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 SRAT L3 Cache As NUMA Domain
This BIOS switch controls to generate the distance information of each L3 Cache as a NUMA node in ACPI Static Resource Affinity Table (SRAT). When this feature is enabled, the BIOS will expose L3 Cache information as a NUMA node in SRAT and allow the operating system to access and use the information to optimize software thread allocation and memory usage. This feature allows 3 options: "Disabled", "Enabled", and "Auto". Default is "Auto".
APBDIS
This BIOS switch enables or disables Algorithm Performance Boost(APB). The processor feature of Application Power Management(APM) will allows P-states to be defined with higher frequencies but it may cause the performance jitter between the high power state and the low power state. To reduce the jitter, this feature forces the Infinity Fabric, which is the interconnect inside and outside of CPU chip, into the fixed high power state. This feature allows 3 options: "0", "1", and "Auto". Default is "Auto".
Fix SOC P-state
This BIOS switch limits CPU SOC (uncore) P-states when "APBDIS" is enabled to minimize the variance of the performance. This feature allows 4 options: "P0", "P1", "P2", "P3", and "Auto". When "Auto" is selected, CPU SOC P-states will be dynamically adjusted. Selecting a specific P-state forces the SOC into the P-state frequency. Default is "Auto".
cTDP Control
This BIOS switch allows the user can manually configure the switch of "cTDP". This feature allows 2 options: "Manual" and "Auto". "Manual" enables to customize configurable TDP. "Auto" uses the platform default TDP. Default is "Auto".
cTDP
This BIOS switch configures the maximum power that the CPU will consume, up to the platform power limit. Valid values vary by CPU model. If a value outside the valid range or the default value of "0" 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 7763225280
EPYC 7643225240
EPYC 75F3225280
EPYC 7513165200
EPYC 7453225240
EPYC 74F3225240
EPYC 7443165200
EPYC 7343165200
EPYC 72F3165200
Determinism Slider
This BIOS switch is for the determinism to control performance and allows 3 options: "Auto", "Power", and "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 BIOS switch 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 feature 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.
EDC Control
This BIOS switch allows the user can manually configure the switch of "EDC" and "EDC Platform Limit". This feature allows 2 options: "Manual" and "Auto". "Manual" enables to customize "EDC" and "EDC Platform Limit". "Auto" uses the platform default EDC. Default is "Auto".
EDC
Electrical Design Current(EDC) indicates the total maximum current capacity in Apms which can be supplied to the socket for a short time. The default value of EDC is 0 which select the platform default setting and it can be set up to 300 A. Increasing this value may increase the frequency at the cost of additional power consumption.
EDC Platform Limit
This BIOS switch limit the maximum EDC in watts which the platform can support. The default value is 0 which selects the platform default setting and it can be set up to 300 W. Increasing this value may increase the frequency at the cost of additional power consumption.
Global C-state Control
This BIOS switch controls IO based C-state generation and DF C-states. This feature allows 2 options: "Disabled", "Enabled, and "Auto". Default is "Auto"
IOMMU
This BIOS switch allows enabling or disabling of Input-Output Memory Management Unit(IOMMU) which supports the address translation and system memory access protection on DMA transfer from I/O devices in the system. This feature allows 3 options: "Auto", "Enabled", and "Disabled". Default is "Auto".
L1 Stream HW Prefetcher
This BIOS switch allows enabling or disabling of L1 Stream HW Prefetcher. This feature allows 2 options: "Disabled", "Enabled, and "Auto". Default is "Auto".
L2 Stream HW Prefetcher
This BIOS switch allows enabling or disabling of L2 Stream HW Prefetcher. This feature allows 2 options: "Disabled", "Enabled, and "Auto". Default is "Auto".
NUMA nodes per socket
This BIOS switch specifies the number of desired NUMA nodes per populated socket in the system. This feature allows 5 options: "NPS0", "NPS1", "NPS2", "NPS4", and "Auto". Default is "Auto".
Package Power Limit Control
This BIOS switch configures a per CPU Package Power Limit value applicable for all populated CPUs in the system. This feature allows 2 options: "Manual" and "Auto". "Manual" set customized configurable Package Power Limit. "Auto" uses the platform default Package Power Limit.
Package Power Limit
This BIOS switch specifies the maximum power that each CPU package may consume in the system. The actual power is limited by the maximum setting of both the "Package Power Limit" and "cTDP".
SMT Control
This BIOS switch allows enabling or disabling of symmetric multithreading on processors. This feature allows 3 options: "Disabled", "Enabled", and "Auto". When "Enabled" is set, each physical processor core operates as two logical processor cores. When "Disabled" is set, 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 "Auto".
SVM Mode
This BIOS switch is for CPU virtualization function. With SVM enabled virtual machines can be installed on the system. This feature allows 2 options: "Enabled" and "Disabled". Default is "Enabled".
xGMI Link Max Speed
This BIOS switch controls the maximum link speed of GMI (Global Memory Interface) which is the socket-to-socket interconnection. Limitting the maximum link speed can reduce xGMI power consumption and increaces the available power for cores which may improve the performance in workloads which aware NUMA. The default setting is "Auto" which selects the maximum link speed per CPU model.