RTX Configuration 3 - Essential System Tunings
The following settings should be applied for stable RTX performance.
Trade-Off between Graphics Performance and Real-time Performance
The impact of graphics load on RTX should be considered. There are three main processing resources and each performance properties.
Integrated Graphics: Integrated Graphics that are built into the CPUs share the memory bus, memory resources, and power resources with the CPUs. For this reason, the load on the graphics controller can cause delays in the delivery of APIC timer interrupts in real-time cores, as well as performance degradation (For example, sudden latency of several 10us to several 100us or deteriorating throughput of packet transmission/reception). Note that high load on the integrated GPU by the desktop operation may be observed as a spike in the Task Manager performance screen (close to 100%) . On some systems, disabling graphics processor frequency changes for graphics loads in the BIOS may improve the problem.
Descrete Graphics: Discrete graphics are chips with arithmetic circuits specialized for specific numerical computations and applied to PCs as graphics cards. Graphics card may make the entire CPU wait several 10us to several 100us to read its own I/O space but the system can handle more demanding graphics processing. Disabling 3D rendering, etc. in the graphics card control panel may improve the problem of the CPU stolen time.
OS: When the Microsoft Basic Display Adapter Driver is applied as a display driver, much of the graphics processing is handled in software, reducing the impact of graphics processing on the RTX core (especially on CPUs). However, output resolution and multi-display and system graphics processing performance may be limited.
The table below shows the main graphics configurations available for general consumer and industrial PCs.
No. |
CPU Type |
Is a graphics card inserted? |
Graphics Driver applied in Device Manager |
Remarks |
|---|---|---|---|---|
1 |
CPU without Graphics Processing Unit |
Yes |
Descrete Graphics Driver |
This is one of the common default configuration of the PCs with graphics card. |
Microsoft Basic Display Adapter Driver |
This is a system configuration with the least graphics impact for RTX. |
|||
2 |
CPU with Integrated Graphics Processing Unit |
Yes |
Descrete Graphics Driver |
This is one of the common default configuration of the PCs with graphics card. |
No |
Integrated Graphics Driver |
This is one of the common default configuration of the PCs. |
||
Microsoft Basic Display Adapter Driver |
This is a system configuration that has relatively little graphics impact for RTX. |
Follow the steps below to disable graphics drivers of integrated GPUs and apply the Microsoft Basic Display Adapter.
From the Control Panel, go to “Device Manager”.
In the pane, expand Display adapters. Select Graphics Adapter starting with “Intel”, Right-click on the adapter and click “Disable”. Discrete graphics drivers should be disabled as well. Basic display adapters are automatically applied when all dedicated graphics drivers are disabled.
Right-click on the Windows start menu, click on “Run”.
Enter “dxdiag”, wait until the DirectX Diagnostic Tool screen appears.
Go to the “Display” tab of the screen. Check to see if the “Name” entry is the Microsoft Basic Display Adapter.
For additional information, please refer to the following technical note of IntervalZero (the developer of RTX).
http://softservo.com/pub/RTX_Doc/RTX64/TechNote/Causes_and_Management_of_Interrupt_Latencies.pdf
SMI Activities
SMI (System Management Interrupt) causes delays of up to hundreds of microseconds.
Certain SMI activities may be suppressed by disabling certain features of the task scheduler.
Latency caused by SMI activity may not be reflected in the RTX HAL timer context, and the latency may not be reflected in the HAL timer clock-based statistics (Interrupt Interval, etc.).
The problem can be remedied to some extent by setting the following registry entries (In RTX4.x, this improvement is built into the RTOS as a standard feature, so it is not necessary to explicitly configure the registry.)
Key : HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\RTX64 Name : EnableTimerTickCompensation Type : REG_DWORD Value : 1
For additional information, please refer to the following technical note of IntervalZero (the developer of RTX).
http://softservo.com/pub/RTX_Doc/RTX64/TechNote/Causes_and_Management_of_Interrupt_Latencies.pdf
Assigning RTX cores to Performance-cores in a hybrid architecture
Running the WMX3 engine on a low-power core may degrade real-time performance. For this reason, it is recommended not to assign RTX to those cores
Some architectures with Efficient-cores, such as Intel? Alder Lake (12th gen Intel CPUs), a new hybrid architecture that combines Efficient-cores and Performance-cores, should address this issue.
How to assign RTX to Performance-cores
If a system has four Efficient-cores and four Performance-cores, the processor numbers assigned to the Performance-cores are 0, 1, 2, and 3; the processor numbers assigned to the Efficient-cores are 4, 5, 6, and 7.
RTX cores are allocated in ascending order starting with processor number N after Windows cores are allocated starting with processor number 0. For example, if 2 cores are assigned to RTX, processor number 6 is used for RTX Core0 and processor number 7 for RTX Core1.
