NVIDIA™ driver for FreeBSD/Linux: performance and power saving hints

Contents

• The document revisions history
• TO DO list
• Performance and power saving
  • General information
  • Theory
  • Practice
  • Configuration examples
• FreeBSD port of binary NVIDIA driver
• Compatibility
• Useful links

Following information may be useful for NVIDIA chipset-based notebook owners with FreeBSD, Solaris or Linux (Ubuntu/Gentoo/Fedora/RedHat/Debian etc). However, theoretical part of the article is correct for NVIDIA drivers for Microsoft Windows systems.

Note that fan speed on NVIDIA video cards are controlled by different mechanism not described in the article.

Note also that this is not an official documentation and some statements may be wrong!

The document revisions history

• 2009-02-23 - FreeBSD section cleanup
• 2008-12-10 - add more illustrations, correct Linux-specific things, add compatibility section
• 2008-12-09 - initial revision

TO DO list

• Power consumption and time of work on battery measurements in different modes
• User defined frequencies for 2D/3D operation modes and overclocking ;)

Performance and power saving

General information

Performance levels

NVIDIA binary driver supports several performance levels. Each one has two parameters: GPU clock frequency and on-board memory clock frequency (if the card has one). To see supported performance levels you may use 'nvidia-settings' command. In the example below we have 3 performance levels:

$ nvidia-settings -q GPUPerfModes -t
perf=0, nvclock=100, memclock=0 ; perf=1, nvclock=350, memclock=0 ; perf=2, nvclock=425, memclock=0

Notes:

• The parameter is read-only.
• memclock=0 means that on-board memory is absent.
• Number of available performance levels may vary for different cards (I saw cards with 1, 3 and 4 levels).
• For the same performance level there may be different memclock values for different screen mode BPS (16/32).

NVIDIA driver works in one of these levels each period of time. Following commands will show you current performance level and current frequency parameters:

$ nvidia-settings -q GPUCurrentPerfLevel -t
2

$ nvidia-settings -q GPUCurrentClockFreqs -t
425,666

As for "425,666" in the example above - current GPU frequency is 425 MHz, but the card has no on-board memory so there should be "425,0" (memclock=0 for perf=2). Looks like a bug in NVIDIA driver or nvidia-settings tool.

You should not monitor current state of GPUCurrentPerfLevel and GPUCurrentClockFreqs parameters using 'nvidia-settings -q all' command - this artificially rises current performance level.

NVIDIA X.org driver can detect power source. To see the current state check 'GPUPowerSource' read-only parameter (0 - AC, 1 - battery):

$ nvidia-settings -q GPUPowerSource -t
1

Performance modes

Another one read-only NVIDIA driver parameter is 'GPUCurrentPerfMode' - Performance mode. Possible values are:

• 1 - Desktop (2D) - 3D features are not used at the moment;
• 2 - Maximum Performance (3D) - some application is using 3D features.

To switch to the 3D mode you may run 'glxgears' application from 'mesa-demos' package for example (graphics/mesa-demos port for FreeBSD users).

There is confortable GUI to monitor current status of the driver - just run 'nvidia-settings' without command-line parameters:

Theory

You may configure power saving behavior for AC and battery sources separately. If your drivers (either NVIDIA or system ones) don't detect current power source correctly, you have to use only one configuration (usually for AC source - check current 'GPUPowerSource' parameter).

Clock frequency control strategies

You may choose clock frequency control strategy for each power source. At the moment we have:

• strategy=22(hexadecimal) - fixed clock frequency strategy - the card works with a fixed frequency regardless of GPU usage;
• strategy=33(hexadecimal) - adaptive clock frequency strategy - the card works on maximum power saving level (perf=0) until your applications start to heavily use the card resources, in the case GPU rises current performance level and when the resources are not used anymore, GPU lowers frequency (on one performance level each 15 seconds):

PowerMizer modes

You can not configure some performance level to be used for fixed clock frequency strategy. Instead there are three possible PowerMizer modes for the fixed clock frequency configuration:

• mode=1 - Maximum performance - usually performance level with highest 'perf' (performance level) index is used,
• mode=2 - Balanced - one of medium performance level is used,
• mode=3 - Maximum power saving - usually perf=0 performance level is used.

Note that you have only three PowerMizer modes regardless of performance levels number and the values have opposite meaning. Yeah, looks freaky.

PerfLevelSrc - strategies assigment

There is special NVIDIA driver parameter 'PerfLevelSrc'. Its hexadecimal value format is

0x[Battery source strategy][AC source strategy]

Look at following examples:

• PerfLevelSrc=0x2222 - fixed PowerMizer mode (and appropriate fixed frequency) is used for battery power source and fixed PowerMizer mode is used for AC power source, these PowerMizer modes may be the same or different
• PerfLevelSrc=0x2233 - fixed PowerMizer mode is used for battery power source and adaptive clock frequency strategy is used for AC power source
• PerfLevelSrc=0x3322 - fixed adaptive clock frequency strategy is used for battery power source and PowerMizer mode is used for AC power source
• PerfLevelSrc=0x3333 - adaptive clock frequency strategy is used for battery and AC power sources

There are two NVIDIA driver parameters to configure fixed clock frequency strategy:

• 'PowerMizerDefault' - contains PowerMizer mode value to be used for battery power source,
• 'PowerMizerDefaultAC' - contains PowerMizer mode value to be used for AC power source.

