SPEC CPU2006/SPEC CPU2017 Platform Settings for HPE ProLiant Intel-based systems

Operating System Tuning Parameters

OS Tuning

ulimit:

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:

• ulimit -s [n | unlimited]: Set the stack size to n kbytes, or unlimited to allow the stack size to grow without limit.
• ulimit -l (number): Set the maximum size that can be locked into memory.

Disabling Linux services:

Certain Linux services may be disabled to minimize tasks that may consume CPU cycles.

irqbalance:

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.

Performance Governors (Linux):

In-kernel CPU frequency governors are pre-configured power schemes for the CPU. The CPUfreq governors use P-states to change frequencies and lower power consumption. The dynamic governors can switch between CPU frequencies, based on CPU utilization to allow for power savings while not sacrificing performance.

Other options beside a generic performance governor can be set, such as the perf-bias:

--perf-bias, -b

On supported Intel processors, this option sets a register which allows the cpupower utility (or other software/firmware) to set a policy that controls the relative importance of performance versus energy savings to the processor. The range of valid numbers is 0-15, where 0 is maximum performance and 15 is maximum energy efficiency.

The processor uses this information in model-specific ways when it must select trade-offs between performance and energy efficiency. This policy hint does not supersede Processor Performance states (P-states) or CPU Idle power states (C-states), but allows software to have influence where it would otherwise be unable to express a preference.

On many Linux systems one can set the perf-bias for all CPUs through the cpupower utility with one of the following commands:

• "cpupower -c all set -b 0"
• "cpupower -c all set --perf-bias 0"
• "cpupower set -b 0"

Tuning Kernel parameters:

The following Linux Kernel parameters were tuned to better optimize performance of some areas of the system:

• dirty_background_ratio: Set through "echo 40 > /proc/sys/vm/dirty_background_ratio". This setting can help Linux disk caching and performance by setting the percentage of system memory that can be filled with dirty pages.
• dirty_ratio: Set through "echo 40 > /proc/sys/vm/dirty_ratio". This setting is the absolute maximum amount of system memory that can be filled with dirty pages before everything must get committed to disk.
• swappiness: The swappiness value can range from 1 to 100. A value of 100 will cause the kernel to swap out inactive processes frequently in favor of file system performance, resulting in large disk cache sizes. A value of 1 tells the kernel to only swap processes to disk if absolutely necessary. This can be set through a command like "echo 1 > /proc/sys/vm/swappiness"
• numa_balancing: Disabled through "echo 0 > /proc/sys/kernel/numa_balancing". This feature will automatically migrate data on demand so memory nodes are aligned to the local CPU that is accessing data. Depending on the workload involved, enabling this can boost the performance if the workload performs well on NUMA hardware. If the workload is statically set to balance between nodes, then this service may not provide a benefit.
• Zone Reclaim Mode: Zone reclaim allows the reclaiming of pages from a zone if the number of free pages falls below a watermark even if other zones still have enough pages available. Reclaiming a page can be more beneficial than taking the performance penalties that are associated with allocating a page on a remote zone, especially for NUMA machines. To tell the kernel to free local node memory rather than grabbing free memory from remote nodes, use a command like "echo 1 > /proc/sys/vm/zone_reclaim_mode"

tuned-adm:

The tuned-adm is a tool allows selecting/applying different tuning profiles (such as throughput-performance, latency-performance, server-powersave, etc) supported in many Linux distributions.

• Use “tuned-adm list” to list all available profiles
• Use “tuned-adm active” to list the currently configured profile
• Use “tuned-adm profile "profile-name"” to apply or set a specific profile
• Refer to the OS documentation for more details on the tuned profile.

Transparent Huge Pages (THP):

Transparent Hugepages can be used to increase the memory page size from 4 kilobytes to 2 megabytes. THP 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.

• Examples
• echo always >/sys/kernel/mm/transparent_hugepage/enabled
• echo madvise >/sys/kernel/mm/transparent_hugepage/enabled
• echo never >/sys/kernel/mm/transparent_hugepage/enabled
• Refer to the OS documentation for more details on THP.

