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nvidia interview questions

Top nvidia frequently asked interview questions


How can I get nVidia CUDA or OpenCL working on a laptop with nVidia discrete card/Intel Integrated Graphics?

Background: I'm a 3D artist (as a hobby) and have recently started using Ubuntu 12.04 LTS as a dual-boot with Windows 7. It's running on my a fairly new 64-bit Toshiba laptop with an nVidia GeForce GT 540M GPU (graphics card). It also, however has Intel Integrated Graphics (which I suspect Ubuntu's been using).

So, when I render my 3D scenes to images on Windows, I am able to choose between using my CPU or my nVidia GPU (faster). From the 3D application, I can set the GPU to use either CUDA or OpenCL. In Ubuntu, there's no GPU option.

After doing (too much?) research on the issues with Linux and the nVidia Optimus technology, I am slightly more enlightened, but a lot more confused.

I don't care one bit about the Optimus technology, as battery life is not by any means an issue for me.

Here's my question: What can I do to be able to use CUDA-utilizing programs (such as Blender) on my nVidia GPU in Ubuntu? Will I need nVidia drivers? (I have heard they don't play nicely with Optimus setups on Linux.) Is there at least a way to use OpenCL on my GPU in Ubuntu?


Source: (StackOverflow)

NVIDIA drivers not working after upgrade. Why can I only see terminal?

Tonight I upgraded to 11.04. Problems. Once I had finished the upgrade, I restarted my computer as it told me too. When I got past the ubuntu 11.04 (purple background orange dots), it simply went to the terminal and asked me to log in. I tried to restart the X server with "sudo service gdm restart" but no display popped up. I happened to have a few NVIDIA drivers in my downloads file also so I gave these a try, but the "install script" failed.

After all this I booted Ubuntu in graphic failsafe mode. I then decided to see what would happen if I removed the proprietary driver. Upon doing this and rebooting my Ubuntu booted into graphical mode "yay!". So without the Nvidia drivers I can finally see something other than terminal, but, I need those NVIDIA drivers for my work. So what can I do? I have tried installing the new NVIDIA linux drivers from the NVIDIA website, and have tried Installing the recommended driver via "additional drivers", but both have resulted in my being stuck in terminal.

If you can help or give me some advice PLEASE DO! I am really in a very bad situation...


Source: (StackOverflow)

Nvidia driver doesn't work in 12.10

I have GeForce GTX 560 Ti. I's worked fine in 12.04 with nvidia drivers. Unfortunately, after todays 12.10 update, something broke down.

I've tried nvidia-current, nvidia-current-updates and nvidia-experimantal. Always the same behaviour: Bad resolution in lightdm, after logging nothing except wallpaper. No unity panels, "win" key doesn't work.

After removing nvidia drivers everything work.


Source: (StackOverflow)

15.04 and Nvidia: login loop

Upgraded 14.10 to 15.04, desktop fails to load past login screen. I type in my password, hear a failure sound byte, back to login screen. Also can't boot off a 15.04 thumb drive created with another PC. Guest account does same thing. Tried removing all nvidia driver packages, tried messing with .Xauthority, tried using gdm instead of lightdm (failed even worse: no login screen at all). Tried reinstalling ubuntu-desktop. Get error code of ACPI PCC probe failed, starting 219 or something like that.

Currently running 15.04 off said thumb drive...on an another PC with AMD integrated graphics, no issues.

15.04 doesn't like Nvidia graphics cards. Please help!


Source: (StackOverflow)

How do I stop video tearing? (Nvidia prop driver, non-compositing window manager)

I have that problem which seemingly afflicts many using the proprietary Nvidia driver:

Video tearing: fine horizontal lines (usually near the top of my display) when there is a lot of panning or action in the video.

(Note: switching back to the default nouveau driver is not an option, as its seemingly nonexistent power-management drains my battery several times faster)

I've tried Totem, Parole, and VLC, and tearing occurs with all of them. The best result has been to use X11 output in VLC, but there is still tearing with relatively moderate action.

