CPU2017 Flag Description
Dell Inc. PowerEdge R7425 (AMD EPYC 7261, 2.50GHz)

This result has been formatted using multiple flags files. The "default header section" from each of them appears next.


Default header section from gcc

GNU Compiler Collection Flags

Flag descriptions for GCC, the GNU Compiler Collection

Note: The GNU Compiler Collection provides a wide array of compiler options, described in detail and readily available at https://gcc.gnu.org/onlinedocs/gcc/Option-Index.html#Option-Index and https://gcc.gnu.org/onlinedocs/gfortran/. This SPEC CPU flags file contains excerpts from and brief summaries of portions of that documentation.

SPEC's modifications are:
Copyright (C) 2006-2017 Standard Performance Evaluation Corporation

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being "Funding Free Software", the Front-Cover Texts being (a) (see below), and with the Back-Cover Texts being (b) (see below). A copy of the license is included in your SPEC CPU kit at $SPEC/Docs/licenses/FDL.v1.3 and on the web at http://www.spec.org/cpu2017/Docs/licenses/FDL.v1.3. A copy of "Funding Free Software" is on your SPEC CPU kit at $SPEC/Docs/licenses/FundingFreeSW and on the web at http://www.spec.org/cpu2017/Docs/licenses/FundingFreeSW.

(a) The FSF's Front-Cover Text is:

A GNU Manual

(b) The FSF's Back-Cover Text is:

You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.


Default header section from aocc130-flags-revA2

AMD Optimizing C/C++ Compiler Suite Version 1.3.0 SPEC CPU2017 Flag Description

Compilers: AMD Optimizing C/C++ Compiler Suite 1.3.0


Base Compiler Invocation

C benchmarks

C++ benchmarks

Fortran benchmarks

Benchmarks using both Fortran and C

Benchmarks using both C and C++

Benchmarks using Fortran, C, and C++


Peak Compiler Invocation

C benchmarks

C++ benchmarks

Fortran benchmarks

Benchmarks using both Fortran and C

Benchmarks using both C and C++

Benchmarks using Fortran, C, and C++


Base Portability Flags

503.bwaves_r

507.cactuBSSN_r

508.namd_r

510.parest_r

511.povray_r

519.lbm_r

521.wrf_r

526.blender_r

527.cam4_r

538.imagick_r

544.nab_r

549.fotonik3d_r

554.roms_r


Peak Portability Flags

503.bwaves_r

507.cactuBSSN_r

508.namd_r

510.parest_r

511.povray_r

519.lbm_r

521.wrf_r

526.blender_r

527.cam4_r

538.imagick_r

544.nab_r

549.fotonik3d_r

554.roms_r


Base Optimization Flags

C benchmarks

C++ benchmarks

Fortran benchmarks

Benchmarks using both Fortran and C

Benchmarks using both C and C++

Benchmarks using Fortran, C, and C++


Peak Optimization Flags

C benchmarks

519.lbm_r

538.imagick_r

544.nab_r

C++ benchmarks

508.namd_r

510.parest_r

Fortran benchmarks

503.bwaves_r

549.fotonik3d_r

554.roms_r

Benchmarks using both Fortran and C

521.wrf_r

527.cam4_r

Benchmarks using both C and C++

Benchmarks using Fortran, C, and C++


Implicitly Included Flags

This section contains descriptions of flags that were included implicitly by other flags, but which do not have a permanent home at SPEC.


Commands and Options Used to Submit Benchmark Runs

This result has been formatted using multiple flags files. The "submit command" from each of them appears next.


Submit command from gcc

GNU Compiler Collection Flags

SPECrate runs might use one of these methods to bind processes to specific processors, depending on the config file.


Submit command from aocc130-flags-revA2

AMD Optimizing C/C++ Compiler Suite Version 1.3.0 SPEC CPU2017 Flag Description

Using numactl to bind processes and memory to cores

For multi-copy runs or single copy runs on systems with multiple sockets, it is advantageous to bind a process to a particular core. Otherwise, the OS may arbitrarily move your process from one core to another. This can affect performance. To help, SPEC allows the use of a "submit" command where users can specify a utility to use to bind processes. We have found the utility 'numactl' to be the best choice.

numactl runs processes with a specific NUMA scheduling or memory placement policy. The policy is set for a command and inherited by all of its children. The numactl flag "--physcpubind" specifies which core(s) to bind the process. "-l" instructs numactl to keep a process's memory on the local node while "-m" specifies which node(s) to place a process's memory. For full details on using numactl, please refer to your Linux documentation, 'man numactl'

Note that some older versions of numactl incorrectly interpret application arguments as its own. For example, with the command "numactl --physcpubind=0 -l a.out -m a", numactl will interpret a.out's "-m" option as its own "-m" option. To work around this problem, we put the command to be run in a shell script and then run the shell script using numactl. For example: "echo 'a.out -m a' > run.sh ; numactl --physcpubind=0 bash run.sh"


Commands and Options Used for Feedback-Directed Optimization

No special commands are needed for feedback-directed optimization, other than the compiler profile  flags.


