[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Stephan Karacson]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #158 from Stephan Karacson  ---
I believe it works now without tripleBuffer quite well on kwin 5.15.5 on
Gentoo-GNU/Linux, just to dump a version number here.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Greg C]

https://bugs.kde.org/show_bug.cgi?id=322060

Greg C  changed:

   What|Removed |Added

 CC||android.em...@gmail.com

--- Comment #157 from Greg C  ---
(In reply to Peter Eszlari from comment #154)
> I guess this bug can be closed now:
> 
> https://phabricator.kde.org/D19867

Good day, how can i apply this resolution? what is the resolution

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Nikos Chantziaras]

https://bugs.kde.org/show_bug.cgi?id=322060

Nikos Chantziaras  changed:

   What|Removed |Added

 CC||rea...@gmail.com

--- Comment #156 from Nikos Chantziaras  ---
For anyone coming here through a web search, there's a KWin fork that fixed all
issues for me:

https://github.com/tildearrow/kwin-lowlatency

No more frame skipping or stutter, no more lag, works great with modern,
better-than-60Hz displays.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Martin Flöser]

https://bugs.kde.org/show_bug.cgi?id=322060

Martin Flöser  changed:

   What|Removed |Added

 Resolution|--- |FIXED
 Status|REPORTED|RESOLVED

--- Comment #155 from Martin Flöser  ---
Marking as fixed per latest comment

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Peter Eszlari]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #154 from Peter Eszlari  ---
I guess this bug can be closed now:

https://phabricator.kde.org/D19867

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Babets]

https://bugs.kde.org/show_bug.cgi?id=322060

Babets  changed:

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 CC|bab...@gmail.com|

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Peter Eszlari]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #153 from Peter Eszlari  ---
(In reply to Martin Flöser from comment #152)
> Nvidia needs to know that it is harming their business.

I think they won't care much, because the Linux customers that Nvidia cares
about are running Redhat Enterprise with GNOME.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Martin Flöser]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #152 from Martin Flöser  ---
(In reply to Peter Eszlari from comment #151)
> (In reply to Martin Flöser from comment #148)
> > Feel free to use GNOME if it gives the better experience for you.
> > Unfortunately it is not possible to draw any conclusions from the fact that
> > it works for you on GNOME.
> 
> But than I would have deal with a crippled desktop environment. What I will
> do instead is, I will buy an AMD card. I just don't think such a out of the
> box experience for owners of Nvidia cards is good for KDE.

Please tell Nvidia that you buy a card of a different vendor because their
driver sucks. Nvidia needs to know that it is harming their business. We cannot
and do not want to fix Nvidia's driver issues.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Peter Eszlari]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #151 from Peter Eszlari  ---
(In reply to Martin Flöser from comment #148)
> Feel free to use GNOME if it gives the better experience for you.
> Unfortunately it is not possible to draw any conclusions from the fact that
> it works for you on GNOME.

But than I would have deal with a crippled desktop environment. What I will do
instead is, I will buy an AMD card. I just don't think such a out of the box
experience for owners of Nvidia cards is good for KDE.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #150 from Mahendra Tallur  ---
|OT : to users]

Hi ! I'm sorry for adding noise, I would just like to express a piece of advice
to *users* like me. As it's a longstanding problem affecting many people.

1) there are technical considerations that we cannot grasp ; but numerous
efforts were put in the past, and the very nature of the Nvidia drivers makes
it difficult to solve this problem. Workaround were attempted in the past with
no satisfying result.

2) You can get a semi-acceptable state by applying work-around but it's never
that great. (disabling automatic composition interruption ; enabling triple
buffering)

3) it's not that great either under Gnome. You still get sub-optimal
performance on the desktop (I tried & compared Gnome Shell performance with an
Intel HD) ; you still have to apply tweaks for tearing in some apps (Totem,
browsers for instance). It's acceptable, but that's also a compromise...