Firmware / BIOS / Microcode Settings

Firmware Settings

One or more of the following settings may have been set. If so, the "Platform Notes" section of the report will say so; and you can read below to find out more about what these settings mean.

Intel Hyper-Threading (Default = Enabled):

This feature allows enabling or disabling of logical processor cores on processors supporting Intel Hyper-Threading (HT). When enabled, each physical processor core operates as two logical processor cores. When disabled, each physical core operates as only one logical processor core. Enabling this option can improve overall performance for applications that benefit from a higher processor core count.

Intel Virtualization Technology (Intel VT, VT-x) (Default = Enabled):

When enabled, a hypervisor or operating system supporting this option can use hardware capabilities provided by Intel VT. Some hypervisors require that you enable Intel VT. You can leave this set to enabled even if you are not using a hypervisor or an operating system that uses this option. With default BIOS settings as shipped with most systems, the default state for this setting is Enabled. However, this setting can change it's default setting depending on the Workload Profile that is selected, or what Workload Profile is default for a certain system.

VT-d (Intel VT-d) (Default = Enabled):

If enabled, a hypervisor or operating system supporting this option can use hardware capabilities provided by Intel VT for Directed I/O. You can leave this set to enabled even if you are not using a hypervisor or an operating system that uses this option. With default BIOS settings as shipped with most systems, the default state for this setting is Enabled. However, this setting can change it's default setting depending on the Workload Profile that is selected, or what Workload Profile is default for a certain system.

Processor x2APIC Support (Default = Enabled):

If enabled, x2APIC support enables operating system to run more efficiently on high core count configurations. It also optimizes interrupt distribution in virtualized environments. Setting this option to Enabled is recommended for most cases. When enabled, the operating system can optionally enable x2APCI support when it loads. Older hypervisors and operating systems might have issues with optional x2APIC support, therefore disabling x2APIC could be necessary to address these issues. Setting this option to Enabled also forces Intel VT-D to be enabled.

SR-IOV (Default = Enabled):

If enabled, SR-IOV support enables a hypervisor to create virtual instances of PCI-express device, potentially increasing performance. If enabled, the BIOS allocates additional resources to PCI-express devices. You can leave this option set to Enabled even if you are not using a hypervisor. With default BIOS settings as shipped with most systems, the default state for this setting is Enabled. However, this setting can change it's default setting depending on the Workload Profile that is selected, or what Workload Profile is default for a certain system.

Thermal Configuration (Default = Optimal Cooling):

This feature allows the user to select the fan cooling solution for the system. Values for this BIOS option can be:

• Optimal Cooling: Provides the most efficient solution by configuring fan speeds to the minimum required to provide adequate cooling.
• Increased Cooling: Will run fans at higher speeds to provide additional cooling. Increased Cooling should be selected when non-HPE storage controllers are cabled to the embedded hard drive cage, or if the system is experiencing thermal issues that cannot be resolved in another manner.
• Maximum Cooling: Will provide the maximum cooling available for this platform.

Last Level Cache (LLC) Dead Line Allocation (Default = Enabled):

In the Xeon Scalable processor cache scheme, mid-level cache (MLC) evictions are filled into the last level cache (LLC). If a line is evicted from the MLC to the LLC, the core can flag the evicted MLC lines as "dead". This means that the lines are not likely to be read again. This option allows dead lines to be dropped and never fill the LLC if the option is disabled. Values for this BIOS option can be:

• Disabled: Disabling this option can save space in the LLC by never filling dead lines into the LLC. This can prevent useful data from being evicted.
• Enabled: Opportunistically fill dead lines in LLC, if space is available.

Enhanced Processor Performance Profile (Default = Disabled):

Use this option to select a pre-defined enhanced processor performance profiles. Based upon the selection, this feature will adjust the processor settings for improved performance, but may result in higher power consumption. Values for this BIOS option can be:

• Disabled: No adjustments are made to the system for performance with no change in power consumption.
• Conservative: This profile will apply minimal adjustments, but still allow for some improved performance and higher power consumption.
• Moderate: This profile will apply more adjustments than Conservative profile for improving performance, but may result in higher power consumption than Conservative profile.
• Aggressive: The aggressive profile can provide the maximum improvement in performance, but may result in higher power consumption as compared to Moderate and Conservative profiles.

