Unity is unusuably slow with fallback software rendering (LLVMpipe)

Status changed to 'Confirmed' because the bug affects multiple users.

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1046497, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.

I'm re-opening this as recommended in https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1046497/comments/14 is there further information that would be helpful at this point?

Just to confirm after reopening... What Unity version are you on now? You can check by running:
    dpkg -l unity

I'm on 6.8.0, should I be expecting a fix in 7.0.0?

I've set the milestone to 7.0 (Ubuntu 13.04) but that does not guarantee a fix. It just makes the problem more visible to the team.

This is a major issue: "unusable" is by no means an exaggeration: I can literally watch the different shades of a fade-out/in effects painting from top to down of every window on my Intel T9400 in Virtual Box.

I made the same observation as benbuntu on VirtualBox on a Lenovo X220 (Core i7 2640M @ 2.8 GHz, 12 GB). As windows fade in/out the progress is so slow you see every step in the fading process.

Having previously used Ubuntu 8.04 I later moved to Xubuntu 9.10 and currently Lubuntu 11.10. So I'm not really familiar with how the Unity experience has evolved over the past few releases. This comment is mostly about my first impressions on booting the Ubuntu 12.10 x86 CD in a VirtualBox VM.

The user experience is, to be frank, awful. It's almost unusably slow.

No accelerated graphics driver is loaded when the CD boots. The overall GUI experience is dog-slow, and that's with a ~2GHz Core 2 Duo. I imagine many potential users will try Ubuntu/Unity and be put off before even installing it. Not to mention users of ARM systems which have significantly slower CPUs and probably no accelerated graphics driver available even after installing...

13.04 is supposed to have an emphasis on efficiency, so I hope something can be done about the unaccelerated graphics experience by then. Probably many systems are unaccelerated when booting the CD, even if an accelerated driver might be available after installation. It gives a very poor impression to potential users.

I recently read about Enlightenment, and how it's supposed to be very efficient even with various "blingy" graphical effects. So I downloaded an Ubuntu-based distribution which uses it, Bodhi Linux (http://sourceforge.net/projects/bodhilinux/).

I booted the Bodhi CD in VirtualBox and selected the Compositing profile. Once the desktop had loaded, there was a stark contrast between the fluidity of the GUI vs Ubuntu/Unity. Try opening several windows and Alt-Tabbing between them. Even with my system slowed to 800MHz that was pretty smooth.

Is there any possibility for a future version of Unity to build on or borrow ideas/code from Enlightenment? That could largely solve the problem. (Apparently Enlightenment does use accelerated graphics when available.)

The reason why llvmpipe is slow is because it is a completely software-based rendering solution, the whole desktop is rendered in software and then pushed at once. A change of a single pixel is causing full desktop redraw on every frame. I have filed LP:1098744 to track disabling the animations in case low graphics mode is enabled which will make it a bit faster but not fast enough to be considered useful in these environments.

I have also tested Intel HD 3000 running under plain VESA driver on Core i5 @ 2.5GHz and surprisingly found the performance of llvmpipe-based Unity to be quite on par with the accelerated version so it appears that some systems are indeed OK with such kind of full screen redraw mode.

Roman,

Software-based rendering can be quite fast. And the way Compiz renders the screen is using buffer swapping (in 0.9.8 and later) which is implemented efficiently in most cases using page flipping. Page flipping is efficient even without hardware rendering.

(Showing my age) I remember when we used to render everything in software on 16MHz CPUs. It's possible for software-based rendering to be fast (although less common these days).

However the main problem in this bug is the slow(er) software-based implementation of shaders in LLVMpipe, which Nux (and hence Unity) relies on heavily. So it is a problem specific to Unity, not Compiz.

When using mesa 9.2-devel git from 12th April 2013 (specifically up to and including commit c6a86fb5639977f37a1403012669cdee86bbd89f (r300g: Fix bug in OMOD optimization)), LLVMpipe is significantly faster than it was on mesa 9.1.1. See http://www.phoronix.com/scan.php?page=article&item=mesa_92dev_llvmpipe for some examples.

The xorg-edgers PPA at https://launchpad.net/~xorg-edgers/+archive/ppa currently has a mesa build from 4th April 2013 git. This will likely be updated soon.

Is this still occurring in Ubuntu 14.04 "Trusty Tahr"?

I just tried the current daily built in a VirtualBox on a fast T4200 (software rendering) as well as natively (RS880 Gallium rendering) on an Neo K350 Lenovo Edge 11 [Mobility Radeon HD 4250].

Speed improvement is indeed drastic, so 'unusable' is no longer appropriate. Though 'making fun to use', neither.

Opening dashboard takes ~2-3s under VirtualBox, 1-2s as native 3D on the Edge. Under Unity2D opending the dash occurs instantly including blur effect on both environments. At least one interims shade grade is still visible on trsuty. Also other desktop operations like window maximizing are visibly laggy (~0.6s).

I recently tried the Ubuntu Gnome Alpha Build on the Edge, which I remember quite snappy w/o significant lags while toying around.

Based on my user experience I would say it's "ok" now, but still a bit annoying for daily use on low powered devices and VMs. Maybe turning off some visual goodies in those environment could help to close that final gap.

Based on comment #15, I'm going to close this Fix Released since it's no long unusable. I agree that running Compiz/Unity on llvmpipe is not fun and miss Unity 2d for these types of systems.