4) believe me, the difference in terms of general usability is so huge, it's
worth downgrading and switching to a different GPU vendor, if you're not a big
gamer. I settled with a very slow and cheap AMD RX550. Gaming is OK but desktop
performance is stellar (as it is with Intel HD drivers). No more tearing, no
more KDE panel crash, no workaround. You also benefit from : open source
drivers, Wayland session, Lakka now works and eventually from the realtime-kwin
;-), no tweak, constant 60 FPS desktop...

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Nikos Chantziaras]

https://bugs.kde.org/show_bug.cgi?id=322060

Nikos Chantziaras  changed:

   What|Removed |Added

 CC|rea...@gmail.com|

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Thomas Lübking]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #149 from Thomas Lübking  ---
Or maybe just read https://bugs.kde.org/show_bug.cgi?id=322060#c141 about the
nature of the "bug" and the state of the resolution ...

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Martin Flöser]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #148 from Martin Flöser  ---
(In reply to Peter Eszlari from comment #147)
> What I don't get about this long-standing bug is, that under GNOME
> everything works out of the box - no tearing

Feel free to use GNOME if it gives the better experience for you. Unfortunately
it is not possible to draw any conclusions from the fact that it works for you
on GNOME.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Peter Eszlari]

https://bugs.kde.org/show_bug.cgi?id=322060

Peter Eszlari  changed:

   What|Removed |Added

 CC||peter.eszl...@gmail.com

--- Comment #147 from Peter Eszlari  ---
What I don't get about this long-standing bug is, that under GNOME everything
works out of the box - no tearing. And without having to mess with any
configuration. This suggest to me that the bug is somewhere in kwin.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[matthias sweertvaegher]

https://bugs.kde.org/show_bug.cgi?id=322060

matthias sweertvaegher  changed:

   What|Removed |Added

 CC||matthias.sweertvaegher@gmai
   ||l.com

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #146 from Mahendra Tallur  ---
@Nikos : the link is available now :
https://devtalk.nvidia.com/default/topic/1029568/linux/the-situation-on-kde-kwin-plasma-performance/

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #145 from Mahendra Tallur  ---
It does exist, for some reason it seems to be hidden. Maybe NVIDIA has to
approve of it first. Sorry for the inconvenience. It seems many other users
have the same issue on this forum.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Nikos Chantziaras]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #144 from Nikos Chantziaras  ---
(In reply to Mahendra Tallur from comment #143)
> As suggested, I finally created a thread on the NVIDIA forum where an NVIDIA
> dev frequently replies... A message in a bottle !
> 
> https://devtalk.nvidia.com/default/topic/1029568/linux/the-situation-on-kde-
> kwin-plasma-performance/

That link doesn't seem to work. I can't see any such thread there.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #142 from Mahendra Tallur  ---
As suggested, I finally created a thread on the NVIDIA forum where an NVIDIA
dev frequently replies... A message in a bottle !

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #143 from Mahendra Tallur  ---
As suggested, I finally created a thread on the NVIDIA forum where an NVIDIA
dev frequently replies... A message in a bottle !

https://devtalk.nvidia.com/default/topic/1029568/linux/the-situation-on-kde-kwin-plasma-performance/

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Thomas Lübking]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #141 from Thomas Lübking  ---
As pointed out in the original report, this has *never* been about vsync
functionality per se.

The other yield methods (at that time, I dropped KDE for other reasons) caused
ridiculous CPU load (when glSwapBuffers block, ie. w/ double buffered vsync).
So the code just checks for the environment to be set and disables vsync if
it's not and the triple buffering is guessed (there is/was no way to query it)
off.

Tuhs it would be good if one could ensure kwin to be loaded w/ this setting,
but setting the environment in the process is too late.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Lastique]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #140 from Lastique  ---
BTW, in that Nvidia thread, a driver developer says:

> The claim that __GL_YIELD=usleep is required points at an application bug, 
> possibly a race condition due to missing synchronization.

So if anyone is fixing tearing by that option (i.e. the tearing is present
without it and not present with it), then, according to Nvidia, the bug is in
Kwin.

