Cause of slow graphics?

[BrimestoneMilky]

Hi.

I have ran into the same graphics issue that was raised in this post:

Screen updates very slowly and erroneously in several but not all applications

I have had Lubuntu 20.04 for some time. Today I suddenly got problems when the screen started updating very slowly and erroneously in several but not all applications. I tried to take a screenshot of this behaviour but it turned out to be impossible to capture on screenshots. However I took a picture from my mobile phone (enclosed) that shows how the problem looks like. The screen still updates correctly in some apps, such as Google Chrome, so that makes me think that there is nothing wrong with…

From the post it seems the issue was solved but do anybody know why the issue occurred?

I have two Lubuntu 20.04 machines (for redundancy), where I very rarely run updates or install applications. Therefore I am 99.99% sure that this issue was not introduced with an update or install of an application. The issue first occure on one machine (that I use daily) from one day to the other with no updates or installs having been performed. Then I started working on my redundant second machine while I figured out what was going on with machine one. But now after a two days of working on my second machine the issue appeared here as well, also without performing any updates or installs?

I was just wondering if anybody know how such an issue can occure on systems where no new changes have been applied? Are there background updates of drivers that occure even though you are not performing automatic or manual updates on your own?

Thanks for all the great work people are putting into Lubuntu, I am truly greatful for these efforts.

Best regards

Edit: I just realized that I have “Install security updates without confirmation” enabled. So the issue can obviously have been introduced through these updates, my apologies.

Would still be interesting to hear if anybody have figured out if this was how the issue were introduced?

[BrimestoneMilky]

I have now created yet another installation of Lubuntu 20.04 without getting the latest updates. This machine has all updates disabled and has now been running for a week without the graphics issue (from the linked post) occuring.

However I can probably not make security updates without the graphics issue being introduced which is kind of a problem. I can probably install some drivers like in the linked post but having to get drivers for something that used to work is also not optimale.

Has there been any solutions to this graphics issue that does not need installation of additional drivers? From my little experiment with different Lubuntu installations it seems like the issue must have been introduced through security updates.

Best regards

[guiverc]

Which kernel stack are you using?

Ubuntu LTS releases have two main kernel stack choices; GA & HWE (with some OEM options available as well for specific detected hardware though Lubuntu media doesn’t include this by default). With Lubuntu the media used to install your system controls which kernel stack you’re using.

You can refer to Kernel/LTSEnablementStack - Ubuntu Wiki for more details, but with Lubuntu, 20.04 installs will use the GA stack if 20.04 or 20.04.1 media is installed; but HWE is default if 20.04.2 or later media is used for the installation. I wonder if by security updates you’re just talking about the HWE kernel upgrading (but you weren’t specific) as if it’s that, installing with GA default media; OR switching to GA kernel stack before you upgrade may avoid the issue.

What kernel were you using when it worked? and what kernel was being used when you had troubles?

Without specifics, we’d only be guessing as to cause & thus fix.

[BrimestoneMilky]

I’m really not very experienced with Lubuntu/Linux so bare with me
Google told me to type in this command “lsb_release -a” to see my version of Lubuntu.

Output:

No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.3 LTS
Release: 20.04
Codename: focal

So I guess my kernel stack is HWE.

By “Install security updates without confirmation” I mean having Software sources configured as in the below screens.

Best regards

[guiverc]

Sorry, I probably should have provided the

uname -r

command to display kernel details.

If you’re using 20.04.3 and using the GA kernel stack, you’ll be using the 5.4 kernel (just as you were at release time, GA keeps you on the same kernel for the life of the product, thus it’s default for all server installs - the most stable, and default for Lubuntu 20.04 & 20.04.1 installs).

If you’re using 20.04.3 and using the HWE kernel stack, you’ll be using the now EOL 5.11 kernel (though for a time as 20.04.4 changes rolled out to users, systems would report 20.04.3 but have already switched to the 20.04.4 5.13 kernel stack). The HWE stack is default for any installs of Lubuntu 20.04.2 or later media (ie. 20.04.3, 20.04.4, & 20.04.5 when released)

I’d suggest you apply security fixes to your system, as a fully upgraded & secure 20.04 system will report itself as 20.04.4 and not as yours has. This announcement shows the ISO release date, but that was a ~week later than installed systems upgraded.

[BrimestoneMilky]

I wasn’t being clear in my last post. Machines with the graphics issue:

Ubuntu 20.04.01 LTS (5.4.0-104-generic)

Ubuntu 20.04.04 LTS (5.4.0-104-generic)

both machines are auto updating the mentioned important security updates and the issue occurred almost exactly at the same time on both machines.

Machines without the issue:

Ubuntu 20.04.03 LTS (5.11.0-27-generic) this machine has all updates disabled now.

Ubuntu 20.04.03 LTS (5.13.0-37-generic) just to test I have just installed this machine and updated software (again with the mentioned software settings). The problem doesn’t seem to occure but I have only booted the machine twice.

[guiverc]

It looks like you’re having issues with the GA kernel stack (5.4), why not switch it to the HWE stack as you aren’t having issues as I understand it with the current 5.13 kernel (5.11 is unsupported as it was the stack from 21.04 which should have upgraded to 5.13 from 21.10 on a HWE focal system).

