SPEC CPU2017 Platform Settings for GIGA-BYTE

Operating System Tuning Parameters

kernel.randomize_va_space (ASLR)
This setting can be used to select the type of process address space randomization. Defaults differ based on whether the architecture supports ASLR, whether the kernel was built with the CONFIG_COMPAT_BRK option or not, or the kernel boot options used.
Possible settings: Disabling ASLR can make process execution more deterministic and runtimes more consistent. For more information see the randomize_va_space entry in the Linux sysctl documentation.
Transparent Hugepages (THP)
THP is an abstraction layer that automates most aspects of creating, managing, and using huge pages. It is designed to hide much of the complexity in using huge pages from system administrators and developers. Huge pages increase the memory page size from 4 kilobytes to 2 megabytes. This provides significant performance advantages on systems with highly contended resources and large memory workloads. If memory utilization is too high or memory is badly fragmented which prevents hugepages being allocated, the kernel will assign smaller 4k pages instead. Most recent Linux OS releases have THP enabled by default.
THP usage is controlled by the sysfs setting /sys/kernel/mm/transparent_hugepage/enabled. Possible values: THP creation is controlled by the sysfs setting /sys/kernel/mm/transparent_hugepage/defrag. Possible values: An application that "always" requests THP often can benefit from waiting for an allocation until those huge pages can be assembled.
For more information see the Linux transparent hugepage documentation.

Firmware / BIOS / Microcode Settings

Determinism Slider: (Default = Power)
Selects the determinism mode for the CPU:
cTDP Control:(Default = 280)
Configures the maximum power that the CPU will consume, up to the platform power limit (PPT). 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 (PPT), which may be less than the cTDP setting.
ModelMinimum cTDPMaximum cTDP
EPYC 7763225280
EPYC 7713225240
Package Power Limit (PPT) Control:(Default = 280)
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.
ModelMinimum cTDPMaximum cTDP
EPYC 7763225280
EPYC 7713225240
NUMA nodes per socket:(Default = NPS4)
Specifies the number of desired NUMA nodes per populated socket in the system:
SMT Mode: (Default = Enabled)
Can be used to disable symmetric multithreading. To re-enable SMT, a POWER CYCLE is needed after selecting the 'Auto' option. WARNING - S3 is NOT SUPPORTED on systems where SMT is disabled.
IOMMU: (Default = Enabled)
Enable: Enables the I/O Memory Management Unit (IOMMU), which extends the AMD64 system architecture by adding support for address translation and system memory access protection on DMA transfers from peripheral devices.
4-link xGMI max speed:(Default = 16Gbps)
xGMI (Global Memory Interface) is the Socket SP3 processor socket-to-socket interconnection topology comprised of four x16 links. Each x16 link is comprised of 16 lanes. Each lane is comprised of two unidirectional differential signals. Since xGMI is the interconnection between processor sockets, these xGMI settings are not applicable for 1S platforms. NUMA-unaware workloads may need maximum xGMI bandwidth/speed while other compute efficient platforms may need to minimize xGMI power. The xGMI speed can be lowered, lane width can be reduced from x16 to x8 (or x2), or an xGMI link can be disabled if power consumption is too high.
The default value for this option on Milan platforms is "Auto" which corresponds to "16Gbps". On platforms that support higher speeds, it can be raised to increase performance on workloads that benefit from higher cross-socket bandwidth at the cost of some additional power consumption.