On my system though, __GL_YIELD=usleep has no influence on tearing, only on CPU
consumption.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Lastique]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #139 from Lastique  ---
(In reply to Mahendra Tallur from comment #137)
> 
> I see another issue when using Force(Full)CompositionPipeline : about one
> time out of two, I get a black desktop (no plasmoid / background) until the
> next reboot.

This may be a manifestation of the infamous "black textures" problem.

https://bugs.kde.org/show_bug.cgi?id=386752
https://devtalk.nvidia.com/default/topic/1026340/linux/black-or-incorrect-textures-in-kde

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #138 from Mahendra Tallur  ---
Oops forgot this to my previous comment (when I get a black desktop in 50% of
the cases when forcing the pipeline) : 

the desktop is black but when I move the mouse over it and right click, the
menu is related to the items that were supposed to be there ; for instance, the
properties of a specific desktop icon in a specific folder view...

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #137 from Mahendra Tallur  ---
I second Ryein & Nikos regarding the previous-buffer issue. Also I managed but
that's offtopic to kill kwin by switching back and forth from a game that
interrupted composition and the desktop. (that's probably another story and
I'll check with the new plasma)

Thanks for taking the time to reply, Thomas. 

I see another issue when using Force(Full)CompositionPipeline : about one time
out of two, I get a black desktop (no plasmoid / background) until the next
reboot. I get the bottom panel and everything else works though. Also, even
though the value is set in xorg.conf, it add an 15 seconds delay on a black
screen (after X start / before plasma appears).

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Thomas Lübking]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #136 from Thomas Lübking  ---
The full composition pipeline indirects rendering in the driver. It's implicit
when eg. xrandr scaling the output or so.

As for the "not what you said" comment, I focused on the "old wallpaper" thing.
I didn't read the description as "all of plasmashell freezes to an old buffer"

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #135 from Mahendra Tallur  ---
Regarding the Force(Full)CompositionPipeline VERSUS setting GL_YIELD to USLEEP. 
I used to use the latter and not the former because forcing the composition
pipeline may slow down the system / induce more power consumption etc. or so I
thought.

With any of the solutions, tearing is fixed. When using USLEEP I felt there was
a performance impact on the desktop : for instance, it's obvious when moving a
window to the edge of the screen to maximize it : it's jerky when using USLEEP
with an nvidia card (but it's butter smooth with my Intel HD Graphics).

I figured out this animation is also smooth when using
Force(full)compositionpipeline. I'm not 100% sure about the other effects, but
it seems better. General desktop usage still seems slightly less smooth than
with open source drivers, but it's better than when using USLEEP.

As for forcing the FULL composition pipeline or not, I don't know what actual
difference it makes.

(sorry for adding more noise :-)

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Nikos Chantziaras]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #134 from Nikos Chantziaras  ---
(In reply to Thomas Lübking from comment #132)
> > and the time on the systray says "20:00", but the time now is 21:00
> That's not what you said :-P
> 
> https://bugs.kde.org/show_bug.cgi?id=353983

I don't see any post from me on that bug :-P

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Ryein Goddard]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #133 from Ryein Goddard  ---
huh?


On 02/01/2018 10:57 AM, Thomas Lübking wrote:
> https://bugs.kde.org/show_bug.cgi?id=322060
>
> --- Comment #132 from Thomas Lübking  ---
>> and the time on the systray says "20:00", but the time now is 21:00
> That's not what you said :-P
>
> https://bugs.kde.org/show_bug.cgi?id=353983
>

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Thomas Lübking]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #132 from Thomas Lübking  ---
> and the time on the systray says "20:00", but the time now is 21:00
That's not what you said :-P

https://bugs.kde.org/show_bug.cgi?id=353983

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Ryein Goddard]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #131 from Ryein Goddard  ---
That sounds like exactly what I experience.  I guess the Nvidia driver 
is doing this?


