SPEC CPU2017 Platform Settings for Nettrix Systems

Operating System Tuning Parameters

Used to set user limits of system-wide resources. Provides control over resources available to the shell and processes started by it. Some common ulimit commands may include:
Disabling Linux services
Certain Linux services may be disabled to minimize tasks that may consume CPU cycles.
Disabled through "service irqbalance stop". Depending on the workload involved, the irqbalance service reassigns various IRQ's to system CPUs. Though this service might help in some situations, disabling it can also help environments which need to minimize or eliminate latency to more quickly respond to events.
cpupower tool
Use the cpupower tool to read your supported CPU frequencies, and to set them. For rhel linux, to install the tool run the command "yum install cpupowerutils". You can set the cpu frequency in three modes with the command "cpupower frequency-set -g [options]", where "[options]" could be: The default governor mode is "performance".
Tuning Kernel parameters
The following Linux Kernel parameters were tuned to better optimize performance of some areas of the system:
Transparent Huge Pages (THP)
THP is an abstraction layer that automates most aspects of creating, managing, and using huge pages. THP is designed to hide much of the complexity in using huge pages from system administrators and developers, as normal huge pages must be assigned at boot time, can be difficult to manage manually, and often require significant changes to code in order to be used effectively. Transparent Hugepages increase the memory page size from 4 kilobytes to 2 megabytes. Transparent Hugepages provide 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.
Linux Huge Page settings
If you need finer control and manually set the Huge Pages you can follow the below steps: For further information about huge pages may be found in your Linux documentation file: /usr/src/linux/Documentation/vm/hugetlbpage.txt

Firmware / BIOS / Microcode Settings

Application Performance Profile:
Application Performance Profile is designed for customers who need an easy way to optimize BIOS settings according to their application scenarios. The option could be set as "Disabled", "Computing Throughput Mode", "Computing Latency Mode", "Memory Bandwidth Mode", "Energy Efficient Mode", "Java Application Mode", and "High Reliability Mode". Default = "High Reliability Mode".
C-states reduce CPU idle power. There are three options in this mode: "Legacy","Autonomous", and "Disable". Default is "Disable".
C1 Enhanced Mode:
Enabling C1E (C1 enhanced) state can save power by halting CPU cores that are idle. Default is "Enable".
Turbo Mode:
Enabling turbo mode can boost the overall CPU performance when all CPU cores are not being fully utilized. A CPU core can run above its rated frequency for a short perios of time when it is in turbo mode. Default is "Enable".
Enabling Hyper-Threading let operating system addresses two virtual or logical cores for a physical presented core. Workloads can be shared between virtual or logical cores when possible. The main function of hyper-threading is to increase the number of independent instructions in the pipeline for using the processor resources more efficiently. Default is "Enabled".
Hardware P-states:
This setting allows the user to select between OS and hardware-controlled P-states. Selecting Native Mode allows the OS to choose a P-state. Selecting Out of Band Mode allows the hardware to autonomously choose a P-state without OS guidance. Selecting Native Mode with No Legacy Support functions as Native Mode with no support for older hardware. Default is "Disable".
Per Core P-state:
When per-core P-states are enabled, each physical CPU core can operate at separate frequencies. If disabled, all cores in a package will operate at the highest resolved frequency of all active threads. Default is Enable.
Sub-NUMA Cluster (SNC):
SNC breaks up the last level cache (LLC) into disjoint clusters based on address range, with each cluster bound to a subset of the memory controllers in the system. SNC improves average latency to the LLC and memory. SNC is a replacement for the cluster on die (COD) feature found in previous processor families. For a multi-socketed system, all SNC clusters are mapped to unique NUMA domains. (See also IMC interleaving.) Values for this BIOS option can be: Default is "Disabled".
XPT Prefetch
XPT prefetch is a mechanism that enables a read request that is being sent to the last level cache to speculatively issue a copy of that read to the memory controller prefetching. This can be one of the following:
KTI Prefetch
KTI prefetch is a mechanism to get the memory read started early on a DDR bus. This can be one of the following: The default setting is "Disabled".
UPI Prefetcher
UPI prefetch is a mechanism to get the memroy read started early on DDR bus. The UPI receive path will spawn a memory read to the memory controller prefetcher. Default is Enabled.
Patrol Scrub:
Patrol Scrub is a memory RAS feature which runs a background memory scrub against all DIMMs. Can negatively impact performance. This option allows for correction of soft memory errors. Over the length of system runtime, the risk of producing multi-bit and uncorrected errors is reduced with this option. Values for this BIOS setting can be: Default is Enabled.
DCU Streamer Prefetcher:
DCU (Level 1 Data Cache) streamer prefetcher is an L1 data cache prefetcher. Lightly threaded applications and some benchmarks can benefit from having the DCU streamer prefetcher enabled. Default setting is Enable.
Hardware Prefethcer:
When this option is enable, a dedicated hardware mechanism in the processor is supported to watch the stream of instructions or data being requested by the executing program, recognize the next few elements that the program might need based on this stream and prefetch into the processor's cache. The program with good instruction and data locality will benefit from this feature when this option is enable. Default is enable.
Trusted Execution Technology:
Enable Intel Trusted Execution Technology (Intel TXT). Default is disable.
Page Policy:
Adaptive Open Page Policy can improve performance for applications with a highly localized memory access pattern; Closed Page Policy can benifit applications that access memory more randomly. The default is "Auto".
LLC Dead Line Allocation:
If the Dead Line LLC Alloc feature is disabled, dead lines will always be dropped and will never fill into the LLC. This can help save space in the LLC and prevent the LLC from evicting useful data. However, if the Dead Line LLC Alloc feature is enabled, the LLC can opportunistically fill dead lines into the LLC if there is free space available. The default is enable.
Stale AtoS
Stale AtoS is the transition of a directory line state. The inmemory directory has three states: I, A, and S. I (invalid) state means the data is clean and does not exist in any other socket's cache. The A (snoopAll) state means the data may exist in another socket in exclusive or modified state. S (Shared) state means the data is clean and may be shared across one or more socket's caches. When doing a read to memory, if the directory line is in the A state, we must snoop all the other sockets because another socket may have the line in modified state. If this is the case,the snoop will return the modified data. However, it may be the case that a line is read in A state and all the snoops come back a miss. This can happen if another socket read the line earlier and then silently dropped it from its cache without modifying it. Values for this BIOS option can be: Default is Auto.
Cooling Policy
The feature to configure "Cooling Policy" option is provided on BMC webpage. This option provides 4 choices: "Balance Mode", "Performance Mode", "Silent Mode" and "Manual Mode" and default is "Balance Mode".