> If we look closely, KStars has three spots on this list (totalling 216
> > >> hours of time used, making it the biggest app user of CI time).
> > >>
> > >> Projects on the above list are asked to please review their jobs and
> how
> > >> they are conducting development to ensure CI time is used efficiently
> and
> > >> appropriately.
> > >>
> > >> Other projects should also please review their usage and optimise
> > >> accordingly even if they're not on this list as there is efficiencies
> to
> > >> be
> > >> found in all projects.
> > >>
> > >> When reviewing the list of CI builds projects have enabled, it is
> > >> important to consider to what degree your project benefits from having
> > >> various builds enabled. One common pattern i've seen is having Alpine,
> > >> SUSE
> > >> Qt 6.9 and SUSE Qt 6.10 all enabled.
> > >>
> > >> If you need to verify building on Alpine / MUSL type systems and wish
> to
> > >> monitor for Qt Next regressions then you probably shouldn't have a
> > >> conventional Linux Qt stable build as those two jobs between them
> already
> > >> cover that list of permutations.
> > >>
> > >> I've taken a quick look at some of these and can suggest the
> following:
> > >>
> > >> KWin: it has two conventional Linux jobs (suse_qt69 and suse_qt610)
> plus
> > >> a custom reduced feature set job. It seems like one of these
> conventional
> > >> Linux jobs should be dropped.
> > >>
> > >> KStars: Appears to have a custom Linux job in addition to a
> conventional
> > >> Linux job. Choose one please.
> > >>
> > >> Ruqola: Appears to be conducting a development process whereby changes
> > >> are made in stable then immediately merged to master in a ever
> continuing
> > >> loop. Please discontinue this behaviour and only periodically merge
> > >> stable
> > >> to master.
> > >>
> > >> Also needs to drop one of it's Linux jobs as they're duplicating
> > >> functionality as noted above.
> > >>
> > >> Plasma Workspace/Desktop: At least in part this seems to be driven by
> > >> Appium tests. Please reduce the number of these and/or streamline the
> > >> process for running an Appium test. Consideration should be given to
> > >> enabling the CI option use-ccache as well.
> > >>
> > >> KDevelop: Please enable the CI option use-ccache.
> > >>
> > >> Labplot: Appears to have a strange customisation in place to the
> standard
> > >> jobs which shouldn't be necessary as flags in .kde-ci.yml should
> permit
> > >> that to be done.
> > >>
> > >> Thanks,
> > >> Ben
>
>
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