On 02/01/2018 10:28 AM, Nikos Chantziaras wrote:
> https://bugs.kde.org/show_bug.cgi?id=322060
>
> --- Comment #130 from Nikos Chantziaras  ---
> (In reply to Thomas Lübking from comment #128)
>>> My wallpaper even reverts back to some previous datetime's image.
>> That I cannot explain at all.
> This is reproducible by simply suspending compositing. After an undetermined
> amount of time, the non-composited desktop will freeze its appearance and will
> not get updated anymore. New applications don't appear on the task manager 
> bar,
> the system tray doesn't get updated, basically it's frozen to some state in 
> the
> past.
>
> Resuming compositing again makes it work correctly. Suspending compositing
> after that makes it revert to the same old frozen state. For example, if it 
> got
> frozen and the time on the systray says "20:00", but the time now is 21:00,
> then suspending and resuming compositing makes it display 20:00 - 21:00 - 
> 20:00
> - 21:00, etc, as you suspend/resume compositing.
>

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Serhiy Zahoriya]

https://bugs.kde.org/show_bug.cgi?id=322060

Serhiy Zahoriya  changed:

   What|Removed |Added

 CC|serhiy@gmail.com|

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Nikos Chantziaras]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #130 from Nikos Chantziaras  ---
(In reply to Thomas Lübking from comment #128)
> > My wallpaper even reverts back to some previous datetime's image.
> That I cannot explain at all.

This is reproducible by simply suspending compositing. After an undetermined
amount of time, the non-composited desktop will freeze its appearance and will
not get updated anymore. New applications don't appear on the task manager bar,
the system tray doesn't get updated, basically it's frozen to some state in the
past.

Resuming compositing again makes it work correctly. Suspending compositing
after that makes it revert to the same old frozen state. For example, if it got
frozen and the time on the systray says "20:00", but the time now is 21:00,
then suspending and resuming compositing makes it display 20:00 - 21:00 - 20:00
- 21:00, etc, as you suspend/resume compositing.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Ryein Goddard]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #129 from Ryein Goddard  ---
I don't think that is the case because it happens when using CUDA 
outside of games in some projects I work on.


On 02/01/2018 10:16 AM, Thomas Lübking wrote:
> https://bugs.kde.org/show_bug.cgi?id=322060
>
> --- Comment #128 from Thomas Lübking  ---
>> Plasma freezes for a moment and then all advanced graphics appear frozen.
> Sounds just as if steam blocks/disables the compositor?
>
>> My wallpaper even reverts back to some previous datetime's image.
> That I cannot explain at all.
>
>> when opening any app while a video is playing underneath makes the video 
>> stutter
> This is either by the opening animation (crucial?) and the video running at
> different FPS or (rather?) I/O related (in this case different "apps" will 
> have
> different impact)
>
>> which doesn't open with an Intel HD Graphics
> Try to enforce the full composition pipeline (nvidia-settings, will draw more
> energy)
>

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Thomas Lübking]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #128 from Thomas Lübking  ---
> Plasma freezes for a moment and then all advanced graphics appear frozen.
Sounds just as if steam blocks/disables the compositor?

> My wallpaper even reverts back to some previous datetime's image.
That I cannot explain at all.

> when opening any app while a video is playing underneath makes the video 
> stutter
This is either by the opening animation (crucial?) and the video running at
different FPS or (rather?) I/O related (in this case different "apps" will have
different impact)

> which doesn't open with an Intel HD Graphics
Try to enforce the full composition pipeline (nvidia-settings, will draw more
energy)

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Ryein Goddard]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #127 from Ryein Goddard  ---
Nvidia may not care specifically about KDE/Plasma to the extent you 
want, but saying it doesn't care is clearly wrong.  They do care about 
Linux.  In fact Nvidia knows its cards need to work well on Linux for ML 
and various other tasks.  I have over 100 steam games that work well on 
Linux and Nvidia has made fixes needed at times.


When I launch a game Plasma freezes for a moment and then all advanced 
graphics appear frozen.  My wallpaper even reverts back to some previous 
datetime's image.  Not saying this is for sure the KDE Communities' 
fault.  I am just saying we should clean up our own house before casting 
shade on another's.


I understand people getting pissed by things not working, but how you 
get things done is by providing paths for people to get involved and 
help.  If they disagree you don't just put your head in the sand, or 
give them the finger.  What you should do is talk about it and if Nvidia 
truly does something messed up let the community know, but be careful 
because the Linux zealots will be overly obtuse.


