SPEC CPU2017 Flag Description - Platform settings

Operating System Tuning Parameters

sched_cfs_bandwidth_slice_us
When Completely Fair Scheduler bandwidth control is in use, this parameter controls the amount of run-time (bandwidth) transferred to a run queue from the task's control group bandwidth pool. Small values allow the global bandwidth to be shared in a fine-grained manner among tasks, larger values reduce transfer overhead.
The default value is 5000

Firmware / BIOS / Microcode Settings

Adjacent Cache Line Prefetch
This BIOS option allows 2 options: "Enabled" and "Disabled".
This prefetcher always collects cache line pairs (128 bytes) from the main memory, providing that the data is not already contained in the cache. If this prefetcher is disabled, only one cache line (64 bytes) is collected, which contains the data required by the processor.
Default setting is "Enabled".
AES
This BIOS option allows 2 options: "Enabled" and "Disabled".
This option enables or disables Advanced Encryption Standard (AES) feature. This feature speeds up the process of encrypting information that usess AES.
Default setting is "Enabled".
C-States
This BIOS switch allows 2 options: "Enabled" and "Disabled".
This feature enables or disables CPU Power Management feature. This switch allows CPU to go to C-States when it's not 100% ulilized. If this option is disabled, all C-State related features are disabled.
Default setting is "Enabled".
C-State Pre-Wake
This BIOS switch allows 2 options: "Enabled" and "Disabled".
This feature enables or disables core/package early wake function from deep C-States using core/package C-State Pre-Wake timers.
Default setting is "Enabled".
DCU Streamer Prefetcher
This BIOS switch allows 2 options: "Enabled" and "Disabled".
This prefetcher is a L1 data cache prefetcher, which detects multiple loads from the same cache line done within a time limit, in order to then prefetch the next line from the L2 cache or the main memory into the L1 cache based on the assumption that the next cache line will also be needed.
Default setting is "Enabled".
DDR PowerDown and idle counter
This BIOS switch allows 2 options: "BIOS" and "PCODE".
This feature determines whether BIOS or hardware will control DDR powerdown modes and idle counter. When "PCODE" is selected, hardware algorithm controls the modes. When "BIOS" is selected BIOS controls the modes.
Default setting is "BIOS".
DMI Link ASPM Control
This BIOS option allows 4 options: "Disabled", "L0s", "L1" and "L0sL1".
The control of Active State Power Management(ASPM) supported on the Direct Media Interface(DMI) Link. L0s: L0s entry supported. L1: L1 entry supported. L0sL1: L0s and L1 entry supported. Disabled: No ASPM entry supported.
Default setting is "L1".
Energy Efficient Turbo
This BIOS option allows 2 options: "Enabled" and "Disabled".
This feature will opportunistically lower the turbo frequency to increase energy efficiency. If this option is disabled, turbo frequency will remain constant.
Default setting is "Auto".
Enhanced C-States
This BIOS option allows 2 options: "Enabled" and "Disabled".
This feature enables or disables C1E state. If this option is enabled, CPU will switch to minimum speed when all cores enter C-State.
Default setting is "Enabled".
Fan Control
This BIOS option allows 2 options: "Auto" and "Full".
The default setting is "Auto", which allows the system to control the fan speed according to the system temperature. If "Full" is selected, the system runs fans at 100% speed and it may improve the system performance. But it increases the power consumption of the system.
Default setting is "Auto".
Hardware Prefetcher
This BIOS option allows 2 options: "Enabled" and "Disabled".
This prefetcher looks for data streams on the assumption that if the data is requested at address A and A+1, the data will also presumably be required at address A+2. This data is then prefetched into the L2 cache from the main memory.
Default setting is "Enabled".
Hyper-Threading
This BIOS option enables or disables additional hardware thread which shares same physical core. Generally "Enabled" is recommended but disabling it makes sense for the application which requires the shortest possible response times.
Default setting is "Enabled".
Intel Virtualization Technology
This BIOS option enables or disables additional virtualization functions of the CPU. If the server is not used for virtualization, this option should be set to "Disabled". This can result in energy savings.
Default setting is "Enabled".
Intel(R) Speed Shift Technology
This BIOS option enables or disables Intel Speed Shif Technology support. If this option is enabled, CPU will operate in a way that with the hardware determined algorism and OS can hand control of the frequency and voltage back to the processor.
Default setting is "Enabled".
Native ASPM
This BIOS option allows 2 options: "Enabled" and "Disabled".
This feature enables or disables OS to control PCIe Active-state power management (ASPM) features. If this option is enabled, OS will control ASPM feature of PCIe devices.
Default setting is "Enabled".
Native PCIE Enable
This BIOS option allows 2 options: "Enabled" and "Disabled".
This feature enables or disables OS to control below features: Hot Plug, SHPC Native Hot Plug control, Power Management Events, PCIe Advanced Error Reporting control, PCIe Capability Structure control, and Latency Tolerance Reporting control.
Default setting is "Enabled".
Package C-State Demotion
This BIOS option allows 2 options: "Enabled" and "Disabled".
This feature enables or disables Package C-State Demotion for saving power by avoiding multiple transitions from deeper to shallower Package C-State. When OS requestes a shallower Package C-State to CPU in deeper Package C-State, this feature can change it to deeper Package C-State than requested automatically using history information.
Default setting is "Disabled".
Package C-State limit
This BIOS option allows 7 options: "C0", "C2", "C3", "C6", "C7", "C7S", and "Auto"
Package C-States is one of energy-saving options of the processor, which not only allow the individual cores of a processor, but the entire processor chip to be put into a type of sleep state. As a result, power consumption is even further reduced. But the "waking-up time" that is required to change from the lower package C-States to the active (C0) state is even longer in comparison with the CPU or core C-States. If the "C0" setting is made in the BIOS, the processor chip always remains active. It can improve the performance of latency sensitive workloads.
Default setting is "Auto".
Package C-State un-demotion
This BIOS option allows 2 options: "Enabled" and "Disabled".
This feature enables processor to switch back to the original requested deeper Package C-State considering cases where demotion was the incorrect decision in determing Package C-State depth.
Default setting is "Disabled".
Race To Halt (RTH)
This BIOS option allows 2 options: "Enabled" and "Disabled".
RTH will dynamically increase CPU frequency in order to enter Package C-State faster to reduce overall power.
Default setting is "Enabled".
REFRESH_2X_MODE
This BIOS option allows 3 options: "Disabled", "1- Enabled for WARM or HOT", and "2- Enabled HOT only".
This feature enables REFRESH 2X mode which maintains an acceptable overall error rate by increase DRAM refresh rate when temperature is WARM or HOT. 0 - Disabled. 1 - iMC enables 2xRefresh rate mode when thermal status is Warm or Hot. 2 - iMC enables 2xRefresh rate mode when thermal status is Hot
Default setting is "Disabled".
SW Guard Extensions (SGX)
This BIOS option allows 3 options: "Disabled", "Enabled", and "Software Controlled".
Intel(R) SGX is a CPU extension that applications can use to create and access private memory areas. When "Disabled" is selected, SGX is disabled and cannot be used by applications. When "Enabled" is selected, SGX is enabled and can be used by applications. The reserved size of the private memory is specified by the BIOS. When "Software Controlled" is selected, SGX is enabled and can be used by applications. The reserved size of the private memory is specified by the operating system (OS).
Default setting is "Software Controlled".
VT-d
This BIOS option enables or disables I/O virtualization functions of the CPU. If the server is not used for virtualization, this option should be set to "Disabled".
Default setting is "Enabled".