Stale A to S (Default = Disabled):

The in-memory directory has three states: invalid (I), snoopAll (A), and shared (S). Invalid (I) state means the data is clean and does not exist in any other socket`s cache. The snoopAll (A) state means the data may exist in another socket in exclusive or modified state. Shared (S) 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:

• Disabled: Disabling this option allows the feature to process memory directories as described above.
• Enabled: In the situation where a line in A state returns only snoop misses, the line will transition to S state. That way, subsequent reads to the line will encounter it in S state and not have to snoop, saving latency and snoop bandwidth.

Stale A to S may be beneficial in a workload where there are many cross-socket reads.

Last Level Cache (LLC) Prefetch (Default = Disabled):

This option configures the processor Last Level Cache (LLC) prefetch feature as a result of the non-inclusive cache architecture. The LLC prefetcher exists on top of other prefetchers that that can prefetch data in the core data cache unit (DCU) and mid-level cache(MLC). In some cases, setting this option to disabled can improve performance. Typically, setting this option to Enabled provides better performance. Values for this BIOS option can be:

• Disabled: Disabling this option can forces data to fill the MLC before prefetching data to the LLC.
• Enabled: Giving the core prefetcher the ability to prefetch data directly to the LLC without filling the MLC.

NUMA Group Size Optimization (Default = Clustered):

This feature allows the user to configure how the BIOS reports the size of a NUMA node (number of logical processors), which assists the Operating System in grouping processors for application use (referred to as Kgroups). Values for this BIOS option can be:

• Clustered: Might provide better performance for some workloads due to optimizing the resulting groups along NUMA boundaries.
• Flat: Might provide better performance for some workloads that cannot take advantage of processors spanning multiple groups. This setting would be necessary to help this class of applications utilize more logical processors.

Sub-NUMA Clustering (SNC) (Default = Enabled):

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. Values for this BIOS option can be:

• Disabled: The LLC is treated as one cluster when this option is disabled
• Enable SNC2(2-clusters): SNC2 partitions LLC into two NUMA domains containing equal number of cores, equal number of LLC slices, equal amount of socket address space and each node bound to a subset of the memory controller on the socket.
• Enable SNC4(4-clusters): SNC4 is an extension of SNC2 where it divides the die into four NUMA domains and equally divides the memory range between the domains. Both SNC2 and SNC4 trades-off peak IO bandwidth for best core to memory latencies.

DCU Stream Prefetcher (Default = Enabled):

In most environments, leave the option enabled for optimal performance. With certain workloads, disabling it might provide a performance benefit. Do so only after performing application benchmarking to verify improved performance in a particular environment. Values for this BIOS option can be:

• Enabled: Once enabled, the DCU streamer prefetcher will detect multiple loads from the same cache line within a time limit and prefetches data into L1 cache.
• Disabled: Disabling the DCU streamer prefetcher will not fetch data from L2 or main memory into L1 cache to speed up data access.

Uncore Frequency Scaling (Default = Auto):

This option controls the frequency scaling of the processor`s internal buses (the uncore). Values for this BIOS option can be:

• Auto: Enabled the processor to dynamically change frequencies based on the workload.
• Maximum: Enables tuning for latency.
• Minimum: Enables tuning for power consumption.

