Intel vs. Modesetting X.Org DDX Performance Impact

[andre30correia]

One more bad thing about modesetting is that it brings ugly diagonal tearing on Haswell. Happens with a non-compositing window manager, happens with Compiz 0.8 (which I have to use because of color management via compicc add-on), doesn't happen with Cinnamon's Muffin.

why you don't use compiz 0.9?

[Sloth]

Meh, intel is not just much faster in the 2d tests. it obliterates modesetting. Its like 100-1000x faster...

For OpenGL tests I'm surprised: I run KDE Plasma right now with kwin/qt using OpenGL for UI acceleration: it is noticeably faster with the intel driver vs the modesetting driver

Exactly my setup. I see a some "obliteration", but mostly modesetting as same speed or slightly slower/faster (this has changed a LOT, comparing what I see and what Michael sees, based either on the fact that I am bleeding edge on everything, or that I'm on Skylake and he's testing Haswell.)

From a sheer usability standpoint, it's impossible for me to tell the diff between the two, except for some weirdness with my IDE and Intel, which is off the charts annoying.

[Zan Lynx]

One more bad thing about modesetting is that it brings ugly diagonal tearing on Haswell. Happens with a non-compositing window manager, happens with Compiz 0.8 (which I have to use because of color management via compicc add-on), doesn't happen with Cinnamon's Muffin.

I think my laptop is using a Haswell chip (I can never remember the code names). I get that weird tearing with Firefox scrolling in a Wayland session too. Even though Wayland is running sync to screen blank, the update of the Firefox surface through XWayland isn't. Never happens with GTK3 apps.

It's an artifact of the memory block copies racing with the raster scan.

[smitty3268]

Exactly my setup. I see a some "obliteration", but mostly modesetting as same speed or slightly slower/faster (this has changed a LOT, comparing what I see and what Michael sees, based either on the fact that I am bleeding edge on everything, or that I'm on Skylake and he's testing Haswell.)

From a sheer usability standpoint, it's impossible for me to tell the diff between the two, except for some weirdness with my IDE and Intel, which is off the charts annoying.

I think it's likely that you're on Skylake.

SNA by it's nature is highly hardware specific, and has to be tuned extensively to run on hardware. By the time Skylake had come out, the intel driver was already seeing limited activity, and on top of that Skylake has more powerful 3D hardware to accelerate Glamor than the older generations as well.

[patrakov]

why you don't use compiz 0.9?

Because there is no compicc for Compiz 0.9, and because 0.8 is still maintained.

[greatquux]

I'm still using an old Sandybridge PC (!) so in my situation at least Wayland is noticeably slower for me. But the intel driver and Xorg aren't going away, they just may not become the default, and for new installs on newish hardware (probably >2014) I think it makes a lot of sense to use wayland+modesetting/glamor. The intel driver has gotten bugfixes since the last debian/ubuntu snapshot (20160706 I believe) in the repos, I had various instabilities using it until I checked it out and compiled it myself. As long as we can still use older tech for older hardware I think we'll all be fine.

[ypnos]

I have a desktop Skylake chip and can confirm, modesetting runs very smooth and has less/no bugs than the intel driver. Is also better with tearing. Basically, tearing problems in video just disappeared with the switch to modesetting.

It is quite obvious that the hardware is key factor in preference of modesetting or intel. Therefore I hope they continue to maintain their SNA driver for anybody on older platforms, including my laptop.

[andrei_me]

I got an Ivybrigde notebook, using Gnome 3, if I change to modesetting it is utterly slow, barely usable.

[akostadinov]

With the modesetting driver I had frequent short monitor disconnects and freezes. Forced "Intel" driver since 2 years. Not sure if things are fixed by now.

[Zan Lynx]

With the modesetting driver I had frequent short monitor disconnects and freezes. Forced "Intel" driver since 2 years. Not sure if things are fixed by now.

Kind of funny to comment on a 4 year old article.

Anyway.

If modeset doesn't work for you with Intel graphics then it isn't the driver. It's your low quality cable. Because modeset only tries the connection once or twice while the other driver tries it repeatedly.

Some time in 2016 I think, I had a defective mini-DP cable that did that with 60 Hz 4K DisplayPort. Replaced the cable with a modern one and never had a problem with modeset again.

I recently argued with someone who kept claiming that his 10 year old HDMI cable was just fine and his new TV was defective. He would rather be "right" than buy a new, HDMI 2.1 cable. Whatever. I hope you aren't the same.