Practice

Now we are ready to configure NVIDIA driver.

'RegistryDwords' option from appropriate NVIDIA device section of 'xorg.conf' file is used for the configuration. Minimal configuration may look like follows:

Section "Device"
  Identifier "NVIDIA GeForce"
  Driver     "nvidia"
  Option     "RegistryDwords" "<performance and power saving configuration>"
EndSection

The 'RegistryDwords' option format is "parameter1=value1 [; parameter2=value2 ...]" and usually it contains following parameters:

"PowerMizerEnable=0x1; PerfLevelSrc=0x<value1>; PowerMizerDefault=0x<value2>; PowerMizerDefaultAC=0x<value3>"

You have to reload NVIDIA kernel module and restart X.org server to apply the option. Full system reboot will also help.

Notes:

• don't forget about hexadecial prefixes - '0x', especially for 'PerfLevelSrc' parameter;
• don't leave trailing ';' in RegistryDwords - Linux version of NVIDIA driver for X.org doesn't support it;
• you must not split RegistryDwords option into several RegistryDwords options, only the first one will be applied.

Configuration examples

Look at four popular 'RegistryDwords' option values:

• on battery - max power saving, on AC - max performance

  "PowerMizerEnable=0x1; PerfLevelSrc=0x2222; PowerMizerDefault=0x3; PowerMizerDefaultAC=0x1"
  

• on battery - max power saving, on AC - adaptive strategy (my favorite)

  "PowerMizerEnable=0x1; PerfLevelSrc=0x2233; PowerMizerDefault=0x3"
  

• on battery - adaptive strategy, on AC - max performance

  "PowerMizerEnable=0x1; PerfLevelSrc=0x3322; PowerMizerDefaultAC=0x1"
  

• adaptive strategy for any power source

  "PowerMizerEnable=0x1; PerfLevelSrc=0x3333"
  

FreeBSD port of recent binary NVIDIA driver

Recent x11/nvidia-driver port from FreeBSD ports collection should work fine.

• If you have problem with power source detection, make sure that ACPI on your system reports power source changes correctly. After the command

  $ cat /var/run/devd.pipe | grep ACAD
  

  you should see following line when you switch on battery power

  !system=ACPI subsystem=ACAD type=\_SB_.PCI0.AC0_ notify=0x00
  

  and for AC power there should be

  !system=ACPI subsystem=ACAD type=\_SB_.PCI0.AC0_ notify=0x01
  

  'type' values may vary, but other parameters should be exactly as specified above.

  If you don't see appropriate messages, check 'acpi_acad' device and 'devd' daemon presense and status of 'hw.acpi.acline' sysctl (0 - battery, 1 - AC).

  $ devinfo |grep acpi_acad
      acpi_acad0
  
  $ /etc/rc.d/devd status
  devd is running as pid 562.
  
  $ sysctl hw.acpi.acline
  hw.acpi.acline: 1
  

• You may wish to configure performance and power saving mode - see details above.
• To apply the driver installation (or replacement) you should load (or reload) nvidia.ko kernel module and restart your X.org server. Full FreeBSD server reboot will also help.

  If you haven't used the driver before, you should configure X.org accordingly.

It is also recommended to install x11/nvidia-settings FreeBSD port to monitor current driver state.

Compatibility

FreeBSD 7.1-PRERELEASE i386

OS/kernel release/version	NVIDIA hardware (PCI ID)	NVIDIA driver version	Performance levels	Features
				power source detection	adaptive strategy	fixed frequency - PowerMizer modes
						1 - max perf.	2	3 - max power saving
on-board GeForce Go 6100 (0x10de:0x0247, rev=0xa2)	180.18	perf=0, nvclock=100, memclock=0; perf=1, nvclock=350, memclock=0; perf=2, nvclock=425, memclock=0	yes	yes	perf=2	perf=1	perf=0
Notes: Works fine.
Linux 2.6.27-9-generic x86_64	2x GeForce 8700M GT SLI (0x10de:0x01b3, rev=0xa3)	180.11.02	perf=0, nvclock=170, memclock=100; perf=1, nvclock=275, memclock=300; perf=2, nvclock=625, memclock=800	yes	no	no	no	no
Notes: Default behavior with Option "SLI" "false" or Option "SLI" "SFR" is max performance on AC and max power saving on battery. PerfLevelSrc has no effect.

Useful links

• X.org drivers for NVIDIA video on nvnews.net forum