I am all for GNU/Linux, but I think we should all be pragmatic while 
sticking to our guns.


On 02/01/2018 05:29 AM, Twisted Lucidity wrote:
> https://bugs.kde.org/show_bug.cgi?id=322060
>
> --- Comment #126 from Twisted Lucidity  ---
> (In reply to Mahendra Tallur from comment #125)
>> I cannot believe [nvidia] are not at least a little concerned.
> I can well believe that nvidia are unconcerned, desktop GNU/Linux is going to
> be such a small share of their market that there probably isn't the profit in
> making things work and culturally nvidia appear to be hostile to F/OSS.
>
> The correct "fix" is probably to swicth to AMD/Intel, which will basically be
> mandated anyway as more distros switch to Wayland. Which kinda sucks for those
> of us on nvidia, but life happens.
>
> At the moment I find that keeping desktop effects enabled & using
> '__GL_YIELD="USLEEP"' makes the problems mostly go away.
>

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Twisted Lucidity]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #126 from Twisted Lucidity  ---
(In reply to Mahendra Tallur from comment #125)
> I cannot believe [nvidia] are not at least a little concerned.
I can well believe that nvidia are unconcerned, desktop GNU/Linux is going to
be such a small share of their market that there probably isn't the profit in
making things work and culturally nvidia appear to be hostile to F/OSS.

The correct "fix" is probably to swicth to AMD/Intel, which will basically be
mandated anyway as more distros switch to Wayland. Which kinda sucks for those
of us on nvidia, but life happens.

At the moment I find that keeping desktop effects enabled & using
'__GL_YIELD="USLEEP"' makes the problems mostly go away.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #125 from Mahendra Tallur  ---
@Martin Flöser : thanks, again for your replies, your work, as well as your
blog posts and technical decisions. This is most appreciated.

I will clearly stop bothering you about Nvidia. 

As a consumer, can anyone here tell me what is the state of the discussion with
Nvidia, what are they aware of ? Did some users here get in touch with them
through their forums or through their bugtracker, if any ? Any link so I could
add my data to existing reports ? 

I cannot believe they are not at least a little concerned. It's crazy that, for
instance, when opening any app while a video is playing underneath makes the
video stutter, which doesn't open with an Intel HD Graphics. Or that desktop
effects randomly stutter, etc.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Thomas Lübking]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #124 from Thomas Lübking  ---
Impossible. nvidia and nouveau are incompatible on the kernel layer and act on
the same HW. It's no way near the optimus condition.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Ryein Goddard]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #123 from Ryein Goddard  ---
It would be cool if we could dynamically load the nvidia binary 
driver(like nvidia prime but switching with the open and closed driver 
quickly) when ever we want so we can have the best of both worlds and 
not even worry about any of those things.  Screen tearing is probably 
the one thing I hate about KDE/Plasma right now compared with other 
solutions that for whatever reason do not have this issue.


On 01/14/2018 12:22 PM, Mahendra Tallur wrote:
> https://bugs.kde.org/show_bug.cgi?id=322060
>
> --- Comment #120 from Mahendra Tallur  ---
> Hi again,
>
> I would like to raise a different but likely connected issue :
>
> on my setup, either setting USLEEP or triple buffering does fix the tearing
> issue. With either, performance is wonderful in 3D games (1060 GTX + i3 CPU).
>
> However, what boggles me is the responsiveness and smoothness of kwin itself 
> (I
> mean the desktop : resizing windows, raising menus etc.) is inconsistent. The
> same animation can be butter smooth then the next time appears jerky. It's
> actually always happened as long as I can remember when using kwin and Nvidia
> cards.
>
> It seems slightly better with triple buffer, but as I don't want to add input
> lag in games...
>
> I kinda supposed it was a standard behaviour, but I noticed that even old
> machines with Intel HD Graphics would show a perfectly constant 60 FPS in 
> kwin.
> I tried to remove my Nvidia and use the built-in Intel HD and the desktop felt
> perfect. It even seemed to feel smoother with the Nouveau driver.
>
> I'm pretty sure all this is also related to the difficulty to work with the
> proprietary driver. As you devs are aware of the vsync issue, what's your
> opinion on the "desktop smoothness" issue ?
>
> Thanks again :-)
> Best regards & happy new year :)
>