You can have both HWE & GA stacks installed, you select which you’ll use at boot time (ie. selecting at grub), though some closed-source kernel modules (eg. video drivers) do prevent both HWE & GA co-existing but you’ll have no issues if only open-source kernel modules (drivers) are installed/used.

It could be I’m missing something; the 5.11 is held back as that box has issues if upgraded?? If that’s the case; I’d not be exploring the issue as relating to Lubuntu, but related to the linux kernel & kernel module (driver) in use. I tend to use sudo lshw -C display to work out which kernel module/driver is being used (list hardware of class display; I find it easy to remember/explain), which I’d then use to look to see if others are experiencing it via bug reports on launchpad.net. If they are, I’d hope to find work arounds or fixes there, I’d click the “affects me too” if you find that perfectly matches, or just file a new bug report.

I’d also likely explore one of those systems using live media, ie. does the issue occur if you use a jammy daily? As jammy is about to enter beta, it’s the perfect time for bug reports to get noticed & get attention of the Ubuntu developers. Fixes may take awhile to get back to focal (ie. will likely get there at 20.04.5 & 5.15 kernel), but you may also get clues/details that will help with your older kernels too.

Sorry I can’t think of anything else currently; and I’ve gotta go too.

[BrimestoneMilky]

Seems correct that the issue is with the kernel version. I would really like to avoid doing any special setup with kernels or graphics drivers and just use whatever setup is automatically used when installing. Both because the work I do on the machines should not need any special setup and also I lag the skills

So I always just kept out of the box settings more or less. What was a little troublesome to me was that even though you only do important security updates that you risk introducing an issue that made my machines almost unworkable in my case (i.e. the machine worked but the UI experience became a disaster). But I guess this will always be the case with any upgrades. But I just wonder why some of my machines were “stuck” on the 5.4 version of the kernel when others were not… must have done something different on the stuck machines in the installation process even though I am quite meticulous with this process being the same on all machines.

Yes the 5.11 machine I just didn’t dare to update because I need at least one working machine at all time basically. But it seems I probably can update it without having issues as it is not stuck on 5.4. So I guess my solution will just be to reinstall machines again and making sure they are not on 5.4 kernel.

Anyways thank you very much for your time.

[guiverc]

@BrimestoneMilky

But I just wonder why some of my machines were “stuck” on the 5.4 version of the kernel when others were not… must have done something different on the stuck machines in the installation process even though I am quite meticulous with this process being the same on all machines.

If Lubuntu 20.04 LTS or Lubuntu 20.04.1 LTS media is used for an installation, the GA kernel (5.4) is used as the default kernel stack. This is the same as all prior Ubuntu releases (ie. 18.04, 16.04, 14.04, 12.04 etc.)

If Lubuntu 20.04.2 LTS or later media (ie. 20.04.2, 20.04.3, 20.04.4, 20.04.5 ISOs) are used for an installation, the HWE kernel is used by default, just like all other flavors of Ubuntu, and prior releases (ie. 18.04, 16.04, 14.04, 12.04 etc).

ie. with Lubuntu (and flavors) the media (ISO) used to install the system sets the default kernel stack.

Any system on which you used 20.04 or 20.04.1 media will remain on the GA or 5.4 kernel for the life of the product. Any system on which you used 20.04.2 or later media will instead use the HWE stack, ie. it used the 5.8 kernel at 20.04.2, 5.11 at 20.04.3, 5.13 at 20.04.4, and 5.15 when it reaches 20.04.5 which is the final HWE kernel and what it will remain on the remaining life of the product.

FYI: The kernel stack rolls out to machines before the version number incremented, ie. 20.04 systems were using the 5.13 kernel before the 20.04.3 changed to 20.04.4. The .3 to .4 change reflects all of the stack/upgrades for that change being installed, so occurs last with the changes rolling out a couple of weeks of upgrades.

Ubuntu 20.04 LTS Desktop ISOs differ to prior releases (ie. 18.04, 16.04 etc) in that started with 20.04, the HWE kernel stack was default for all installs regardless of media used. Ubuntu 20.04 LTS Server installs default to using the GA kernel stack, though as already stated in a prior comment; this can be changed during installation with the subiquity installer.

Details of this should be found in the wiki page I provided in my first reply (or in another page which is found on that wiki page). Lubuntu differs to the Ubuntu 20.04 LTS Desktop default the wiki is really explaining (as all flavors of Ubuntu do), as it follows the standards used by prior releases (ie. 18.04, 16.04, 14.04, 12.04 which is found in that page). Lubuntu media also won’t install OEM kernel stack(s) that Ubuntu Desktop can do (they aren’t on our ISOs).

With server installs - it’s assumed the most stable kernel is wanted - thus GA kernel is used.

With desktop installs; Ubuntu Desktop starting with 20.04 has opted to use the later kernel stack as it provides newer kernel modules (ie. drivers) useful on the latest hardware - ie. desktop users are expected to have newer hardware; server users prize stability. Regardless of media used, the wiki pages allow you to change that default; and if you’re using open-source drivers, you can have both stacks installed & as I’ve stated before, select which you want to use at boot time using grub.

I’ve tried to explain this before, hopefully clearer this time.

[BrimestoneMilky]

Hi.

It makes sense. I think I might have used different install mediums for some of the machines even though I tried not to :-/

Thx again for all the information.