[Bug 1069498]

[bwat47]

(In reply to comment #98)
> (In reply to comment #97)
> > Does anyone know if a fix for this (for intel cards) ever make it into kde
> > 4.9.x?
> 
> Actually the intel IGPs should operate on the glXCopySubBuffer path and that
> should not cause tearing but with some broken MESA versions.
> 
> The pending patch at https://git.reviewboard.kde.org/r/107198/ will
> *hopefully* still make it into 4.10 - it's however a far too massive change
> for a bugfix release (ie. 4.9) sorry.

I'm on ivybridge and I had tried kubuntu 12.10 which has pretty recent
mesa/kernel/driver versions (9.0, 3.5, 2.20.9).

AFIAK the problem is that currently sandybridge and ivybridge hardware
simply cannot get fully tear free output unless the compositor *always*
pageflips (ubuntu has changed compiz to behave this way by default in
ubuntu 12.10 and I get absolutely no tearing anywhere there). I can also
achieve totally tear-free output in gnome-shell by adding CLUTTER_PAINT
=disable-clipped-redraws:disable-culling to /etc/environment.

Intel is working on adding "legacy" vsync in kernel 3.8 afiak, but if
this is used it will cause significantly more power usage, since it
keeps the intel card out of its power saving state, so the proper way on
intel will still be to only use page-flipping, which is why that pending
patch you linked is probably the only thing that will gives
sandybridge/ivybridge users totally tear-free output.

It is possible to get tear-free fullscreen video currently if you use
unredirect fullscreen windows in kwin + opengl output in the video
player, but even that doesn't always work (it depends on the
application, some video players don't seem to page-flip even with opengl
output, for example see this vlc bug:
https://trac.videolan.org/vlc/ticket/7702

the best tear free video experience for ivybridge is to use an always
page-flipping compositor, with unredirect fullscreen windows disabled,
this seems to get rid of any and all tearing.

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https://bugs.launchpad.net/bugs/1069498

Title:
  KWin shows tearing despite of VSync

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