[Mooted] Kernel Rollback as part of 'nvidia' Rollback (folding@home)

grubenm · 2014-02-25 01:04:48

Hey all,

Currently running x86_64 arch linux 3.13.4-1, foldingathome 7.3.6-1, nvidia 331.38-3, nvidia-utils 331.38-3, and nvidia-libgl 331.38-3.

For foldingathome, I have two EVGA GTX 660s.

Unfortunately, the Folding@Home forums suggests that, in terms of foldingathome performance, nvidia 331.38-3 is far inferior to nvidia 325.15-11, so I'd like to rollback to 325.15-11 if possible.

'downgrade' tells me that 'nvidia' depends on 'nvidia-utils' and 'linux' which also need to be downgraded.

warning: downgrading package nvidia (331.38-3 => 325.15-11)
resolving dependencies...
warning: cannot resolve "linux<3.13", a dependency of "nvidia"
warning: cannot resolve "nvidia-utils=325.15", a dependency of "nvidia"
:: The following package cannot be upgraded due to unresolvable dependencies:
      nvidia

Checking the ArchWiki for instructions on rolling back 'nvidia', I discern only that 'nvidia-libgl' seems to also be an important package in this process, and that it should probably be downgraded as well:

Order of install/deinstall for changing drivers
Where the old driver is nvidiaO and the new driver is nvidiaN.
remove nvidiaO
install nvidia-libglN
install nvidiaN
install lib32-nvidia-libgl-N (if required)

Before I start hacking away at my kernel, I'd like to share the process I'm thinking of following and I welcome any comments and feedback which more experienced Arch Linux users may have:

(1) sudo systemctl disable foldingathome.service && sudo systemctl stop foldingathome.service
(2) sudo pacman -Rdds nvidia nvidia-utils nvidia-libgl
(3) sudo pacman -S nouveau (to allow for tty display after reboot) && reboot
(4) downgrade linux (something less than .13) && reboot
(5) sudo pacman -Rdds nouveau (since no longer needed)
(6) downgrade nvidia nvidia-utils nvidia-libgl (325) && reboot
(7) sudo systemctl start foldingathome.service (after which, check to see if coherent /opt/fah/log.txt output)
(8) (After 25 minutes, will want to check f@hweb or what have you for PPD estimate, which should be higher or this downgrade will have accomplished nothing)

As a fairly vanilla Arch Linux user, I'm admitted paranoid about breaking my system. As a complete ArchBBS newbie, I apologize in advance for the several forum posting rules I'm sure to have broken.

Last edited by grubenm (2014-02-26 04:07:56)

ewaller · 2014-02-25 03:09:48

grubenm wrote:

I apologize in advance for the several forum posting rules I'm sure to have broken.

None that I can discern.

There is no reason you cannot install two kernels in parallel. You may want to read this article on building a kernel. tl;dr You have multiple kernels in /boot, and select them from entries in your boot loader menu. If your custom kernel is borked, you can always still boot from a stock kernel.

grubenm · 2014-02-25 03:39:49

Your proposal is intriguing, though I have some questions:
(1) does booting from a different kernel mean the other installed packages have changed? If not, I'd still have a conflict when booting into the 3.13+ kernel with the 325-series nvidia packages
(2) does the ABS allow you to dip back into older kernels? Or would this method only allow me to customize a 3.13+ kernel and boot from it in addition to my stock kernel?

Last edited by grubenm (2014-02-25 03:41:04)

ewaller · 2014-02-25 04:02:15

1. Booting from a different kernel does not change the other packages that are installed; but... Kernel modules are kept in directories based upon the kernel name. This way each kernel can find its own modules. I do not have nvidia hardware, so you may need to look at the pkgbuilds for the nvidia packages. It may be that they install to the running kernel. They may also need to be modified to install to the correct directory.

2. The pkgbuild in the ABS will specify the kernel version to build. You can edit it to whatever kernel version you choose (provided the kernel is still on kernel.org)

I would start with the kernel and see how that goes, then take on the nvidia kernel modules.

grubenm · 2014-02-25 22:01:01

Ended up installing 'nvidia-304xx' instead of attempting to roll back to an earlier version of 'nvidia', thus circumventing the need for a kernel rollback while still achieving the performance objectives I was after.

For anyone else trying to get back their points-per-day on a GeForce GTX 600-series as Nvidia works on a fix for their 331+ drivers, I recommend that you switch over to the 'nvidia-304xx' package. I did so as follows:

sudo systemctl disable foldingathome.service && sudo systemctl stop foldingathome.service
sudo pacman -Rns nvidia
## I believe this also removed nvidia-utils as a dependency
sudo pacman -Rdds nvidia-libgl
## Note that I never reinstalled this package, and actually neither my tty nor F@H seemed
## to care.  You might care though in your personal use of the graphics card, and I admit I
## couldn't figure out how to get a 304xx-compatible version of this package installed.  Also,
## I used -Rdds because I have cairo installed and it complained with -Rns
sudo pacman -Rns opencl-nvidia
sudo pacman -S nvidia-304xx nvidia-304xx-utils opencl-nvidia-304xx
sudo reboot
sudo systemctl start foldingathome.service

Arch Linux

#1 2014-02-25 01:04:48

[Mooted] Kernel Rollback as part of 'nvidia' Rollback (folding@home)

#2 2014-02-25 03:09:48

Re: [Mooted] Kernel Rollback as part of 'nvidia' Rollback (folding@home)

#3 2014-02-25 03:39:49

Re: [Mooted] Kernel Rollback as part of 'nvidia' Rollback (folding@home)

#4 2014-02-25 04:02:15

Re: [Mooted] Kernel Rollback as part of 'nvidia' Rollback (folding@home)

#5 2014-02-25 22:01:01

Re: [Mooted] Kernel Rollback as part of 'nvidia' Rollback (folding@home)

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