Based on these specifications, in order for the cores allocated to RTX to be Performance-cores, the cores must be allocated so that the sum of the Windows cores and RTX cores is the sum of the Performance-cores.
To assign cores, use the following RTX utility.
C:\Program Files\IntervalZero\Common\bin\RTX64ActivationGUI.exe
How to check for Efficient-cores
IntervalZero (the developer of RTX) provides a HyblidInfo utility to check the cores.
http://softservo.com/pub/RTX/ProcessorHybridInfoUtility_07082022_2.zip
Follow the steps below to check the type of each core.
Download the utility and unzip it. Note: Steps 5 and 8 are performed from the destination decompression folder moved by the cd command.
Copy HybridInfoDrv.sys to C:\Windows\System32\drivers folder.
In the Windows start menu, enter “regedit”, right click on “Registry Editor”, and click on “Start as administrator”. Click “File” -> “Import” and import HybridInfoDrv.reg to the system.
In the Windows start menu, enter “cmd”, right click on “Command Prompt”, and click on “Start as administrator”.
In the Command Prompt, enter “certutil -addstore “TrustedPublisher” HybridInfoDrv.cer”.
Reboot machine.
In the Windows start menu, enter “cmd”, right click on “Command Prompt”, and click on “Start as administrator”.
In the Command Prompt, enter “net start HybridInfoDrv” and enter “HybridInfo”.
From the output information, check the Efficient-cores displayed as E_Core and the Performance-cores displayed as P_Core. If “The processor is not a hybrid part.” is displayed, it does not matter which core RTX is assigned to, as there are no power saving cores in the system.
For additional information, please refer to the following technical note of IntervalZero (the developer of RTX).
http://softservo.com/pub/RTX_Doc/RTX64/TechNote/Using_RTX64_on_a_Performance_Hybrid_Architecture.pdf
Adjust BIOS Settings that affect Real-time Performance
The following table lists examples of the BIOS configuration parameters that affect real-time performance.
No. |
BIOS Settings |
Descriptions |
Recommended value |
|---|---|---|---|
1 |
HyperThreading |
Hyper-Threading allows multiple threads to run on each core. |
Disable |
2 |
RC6 (Render Standby), Gfx Low Power Mode |
Power-saving features of integrated graphics processors |
Disable |
3 |
C-state |
Power management function by C-state (Processor Power States: C0/C1/C2/C3…) for example “C1 State”, “C1E State”, “Enhanced HALT State”. |
Disable |
4 |
P-state (including hardware P-State) |
Power management function by P-state (Processor Performance States: P0/P1/P2/P3…) for example “EIST(Enhanced Intel SpeedStep Technology)”, “Intel Speed Shift”, “Intel Turbo Boost”, “Race To Halt”, “Energy Efficient Turbo”. |
Disable |
5 |
L-state |
Power management function by L-state (Active State Power Manegement: L0s/L0/L1/L2/L2R/L3/L3R…) for example “Delay Enable DMI ASPM”, “DMI Link ASPM”, “Native ASPM”, “PCIe ASPM”, “ASPM Support”, “PEG ASPM”. |
Disable |
6 |
Power Saving Mode of the System Agent (SA) |
Power-saving features provided by BIOS. |
Disable |
7 |
TPM |
Trusted Platform Module |
Disable |
About Hyper-Threading
It is recommended to disable Hyper-Threading from the BIOS if the CPU supports Hyper-Threading.
If Hyper-Threading is enabled, RTX may not guarantee real-time performance.
To disable Hyper-Threading on Windows10, go to the BIOS settings screen and select the setting related to Hyper-Threading mode and set it to disabled.
For additional information, please refer to the following technical note of IntervalZero (the developer of RTX).
If you disable Hyper-Threading after assigning CPU cores to RTX, the RTX subsystem and/or the Activation and Configuration utility may fail to start. In this case, follow these steps:
In the Windows start menu, enter “cmd”, right click on “Command Prompt”, and click on “Start as administrator”.
In the Command Prompt, enter “cd %rtx64common%\bin” to navigate to C:\Program Files\IntervalZero\Common\bin.
In the Command Prompt, enter “Rtx64ActivationUtil.exe -w 3 -r 1”, where the number after -r should be replaced by the number of cores allocated to RTX and the number after -w should be replaced by the number of cores allocated to Windows (the number of cores in the CPU minus the number of cores allocated to RTX).
Also see the RTX64 Help
at:https://help.intervalzero.com/product_help/RTX64/Content/PROJECTS/Utilities/SystemConfiguration.htm
Disable Display Automatic Shutdown
Jitter of several 10us to 100us may occur depending on the ON and OFF of the display output. For this reason, please disable automatic shutdown of the display in the control panel.