Hardware: MacBook Air 3,2 -- which has an Nvidia GeForce 320M.

There are two common fixes for tearing with Nvidia prop drivers:

  1. Turn off compositing, since Nvidia proprietary drivers don't usually play nice with compositing window managers on Linux (Compiz is an exception I'm aware of). But I use an extremely lightweight window manager (Awesome window manager) which is not even capable of compositing (or any cool effects). I also have this problem in Xfce, where I have compositing disabled.

  2. Enabling sync to VBlank. To enable this, I set the option in nvidia-settings and then autostart it as nvidia-settings -l with my other autostart programs. This seems to work, because when I run glxgears, I get:

    $ glxgears
     Running synchronized to the vertical refresh.  The framerate should be
    approximately the same as the monitor refresh rate.
    303 frames in 5.0 seconds = 60.500 FPS
    300 frames in 5.0 seconds = 59.992 FPS
    

    And when I check the refresh rate using nvidia-settings:

    $ nvidia-settings -q RefreshRate
    Attribute 'RefreshRate' (wampum:0.0; display device: DFP-2): 60.00 Hz.
    

    All this suggests sync to VBlank is enabled. As I understand it, this is precisely designed to stop tearing, and a lot of people's problem is even getting something like glxgears to output the correct info. I don't understand why it's not working for me.

xorg.conf: http://paste.ubuntu.com/992056/

Example of observed tearing:: video tearing


Source: (StackOverflow)

How do I disable the "Nouveau Kernel Driver"?

I'm trying to install proprietary nvidia graphics driver I downloaded from nvidia website. It will not install because it says that the "Nouveau kernel driver" needs to be disabled first.

I opened synaptic and uninstalled everything that had nvidia, nouveau, or jockey in its name. It still won't work.

What exactly do I need to do to disable the "Nouveau kernel driver"?


Source: (StackOverflow)

Error loading libGL.so.1

When attempting to run various pieces of software (notably Steam and Yenka), I have come across an error similar to this: error while loading shared libraries: libGL.so.1: cannot open shared object file: No such file or directory

I'm running a 64 bit system, with an NVidia Optimus card (I dual boot for certain windows only software that requires a dedicated graphics card). I have bumblebee installed, and I am using the nvidia-current driver, rather that one downloaded from NVidia, as recommended.

The library (libGL.so.1) is not present in the top directory of /usr/lib, however it is present in /usr/lib32/nvidia-current, as a softlink to /usr/lib32/nvidia-current/libGL.so.304.64.

A section of the output from ldconfig -p:

libGL.so.1 (libc6,x86-64, OS ABI: Linux 2.4.20) => /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1
libGL.so (libc6,x86-64, OS ABI: Linux 2.4.20) => /usr/lib/x86_64-linux-gnu/libGL.so
libGL.so (libc6,x86-64, OS ABI: Linux 2.4.20) => /usr/lib/x86_64-linux-gnu/mesa/libGL.so

Obviously a library with that name is being loaded, but they are located in /usr/lib/x86_64-linux-gnu, however installed software doesn't seem to able to 'see' it. For Steam, running it with optirun causes it to work, but this is not the case for Yenka. I assume that optirun causes the library stored in /usr/lib32/nvidia-current to be used, which allows Steam to run, so I can't understant why Yenka won't run.

Can anyone explain why software can't see the normal mesa library, and why Yenka refuses to run with the nvidia-current library?


Source: (StackOverflow)

Problems after upgrading to 14.04 (only background and pointer after login) [duplicate]

This question already has an answer here:

After upgrading from 12.04 to 14.04 I could log in to my X session (albeit with really low graphics). While trying to fix the graphics, I managed to break the X session.

Now, after typing my password in the unity-greeter, the items disappear and I can only see the desktop background and the pointer. This happens for every user. I can still log in in tty's. How can I solve this?