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Thomas Lübking]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #122 from Thomas Lübking  ---
Comment #120 sounds more like a client related issue anyway - resizing
(QtQuick) GL contexts is PITA - at least on nvidia but OPenGL wasn't drafted
for this behavior anyway.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Martin Flöser]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #121 from Martin Flöser  ---

> As you devs are aware of the vsync issue, what's your
> opinion on the "desktop smoothness" issue ?
> 
Honestly, I stopped caring about nvidia specific problems years ago. To me
Nvidia stopped to matter the day I switched my developer systems to Wayland.
They run Intel as NVIDIA doesn't support gbm. Due to that even if I wanted to,
I would not be able to install an Nvidia card and test issues.

Nowadays my opinion is that it is the choice of the consumers to decide whether
they want nvidia with all that problems or not. They as consumers can bring
nvidia to fix issues, but not we devs. Every crash in the Nvidia driver gets
closer with please report to Nvidia. If all users do, it might change
something.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Shmerl]

https://bugs.kde.org/show_bug.cgi?id=322060

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #120 from Mahendra Tallur  ---
Hi again,

I would like to raise a different but likely connected issue :

on my setup, either setting USLEEP or triple buffering does fix the tearing
issue. With either, performance is wonderful in 3D games (1060 GTX + i3 CPU).

However, what boggles me is the responsiveness and smoothness of kwin itself (I
mean the desktop : resizing windows, raising menus etc.) is inconsistent. The
same animation can be butter smooth then the next time appears jerky. It's
actually always happened as long as I can remember when using kwin and Nvidia
cards. 

It seems slightly better with triple buffer, but as I don't want to add input
lag in games...

I kinda supposed it was a standard behaviour, but I noticed that even old
machines with Intel HD Graphics would show a perfectly constant 60 FPS in kwin.
I tried to remove my Nvidia and use the built-in Intel HD and the desktop felt
perfect. It even seemed to feel smoother with the Nouveau driver.

I'm pretty sure all this is also related to the difficulty to work with the
proprietary driver. As you devs are aware of the vsync issue, what's your
opinion on the "desktop smoothness" issue ?

Thanks again :-)
Best regards & happy new year :)

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=322060

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Thomas Lübking]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #119 from Thomas Lübking  ---
Given that thanks to QtQuick OpenGL is now everywhere, shipping a global
environment snippet might be a good idea.
Otherwise see the initial posts on problems to setup libgl from kwin this way.

I'd have to check over xmas whether the nvidia blob still exposes this
behavior.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #118 from Mahendra Tallur  ---
Hi Martin. Thanks a lot for the explanation. That's completely understandable.
Thanks again so much for your work !

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Martin Flöser]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #117 from Martin Flöser  ---
Maintainer speaking:

We will not add any workarounds! This has various reasons:

* We lack developers with the expertise to understand the problem
* We lack developers with NVIDIA cards
* The last patch we did for NVIDIA specific issue caused severe issues which
required an emergency release
* We have no chance to properly understand what's going on due to NVIDIA driver
being proprietary
* If the NVIDIA driver as thee only driver needs such workarounds, NVIDIA
should fix their drivers or contribute patches

Last but not least: X11 is going to be feature frozen after 5.12. We are almost
in feature freeze for 5.12 and given that we now have the Christmas break it's
unlikely that any feature for NVIDIA is going to land before. I don't see where
the devs should come from.

As NVIDIA does not support Wayland the feature freeze for X11 means that we
won't add any changes specific for NVIDIA any more.