Workload Profile (Default = General Power Efficient Compute):

This option allows a user to choose one workload profile that best fits the user`s needs. The workload profiles control many power and performance settings that are relevant to general workload areas. Values for this BIOS option can be:

• General Power Efficient Compute, General Peak Frequency Compute, General Throughput Compute, Virtualization - Power Efficient, Virtualization - Max Performance, Low Latency, Mission Critical, Transaction Application Processing, High Performance Compute (HPC), Decision Support, Graphic Processing, I/O Throughput, or Custom.
• Setting the Workload Profile to any option not named Custom allows the server to automatically configure various BIOS settings. These BIOS settings control many power and performance settings that are relevant to general workload areas that fit the profile name.
• Setting the Workload Profile to Custom allows a user to set any BIOS setting to any supported setting. Choosing Custom after selecting an initial profile does not change the settings controlled by the profile previously selected without user intervention.
• Further technical description about what settings a Workload Profile changes and the types of workloads that a profile may be suitable for can be found through the HPE UEFI Workload-based Performance and Tuning Guide - https://support.hpe.com/hpsc/doc/public/display?docId=a00016408en_us

Minimum Processor Idle Power Core C-State (Default = C6 State):

This option can only be configured if the Workload Profile is set to Custom, or this option is not a dependent value for the Workload Profile. This feature selects the processor's lowest idle power state (C-state) that the operating system uses. The higher the C-state, the lower the power usage of that idle state (C6 is the lowest power idle state supported by the processor). Values for this setting can be:

• C6 State: While in C6, the core PLLs are turned off, the core caches are flushed and the core state is saved to the Last Level Cache. Power Gates are used to reduce power consumption to close to zero. C6 is considered for an inactive core.
• C1E State: C1E is defined as the enhanced halt state. While in C1E no instructions are being executed. C1E is considered for an active core.
• No C-states: No C-states is defined as C0, which is defined as the active state. While in C0, instructions are being executed by the core.

Minimum Processor Idle Power Package C-State (Default = Package C6 (retention) State):

This option can only be configured if the Workload Profile is set to Custom, or this option is not a dependent value for the Workload Profile. This feature selects the processor's lowest idle package power state (C-state) that is enabled. The processor will automatically transition into the package C-states based on the Core C-states, in which cores on the processor have transitioned. The higher the package C-state, the lower the power usage of that idle package state. Package C6 (retention) is the lowest power idle package state supported by the processor). Values for this setting can be:

• Package C6 (retention) State: All cores have saved their architectural state and have had their core voltages reduced to zero volts. The LLC retains context, but no accesses can be made to the LLC in this state, the cores must break out to the internal state package C2 for snoops to occur.
• Package C6 (non-retention) State: All cores have saved their architectural state and have had their core voltages reduced to zero volts. The LLC does not retain context, and no accesses can be made to the LLC in this state, the cores must break out to the internal state package C2 for snoops to occur.
• No Package State: All cores are in an active state and have not entered any power saving state.

Energy/Performance Bias (Default = Balanced Performance):

This option can only be configured if the Workload Profile is set to Custom, or this option is not a dependent value for the Workload Profile. This option configures several processor subsystems to optimize the processor's performance and power usage. Values for this BIOS setting can be:

• Balanced Performance: Provides optimum performance efficiency and is recommended for most environments.
• Maximum Performance: Should be used for environments that require the highest performance and lowest latency but are not sensitive to power consumption.
• Balanced Power: Similar to Balanced Performance but this option prioritizes more power savings at the sacrifice of performance.
• Power Savings Mode: Should only be used in environments that are power sensitive and are willing to accept reduced performance.

Energy Efficient Turbo (Default = Enabled):

This option controls whether the processor uses an energy efficiency based policy when engaging turbo range frequencies. This option is only applicable when Turbo Mode is enabled. Values for this BIOS setting can be: Enabled or Disabled.

Memory Patrol Scrubbing (Default = Enabled):

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:

• Enabled: Correction of soft memory errors can occur during runtime.
• Disabled: Soft memory error correction is turned off during runtime.

HW Prefetcher (Default = Enabled):

Use this option to disable the processor HW Prefetch feature. In some cases, setting this option to disabled can improve performance. Typically, setting this option to enabled provides better performance. Only disable this option after performing application benchmarking to verify improved performance in the environment. The HW Prefetcher fetches streams of data and instruction from the memory into the second-level (L2) cache if it determines this data is likely to be required in the near future. The prefetcher is capable of handling multiple streams in either the forward or backward direction. The HW Prefetcher is triggered when successive cache misses occur in the last-level cache and a stride in the access pattern is detected, such as in the case of loop iterations that access array elements. The prefetching occurs up to a page boundary. This option can reduce the latency associated with memory reads. Values for this BIOS setting can be enabled or disabled.

