Virtual guests' console is unusably slow due to framebuffer usage

Bug #582145 reported by Andreas Ntaflos on 2010-05-18
114
This bug affects 20 people
Affects Status Importance Assigned to Milestone
linux (Ubuntu)
Medium
Unassigned

Bug Description

This was also discussed in https://lists.ubuntu.com/archives/ubuntu-server/2010-May/004172.html

The problem is that the console of a Ubuntu 10.04 (server) virtual machine/guest becomes incredibly slow and really unusable as soon as it starts scrolling. This is apparently due to the kernel switching on the console framebuffer which does not play well with the VNC-based console viewers of virt-manager. I have created a screencast to demonstrate, please find it here: https://daff.pseudoterminal.org/misc/console-slow.ogg

I have experienced this using KVM and virt-manager/virt-viewer on Ubuntu 10.04 and Ubuntu 9.10 hosts (using the server edition, FWIW). Apparently it also happens with VirtualBox but I have not tested this myself. The only solution for the time being seems to be to blacklist the vga16fb module as suggested by Paul Nuffer:

    $ echo "blacklist vga16fb" | sudo tee -a /etc/modprobe.d/blacklist

Merely adding "nomodeset" to the kernel boot options is not sufficient.

I don't even know exactly to which package this bug belongs let alone what to do about it except force the kernel not to use a console framebuffer. I know Plymouth needs the framebuffer to display splash screens and whatnot but there should be a proper way to disable it when running as a virtual machine. And since the splash screen is disabled anyway when creating a server virtual machine there is really no use in a framebuffer, especially if it slows everything down to a crawl. So what to do?

Shef (shafeev) wrote :

Hello, try to add in /etc/modprobe.d/aliases

alias vesafb off
alias vga16fb off
alias vgastate off
alias softcursor off
alias cfbimgblt off
alias cfbfillrect off
alias cfbcopyarea off
alias fbcon off
alias tileblit off
alias font off
alias bitblit off

then dpkg-reconfigure linux-image-`uname -r`
now I have super spedd console in VM

Brian Candler (b-candler) wrote :

Under Lucid I notice there is /etc/modprobe.d/blacklist-framebuffer.conf already, but it doesn't blacklist vga16fb. Adding that was the solution for me, although the font now isn't quite as pretty.

affects: ubuntu → linux (Ubuntu)
Jeremy Foshee (jeremyfoshee) wrote :

Hi Andreas,

This bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? Can you try with the latest development release of Ubuntu? ISO CD images are available from http://cdimage.ubuntu.com/releases/ .

If it remains an issue, could you run the following command from a Terminal (Applications->Accessories->Terminal). It will automatically gather and attach updated debug information to this report.

apport-collect -p linux 582145

Also, if you could test the latest upstream kernel available that would be great. It will allow additional upstream developers to examine the issue. Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Once you've tested the upstream kernel, please remove the 'needs-upstream-testing' tag. This can be done by clicking on the yellow pencil icon next to the tag located at the bottom of the bug description and deleting the 'needs-upstream-testing' text. Please let us know your results.

Thanks in advance.

    [This is an automated message. Apologies if it has reached you inappropriately; please just reply to this message indicating so.]

tags: added: needs-kernel-logs
tags: added: needs-upstream-testing
tags: added: kj-triage
Changed in linux (Ubuntu):
status: New → Incomplete
Launchpad Janitor (janitor) wrote :

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]

Changed in linux (Ubuntu):
status: Incomplete → Expired

AlsaDevices: Error: command ['ls', '-l', '/dev/snd/'] failed with exit code 2: ls: cannot access /dev/snd/: No such file or directory
AplayDevices: Error: [Errno 2] No such file or directory
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory
CurrentDmesg:
 [ 12.442588] eth0: no IPv6 routers present
 [ 83.473875] hrtimer: interrupt took 3368866 ns
DistroRelease: Ubuntu 10.04
InstallationMedia: Ubuntu-Server 10.04 LTS "Lucid Lynx" - Release amd64 (20100427)
Lsusb: Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: Bochs Bochs
Package: linux (not installed)
PciMultimedia:

ProcCmdLine: BOOT_IMAGE=/vmlinuz-2.6.32-31-server root=/dev/mapper/hostname-root ro
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 LC_MESSAGES=en_US.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.32-31.61-server 2.6.32.32+drm33.14
Regression: No
Reproducible: Yes
Tags: lucid graphics needs-upstream-testing
Uname: Linux 2.6.32-31-server x86_64
UserGroups:

dmi.bios.date: 01/01/2007
dmi.bios.vendor: Bochs
dmi.bios.version: Bochs
dmi.chassis.type: 1
dmi.chassis.vendor: Bochs
dmi.modalias: dmi:bvnBochs:bvrBochs:bd01/01/2007:svnBochs:pnBochs:pvr:cvnBochs:ct1:cvr:
dmi.product.name: Bochs
dmi.sys.vendor: Bochs

Changed in linux (Ubuntu):
status: Expired → Confirmed
tags: added: apport-collected

apport information

Tyler (tyler-atws) wrote : Lspci.txt

apport information

apport information

apport information

apport information

apport information

apport information

Tyler (tyler-atws) wrote :

- VM Host:
# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 10.04.2 LTS
Release: 10.04
Codename: lucid
# uname -a
Linux virtua1 2.6.32-31-server #61-Ubuntu SMP Fri Apr 8 19:44:42 UTC 2011 x86_64 GNU/Linux

- VM Guest:
# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 10.04.2 LTS
Release: 10.04
Codename: lucid
# uname -a
Linux virtualguest 2.6.32-31-server #61-Ubuntu SMP Fri Apr 8 19:44:42 UTC 2011 x86_64 GNU/Linux
# relevant /etc/default/grub settings
GRUB_GFXMODE=800x600x15 (does the same thing with 640x480 (default))
GRUB_GFXPAYLOAD_LINUX=KEEP
# relevant KVM info:
video card: set to cirrus 9mb (default I think?)
virtual display: vnc server
console device 0 (primary console)
- device type: pty
- source path: /dev/pts/3

I have not tried any of the blacklisting as mentioned by others in the first few comments of this bug report

Tyler (tyler-atws) wrote :

I'm using Virt-Manager on an Ubuntu 10.04 LTS x64 machine with GUI

From Help -> About in virt-manager
Virtual Machine Manager 0.8.2

Mark - Syminet (mark-syminet) wrote :

Same problem here. Workaround was to add the following line to /etc/modprobe.d/blacklist.conf:

blacklist vga16fb

reboot, and vnc works as it should.

Mark - Syminet (mark-syminet) wrote :

sorry, that should be add this line to /etc/modprobe.d/blacklist-framebuffer.conf :

blacklist vga16fb

...superfast VM console now.

meejah (meejah) wrote :

I confirm this on a fresh (via VMBuilder) 10.04 LTS install. The scrolling problem exists in both VNC and default kvm mode (SDL).

The above blacklist workaround fixes my problem (note that the blacklisting is in the guest, not host).

tags: added: karmic lucid

Andreas Ntaflos, thank you for taking the time to report this bug and helping to make Ubuntu better. Please execute the following command, as it will automatically gather debugging information, in a terminal:
apport-collect 582145
When reporting bugs in the future please use apport by using 'ubuntu-bug' and the name of the package affected. You can learn more about this functionality at https://wiki.ubuntu.com/ReportingBugs.

As well, could you please test the latest upstream kernel available following https://wiki.ubuntu.com/KernelMainlineBuilds ? It will allow additional upstream developers to examine the issue. Please do not test the daily folder, but the one all the way at the bottom. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this bug is fixed in the mainline kernel, please add the following tags:
kernel-fixed-upstream
kernel-fixed-upstream-VERSION-NUMBER

where VERSION-NUMBER is the version number of the kernel you tested. For example:
kernel-fixed-upstream-v3.11-rc5

This can be done by clicking on the yellow circle with a black pencil icon next to the word Tags located at the bottom of the bug description. As well, please remove the tag:
needs-upstream-testing

If the mainline kernel does not fix this bug, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-VERSION-NUMBER

As well, please remove the tag:
needs-upstream-testing

If you are unable to test the mainline kernel, please comment as to why specifically you were unable to test it and add the following tags:
kernel-unable-to-test-upstream
kernel-unable-to-test-upstream-VERSION-NUMBER

Once testing of the upstream kernel is complete, please mark this bug's Status as Confirmed. Please let us know your results. Thank you for your understanding.