I'm sorry for any inconvenience that creates for you. If you have any
complaints about it, please take it to NVIDIA to fix their driver or release it
as open source or to do anything which would allow us to not have to workaround
things.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Lastique]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #116 from Lastique  ---
"export __GL_YIELD=USLEEP" is not needed to prevent tearing if you're using
triple buffering (i.e. have it enabled in xorg.conf and define
KWIN_TRIPLE_BUFFER=1). However, that option can reduce CPU consumption
somewhat, so it's probably beneficial anyway. The problem is that __GL_*
variables are driver-specific and should preferably be defined somewhere global
(e.g. /etc/environment) so that all applications are affected, not just kwin.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #115 from Mahendra Tallur  ---
BTW, after re-reading myself I had the feeling my post sounded a little
strange, so I apologize if it sounded a little harsh, which was absolutely not
what I meant.

My point was just : in my experience (4 different PCs, about 6 different Nvidia
GPUs), this "export __GL_YIELD=USLEEP" workaround is always necessary to
prevent tearing. Also all my Nvidia + KDE using friends had to apply it as
well.

I know this is bad to apply a workaround systematically...  What other solution
do we have ? Is it up to the distros ?

Best regards

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Mahendra Tallur]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #114 from Mahendra Tallur  ---
Hi everyone ! Sorry for reducing the signal to noise ratio here :-)

I would like to ask the developers this question :

I know you are, for reasons I understand and respect, against all kinds of
"workarounds". 

However... This Nvidia + kwin tearing story has been around for ages. I mean,
5+ years is absolutely huge when it comes to software development. Power-users
can look for the solution but most average users won't and will be
disappointed. I witnessed this around me.

If we agree it's not a good thing to build-in a workaround for this specific
use case, what could be done ? Some kind or "ironic option" in KWin settings
explicitly referring to the bug it's working around (as I guess it's Nvidia's
fault to some extent) ? Or shouldn't at least distro providers do something
about it even if it's not built in Kwin ?

Sorry for my useless blabbering :-) and congrats again for all you've been
doing. I love Kwin & the KDE ecosystem :-)

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=322060

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[bugzilla_noreply]

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Ryein Goddard]

https://bugs.kde.org/show_bug.cgi?id=322060

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--- Comment #113 from Ryein Goddard  ---
This also effects me on 16.04 Kubuntu with backports ppa and the Nvidia Cuda
driver package compatible with Cuda 8.0

Adding export __GL_YIELD="USLEEP"
to /etc/profile.d/kwin.sh fixed the problem although I am sure this is probably
just a work around.

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Jesse]

https://bugs.kde.org/show_bug.cgi?id=322060

--- Comment #112 from Jesse  ---
My bug (382831) was marked as a duplicate of this bug, so I guess I'll throw my
two cents in, here. I read through this bug -- a lot of it pretty technical and
over my head. My issue with KwWin is screen-tearing while using Nvidia
proprietary drivers:

BEHAVIOR
When I enable the screen tearing prevention in the Compositor settings, click
apply, then drag & move a window around, screen tearing seems fixed for a few
seconds, but the tearing returns after that. Changing the settings again
produces the same result: tearing is fixed for a few seconds, but dragging and
moving a window across the screen will show that screen tearing returns.

EXPECTED BEHAVIOR
When tearing prevention is applied (regardless of the setting or the driver
used), the settings stick after you click APPLY or OK, and the tearing is gone.

ISSUE DISCOVERED WHILE USING
Kubuntu 17.04 x64
KDE Plasma 5.10.4 (via ppa:kubuntu-ppa/backports)
KDE Frameworks 5.36.0
Qt 5.7.1
Linux kernel 4.10.0-28-generic
Nvidia GTX 1080 graphics card
Nvidia 384.59 proprietary driver (via ppa:graphics-drivers/ppa)

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[bugzilla_noreply]

https://bugs.kde.org/show_bug.cgi?id=322060

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[Martin Flöser]

https://bugs.kde.org/show_bug.cgi?id=322060

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--- Comment #111 from Martin Flöser  ---
*** Bug 382831 has been marked as a duplicate of this bug. ***

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[kwin] [Bug 322060] Synced swapping on double buffered nvidia GPUs cause high CPU load

[via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=322060

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