Adjacent Sector Prefetch (Default = Enabled):

Use this option to disable the processor Adjacent Sector Prefetch feature. In some cases, setting this option to disabled can improve performance. Typically, setting this option to enabled provides better performance. Only disable this option after performing application benchmarking to verify improved performance in the environment. The Adjacent Sector Prefetch retrieves both sectors of a cache line when it requires data that isn't currently in the cache. When disabled, the processor will only fetch the sector of the cache line that includes the requested data. Values for this BIOS setting can be enabled or disabled.

Intel UPI Link Enablement (Default = Auto):

Use this option to configure the UPI topology to use fewer links between processors, when available. Changing from the default can reduce UPI bandwidth performance in exchange for less power consumption. Values for this BIOS setting can be: Auto and Single Link Operation.

Intel UPI Link Power Management (Default = Enabled):

Use this option to place the Quick Path Interconnect (UPI) links into a low power state when the links are not being used. This lowers power usage with minimal effect on performance. You can only configure this option if two or more CPUs are present and the Workload Profile is set to Custom. Values for this BIOS setting can be: enabled and disabled.

Intel UPI Link Frequency (Default = Auto):

Use this option to set the UPI Link frequency to a lower speed. Running at a lower frequency can reduce power consumption, but can also affect system performance. You can only configure this option if two or more CPUs are present and the Workload Profile is set to Custom. Values for this BIOS setting can be: Auto and Min UPI Speed.

Direct to UPI (D2K) (Default = Auto):

Provides a performance benefit in multiprocessor configured systems that rely on the UPI bus for memory or I/O accesses. This is due to the Last Level Cache (LLC) reducing the latency due to cache misses. Values for this BIOS setting can be:

• Auto: Default value. If this is selected, this option will be set to either Enabled or Disabled by other settings.
• Enabled: Allows the memory controller to send data directly to the Intel UPI.
• Disabled: Allows the memory controller to send data via its local caching agent to the Intel UPI.

Advanced Memory Protection (Default = Advanced ECC Support):

Use this option to configure additional memory protection with ECC (Error Checking and Correcting). Options and support vary per system and configuration. Values for this BIOS setting can be:

• Advanced ECC Support: Keeps all installed memory available for use while still protecting the system against all single-bit failures and certain multi-bit failures.
• Online Spare with Advanced ECC Support: Enables a system to automatically map out a group of memory that is detected to be at an increased risk of receiving uncorrected memory errors based on an advanced analysis of corrected memory errors. The mapped out memory is automatically replaced by a spare group of memory without interrupting the system.
• Mirrored Memory with Advanced ECC Support: Provides the maximum protection against uncorrected memory errors that might otherwise result in a system failure.
• Fast Fault Tolerant Advanced Double Device Data Correction (ADDDC): Enables the system to correct memory errors and continue to operate in cases of multiple DRAM device failures on a DIMM. This provides protection against uncorrectable memory errors beyond what is available with Advanced ECC.

Intel DMI Link Frequency (Default = Auto):

Use this option to set the DMI Link frequency to a lower frequency between the processor and PCH. Running at a lower frequency can reduce power consumption, but can also affect system performance. Values for this BIOS setting can be:

• Auto: This option will enable the system to run with the highest supported DMI link speed.
• Gen1 Speed: This option will enable the system to run with Gen1 speed of 2.5 Gbps
• Gen2 Speed: This option will enable the system to run with Gen2 speed of 5.0 Gbps

Dead Block Predictor (Default = Disabled):

This feature could benefit multi-threaded workloads based upon improved prediction of cache line evictions. Values for this BIOS setting can be Disabled or Enabled.

Last modified Dec 7, 2022.