** Also affects: nvidia-graphics-drivers-550 (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2052597
Title:
NVreg_PreserveVideoMemoryAllocations=1 should be the default
Status in nvidia-graphics-drivers-535 package in Ubuntu:
New
Status in nvidia-graphics-drivers-550 package in Ubuntu:
New
Bug description:
As far as I can tell, any system with an NVIDIA graphics card won't
resume from sleep correctly when running mantic unless the NVIDIA
driver has the option `NVreg_PreserveVideoMemoryAllocations=1` set.
This is because by default most video memory allocations are not
preserved on suspend and the user space needs to handle the case where
(from the application's point of view) they suddenly and mysteriously
go missing.
The GNOME shell fails to do this and fails fairly spectacularly. This
results in a wide variety of visual defects but leaves the system
unusable.
The suggested option works around this by making the driver write
video memory out to file while suspending and restoring video memory
from file when resuming. It's important that the path where this
temporary file is written out has enough free space to hold all of
video memory; on mantic, `/tmp` (the default) seems appropriate as it
is not a ramfs but this could be configured elsewhere.
While there are obviously cases where this behaviour is not desired
(mainly where GPUs are used for non-display purposes), it seems likely
that in the vast majority of cases where such a GPU is present and the
system is regularly put into a sleep state that the GPU will be used
for display and not as a GPGPU. Systems that are put into sleep
states tend to be portables, where the GPU is primarily for display;
systems used for GPGPU tend not to be portable and are not usually put
into sleep states where the GPU is shut down. Obviously these are
generalisations, but they are _generally_ true. It's also likely that
users doing GPGPU will already have to go and reconfigure their
systems for optimal performance whereas desktop users generally expect
the system to work correctly out of the box. I'm a long-term Ubuntu
user and software engineer and it took me a couple of weeks to figure
out that suspend isn't broken on my new laptop, I just need to set GPU
driver options; the chances of a normal user figuring this out are
slim.
I'd suggest that putting the option in /etc/modprobe.d/nvidia-
graphics-drivers-kms.conf is likely to be the right way to achieve
this.
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 23.10
Release: 23.10
Codename: mantic
$ apt-cache policy nvidia-kernel-common-535
nvidia-kernel-common-535:
Installed: 535.154.05-0ubuntu0.23.10.1
Candidate: 535.154.05-0ubuntu0.23.10.1
Version table:
*** 535.154.05-0ubuntu0.23.10.1 500
500 http://gb.archive.ubuntu.com/ubuntu mantic-updates/restricted
amd64 Packages
500 http://security.ubuntu.com/ubuntu mantic-security/restricted
amd64 Packages
100 /var/lib/dpkg/status
535.113.01-0ubuntu3 500
500 http://gb.archive.ubuntu.com/ubuntu mantic/rest
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