Also, I cannot seem to be able to install nvidia-current as it tries to install nvidia-304 and it depends on old video-abi libraries. Is there a way to tell the package manager that nvidia-current should use a newer version?


Source: (StackOverflow)

Installing and testing CUDA in Ubuntu 14.04

I am uncertain about how to install CUDA in my system. looking around there are many tutorials about cuda on 12.04 LTS and a few on 13.04 and 13.10, but they all talk about acquiring a deb package from the NVidia CUDA developer zone.

Well NVidia does not offer a Debian package for 14.04 as of yet.

However, there is a promising package in apt repository: nvidia-cuda-toolkit.

The problem is that I didn't find any example with it. At least not the examples that are referred to in cuda6 online documentation section 4.11.

I should mention that the toolkit installed is v5.5, not v6 but I haven't found documentation for cuda v5.5 on the NVidia website.

So I can verify that nvcc is there, but nothing further than that. How can I get some examples to run to verify the CUDA is installed properly?


Source: (StackOverflow)

Remove nVidia driver and go back to Nouveau

I've installed nVidia driver successfully but I want to go back to Nouveau driver and eliminate any xorg.conf file created by nVidia config tools.

What is the proper way to do it? (not ending up with no driver at all, or no X server)


Source: (StackOverflow)

nvidia-libopencl1-331 has to be removed before installing WINE

I just installed Ubuntu 14.04 64-bit and enabled the nvidia drivers. Now I am trying to install WINE but I get the message:

nvidia-libopencl1-331 has to be removed before installing WINE (translated from Dutch). Is this a bug? Or should I proceed removing this package?


Source: (StackOverflow)

Graphics issues after installing Ubuntu 16.04 with NVIDIA graphics

I installed or upgraded to Ubuntu 16.04, but I'm having some problems with my graphics card.

  • The display is blank
  • The display flickers
  • Items on the screen do not display correctly
  • Certain programs complain of graphics issues
  • The computer boots to low-graphics mode

  • Your specific issue may not be here, but try the solutions described in the answers, anyway.

This question is very broad, but each one of these issues likely has one solution.


If you are experiencing a login loop, check the last part of my answer.


If you experience one of the listed issues and have your own solution (mine didn't work, or there's a faster way), feel free to post another POLITE answer, describing your problem and how you fixed it.


Source: (StackOverflow)

How to install NVIDIA.run?

I have a Nvidia Ge force Ge6150 SE graphics card. I am running ubuntu 12.04. When I try to install the .run file it fails. It shows the message like this:

enter image description here

I Itried to install it after uninstalling the old driver.still same message. here is the log file.

nvidia-installer log file '/var/log/nvidia-installer.log' creation time: Mon Jun 11 05:46:17 2012 installer version: 295.53

PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games

nvidia-installer command line: ./nvidia-installer

Using: nvidia-installer ncurses user interface -> The file '/tmp/.X0-lock' exists and appears to contain the process ID '1062' of a >runnning X server. ERROR: You appear to be running an X server; please exit X before installing. For >further details, please see the section INSTALLING THE NVIDIA DRIVER in the README >available on the Linux driver download page at www.nvidia.com. ERROR: Installation has failed. Please see the file '/var/log/nvidia-installer.log' >for details. You may find suggestions on fixing installation problems in the README >available on the Linux driver download page at www.nvidia.com.

but no such file is shown in the process manager. Help me!!


Source: (StackOverflow)

How do I install the Nvidia driver for a GeForce GT 630

I recently installed 14.04.

But now I need a new driver for my nVidia GeForce GT 630. The former driver was rejected as not compatible with the 64-bit. I found that other driver and when I wanted to install it in the terminal with sh I was called first to stop the x-server. It cannot be installed with running x-server.

So how do I install them?


Source: (StackOverflow)

How can I uninstall a nvidia driver completely ?

As expected, Nvidia drivers have reduced my customizations. I can't login to Unity 3D session. I can't find any content to help me to uninstall the driver and I don't know what to do as I have never uninstalled them before.


Source: (StackOverflow)