Changed in linux (Ubuntu):
importance: Undecided → Medium
status: Confirmed → Incomplete
Maarten Bezemer (veger) wrote :

On my search to a solution of slow scrolling in my terminals (tty) I stumbled upon this report.

After upgrading from 3.12.4 to 3.13-rc7 the problem is gone (without blacklisting additional fb modules).

Note: I'll leave the tags are report status for the Andreas

Maarten Bezemer, thank you for your comment. So your hardware and problem may be tracked, could you please file a new report with Ubuntu by executing the following in a terminal while booted into a Ubuntu repository kernel (not a mainline one) via:
ubuntu-bug linux

For more on this, please read the official Ubuntu documentation:
Ubuntu Bug Control and Ubuntu Bug Squad: https://wiki.ubuntu.com/Bugs/BestPractices#X.2BAC8-Reporting.Focus_on_One_Issue
Ubuntu Kernel Team: https://wiki.ubuntu.com/KernelTeam/KernelTeamBugPolicies#Filing_Kernel_Bug_reports
Ubuntu Community: https://help.ubuntu.com/community/ReportingBugs#Bug_reporting_etiquette

When opening up the new report, please feel free to subscribe me to it.

Thank you for your understanding.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs

Maarten Bezemer (veger) wrote :

The newest mainline kernel (for saucy) 3.11.0-15 does not show the problem... So I guess it does not make sense to open a new report?

Launchpad Janitor (janitor) wrote :

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]

Changed in linux (Ubuntu):
status: Incomplete → Expired
datube (datube) wrote :

Hi,

We recently also experiencing this issue on Ubuntu 12.04. I've tried the suggestions stated in comment:1. This didn't gave any relief. To get back to the "console speed" I was used to in Lucid, I did the following:
- downloaded the following files: libgtk-vnc-1.0-0_0.3.10-2ubuntu2.2_i386.deb & python-gtk-vnc_0.3.10-2ubuntu2.2_i386.deb
- from python-gtk-vnc: boldy copied /usr/lib/python2.6/dist-packages/gtkvnc.so over /usr/lib/python2.7/dist-packages/gtkvnc.so
- downgraded libgtk-vnc: dpkg -i --force-all libgtk-vnc-1.0-0_0.3.10-2ubuntu2.2_i386.deb

After that I gained back the usability for virt-manager and I'm able to watch htop (for examle) as I expected. Maybe this helps.

datube, thank you for your comment. So your hardware and problem may be tracked, could you please file a new report with Ubuntu by executing the following in a terminal while booted into a Ubuntu repository kernel (not a mainline one) via:
ubuntu-bug linux

For more on this, please read the official Ubuntu documentation:
Ubuntu Bug Control and Ubuntu Bug Squad: https://wiki.ubuntu.com/Bugs/BestPractices#X.2BAC8-Reporting.Focus_on_One_Issue
Ubuntu Kernel Team: https://wiki.ubuntu.com/KernelTeam/KernelTeamBugPolicies#Filing_Kernel_Bug_reports
Ubuntu Community: https://help.ubuntu.com/community/ReportingBugs#Bug_reporting_etiquette

When opening up the new report, please feel free to subscribe me to it.

Thank you for your understanding.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs

Alan Lord (theopensourcerer) wrote :

Still a big issue.

We run a 14.04 Host on the bare-metal, with 14.04 guests. From my remote Ubuntu 15.04 desktop the virt-manager windows are pretty useless.

Have tried various combinations of spice and VNC and graphics options in the virt-manager guest configuration but it seems to make little or no difference.

Alan Lord, it will help immensely if you filed a new report via a terminal:
ubuntu-bug linux

Please feel free to subscribe me to it.

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