SPEC CPU2017 Flag Description - Platform settings

Operating System Tuning Parameters

ulimit
This sets user limits of system-wide resources and can set the stack size to n kbytes, or unlimited to allow the stack size to grow without limit. Some common ulimit commands may include:
Kernel parameters
The following Linux Kernel parameters were set for better optimize performance.

Firmware / BIOS / Microcode Settings

ACPI _CST C1 Declaration
This BIOS switch allows 3 options: "Disabled", "Enabled", and "Auto". This feature determines whether or not to declare the C1 state to OS. Default is Auto.
cTDP
Configures the maximum power that the CPU will consume, up to the platform power limit. Valid values vary by CPU model. If value outside the valid range is set, the CPU will automatically adjust the value so that it does fall within the valid range. When increasing cTDP, additional power will only be consumed up to the Package Power Limit, which may be less than the cTDP setting.
ModelMinimum cTDPMaximum cTDP
EPYC 7502180200
EPYC 7452155180
EPYC 7402180200
EPYC 7352155180
EPYC 7302155180
EPYC 7282120150
EPYC 7262155180
EPYC 7252120150
Determinism Slider
This BIOS switch allows 3 options: "Auto", "Power", and "Performance". This feature is for the determinism to control performance. "Auto" setting uses default values for deterministic performance control. "Power" setting provides predicable performance across all processors of the same type. "Power" setting maximizes performance withing the power limits defined by cTDP. Default is "Auto".
DRAM Scrub Time
This feature controls the time between DRAM Scrubbing, which cyclically accesses the main memory of the system in the background regardless of the operating system in order to detect and correct memory errors in a preventive way. This BIOS switch allows 8 options: "Disabled", "1 hour", "4 hours", "8 hours", "16 hours", "24 hours", "48 hours", and "Auto". "Disabled" option disables the feature of DRAM Scrubbing and it may result in improving the performance under certain circumstances but increases the probability of discovering memory errors in case of active accesses by the operating system. Until these errors are correctable, the ECC technology of the memory modules ensures that the system continues to run in a stable way. However, too many correctable memory errors increase the risk of discovering non-correctable errors, which then result in a system standstill.
Global C-state Control
This BIOS switch allows 2 options: "Disabled", "Enabled, and "Auto". This feature controls IO based C-state generation and DF C-states. Default is "Auto"
L1 Stream HW Prefetcher
This BIOS switch allows 2 options: "Disabled", "Enabled, and "Auto". This feature allows enabling or disabling of L1 Stream HW Prefetcher. Auto. Default is "Auto".
L2 Stream HW Prefetcher
This BIOS switch allows 2 options: "Disabled", "Enabled, and "Auto". This feature allows enabling or disabling of L2 Stream HW Prefetcher. Default is "Auto".
NUMA nodes per socket
This BIOS switch allows 5 options: "NPS0", "NPS1", "NPS2", "NPS4", and "Auto". This feature specifies the number of desired NUMA nodes per populated socket in the system: Default is "Auto".
Package Power Limit
This BIOS switch specifies the maximum power that each CPU package may consume in the system. The actual power limit is the maximum of the Package Power Limit and cTDP.
SMT Control
This BIOS switch allows 2 options: "Auto" and "Disabled". This feature allows enabling or disabling of symmetric multithreading on processors. When enabled, each physical processor core operates as two logical processor cores. When disabled, each physical core operates as only one logical processor core. "Auto" enables this feature and can improve overall performance for applications that benefit from a higher processor core count. Default is "Disabled".
SVM Mode
This BIOS switch allows 2 options: "Enabled" and "Disabled". This is CPU virtualization function. With SVM enabled virtual machines can be installed on the system. Default is "Enabled".