Nvidia DU-07764-001 User Manual
DU-07764-001 | September 2015
User Guide
GPUMODESWITCH
Version
Date
Authors
Description of Change
1.0
8/30/2015
AC
Initial release
DU-07764-001
DOCUMENT CHANGE HISTORY
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Chapter 1. Introduction.................................................................................. 1
1.1 Compute and graphics mode ........................................................................ 1
1.2 When to use graphics mode ......................................................................... 2
1.3 Supported products ................................................................................... 3
Chapter 2. Using gpumodeswitch .................................................................... 4
2.1 Supported environments ............................................................................. 4
2.2 What’s in the package ................................................................................ 4
2.3 Running gpumodeswitch ............................................................................. 5
2.3.1 Listing current GPU modes ................................................................... 5
2.3.2 Switching GPU modes ........................................................................ 6
2.4 Linux bootable images ................................................................................ 9
2.4.1 Booting directly from ISO ................................................................... 10
2.4.2 Booting from a USB flash key .............................................................. 10
2.5 Troubleshooting ....................................................................................... 12
2.5.1 Unloading an existing NVIDIA driver ...................................................... 12
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LIST OF FIGURES
Figure 1 Connecting gpumodeswitch.iso via server remote management ................. 10
Figure 2 Launching an administrator command prompt ..................................... 11
LIST OF TABLES
Table 1 Compute mode settings ................................................................. 1
Table 2 Graphics mode settings .................................................................. 2
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Setting
Value
Notes
Classcode
3D Controller
This classcode indicates to operating systems (OS) that the GPU is not
intended for use as a primary display device.
Memory BAR
8 gigabytes
Tesla GPUs expose a large memory base address register (BAR) for direct
access to the framebuffer from the CPU, and other PCI Express devices.
I/O base BAR
Disabled
The GPU need not consume any legacy I/O resources when used as a non-
display device.
ECC protection
Enabled
Error Correcting Code (ECC) is enabled on the GPU framebuffer to protect
against single- and multi-bit memory errors.
Chapter 1. INTRODUCTION
gpumodeswitch is a command-line tool that is used to switch supported NVIDIA GPUs
between compute and graphics mode. This chapter describes these modes and when to
use them. Chapter 2 describes how to use gpumodeswitch.
1.1 COMPUTE AND GRAPHICS MODE
NVIDIA Tesla GPUs are shipped in a configuration optimized for high-performance
compute (HPC) applications:
Table 1 Compute mode settings
Collectively this GPU configuration is referred to as compute mode. While compute mode
is optimal for HPC usage, it can cause compatibility problems with OS and hypervisors
when the GPU is used primarily as a graphics device:
Some OS require that the GPU advertise a VGA display controller classcode in order
for the GPU to be used as a primary graphics device.
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Introduction
Setting
Value
Notes
Classcode
VGA Controller
This classcode indicates to OS that the GPU can function as a primary
display device.
Memory BAR
256 megabytes
The GPUs a smaller memory BAR for direct access to the framebuffer.
I/O base BAR
Enabled
The GPU exposes an I/O BAR to claim the resources require to operate as
a VGA controller.
ECC protection
Disabled
ECC protection is disabled by default, though it can still be enabled by
use of the nvidia-smi management tool
Note: consult individual NVIDIA product release notes for the latest information on
compatibility with compute and graphics modes.
Some hypervisors cannot support passthrough of GPUs with large memory BARs to
guest virtual machines.
To address these problems, certain NVIDIA Tesla GPUs support setting the GPU into
graphics mode:
Table 2 Graphics mode settings
The mode of the GPU is established directly at power-on, from settings stored in the
GPU’s non-volatile memory. gpumodeswitch is used to program the mode of the GPU
by updating the GPU’s non-volatile memory settings.
1.2 WHEN TO USE GRAPHICS MODE
We recommend that graphics mode be used whenever supported Tesla products are
used in the following scenarios:
GPU passthrough with hypervisors that do not support large BARs. At the time of
publication, this includes Citrix XenServer 6.2, 6.5, VMware ESXi 5.1, 5.5, 6.0, Red Hat
Enterprise Linux 7.0, 7.1.
GPU passthrough to Windows VMs on Xen and KVM hypervisors.
GRID Virtual GPU deployments.
VMware vSGA deployments.
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