Shell, Environment, and Other Software Settings

This result has been formatted using multiple flags files. The "sw environment" from each of them appears next.


Sw environment from gcc

GNU Compiler Collection Flags

One or more of the following may have been used in the run. If so, it will be listed in the notes sections. Here is a brief guide to understanding them:


Sw environment from aocc130-flags-revA2

AMD Optimizing C/C++ Compiler Suite Version 1.3.0 SPEC CPU2017 Flag Description

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. Most recent Linux OS releases have THP enabled by default.

Linux Huge Page settings

If you need finer control you can manually set huge pages using the following steps:

Note that further information about huge pages may be found in the Linux kernel documentation file hugetlbpage.txt.

ulimit -s <n>

Sets the stack size to n kbytes, or unlimited to allow the stack size to grow without limit.

ulimit -l <n>

Sets the maximum size of memory that may be locked into physical memory.

cpupower frequency-set -r -g performance (on Ubuntu, SLES, RHEL)

Sets the CPU governor to "performance" to enable the highest supported performance state for all cores.

powersave -f (on SuSE)

Makes the powersave daemon set the CPUs to the highest supported frequency.

/etc/init.d/cpuspeed stop (on Red Hat)

Disables the cpu frequency scaling program in order to set the CPUs to the highest supported frequency.

OMP_NUM_THREADS

Sets the maximum number of OpenMP parallel threads applications based on OpenMP may use.

LD_LIBRARY_PATH

An environment variable that indicates the location in the filesystem of bundled libraries to use when running the benchmark binaries.

kernel/randomize_va_space

This option can be used to select the type of process address space randomization that is used in the system, for architectures that support this feature.

MALLOC_CONF

An environment variable set to tune the jemalloc allocation strategy during the execution of the binaries. This environment variable setting is not needed when building the binaries on the system under test.


Firmware / BIOS / Microcode Settings

C States:

C States allow the processor to enter lower power states when idle. When set to Enabled (OS controlled) or when set to Autonomous (if Hardware controlled is supported), the processor can operate in all available Power States to save power, but my increase memory latency and frequency jitter.

Determinism Slider:

It controls whether BIOS will enable determinism to control performance. Performance: BIOS will enable 100% deterministic performance control. Power: BIOS will not enable deterministic performance control.

Adaptive Double DRAM Device Correction (ADDDC):

When Adaptive Double DRAM Device Correction (ADDDC) is enabled, failing DRAM’s are dynamically mapped out. When set to enabled, it can have some impact to system performance under certain workloads. This feature is applicable for x4 DIMMs only.

DCU Streamer Prefetcher:

Enables or disables Data Cache Unit (DCU) Streamer Prefetcher. This setting can affect performance, depending on the application running on the server. Recommended for High Performance Computing applications.

Memory Frequency:

Governs the BIOS memory frequency. The variables that govern maximum memory frequency include the maximum rated frequency of the DIMMs, the DIMMs per channel population, the processor choice, and this BIOS option. Additional power savings can be achieved by reducing the memory frequency, at the expense of reduced performance.

Turbo Boost:

Governs the Boost Technology. This feature allows teh processor cores to be automatically clocked up in frequency beyond the advertised processor speed. The amount of increased frequency (or 'turbo upside') one can expect from an EPYC processor depends on the fewer cores being exercised with work the higher the potential turbo upside. The potential drawback for Boost are mainly centered on increased power consumption and possible frequency jitter that can affect a small minority of latency-sensitive environments.

C1E:

When set to Enabled, the processor is allowed to switch to minimum performance state when idle.

CPU Interconnect Bus Link Power Management:

When Enabled, CPU interconnect bus link power management can reduce overall system power a bit while slightly reducing system performance.

CPU Performance:

Maximum Performance is typically selected for performance-centric workloads where it is acceptable to consume additional power to achieve the highest possible performance for the computing environment. This mode drives processor frequency to the maximum across all cores (although idled cores can still be frequency reduced by C-state enforcement through BIOS or OS mechanisms if enabled). This mode also offers the lowest latency of the CPU Power Management Mode options, so is always preferred.

Energy Efficient Policy:

The CPU uses the setting to manipulate the internal behavior of the processor and determines whether to target higher performance or better power savings. The possible settings are: Performance, Balanced Performance, Balanced Energy, Energy Efficient.

Energy Efficient Turbo:

Permits Energy Efficient Turbo to be Enabled or Disabled.
Energy Efficient Turbo (EET) is a mode of operation where a processor's core frequency is adjusted within the turbo range based on workload.

Logical Processor:

Each processor core supports up to two logical processors. When set to Enabled, the BIOS reports all logical processors. When set to Disabled, the BIOS only reports one logical processor per core. Generally, higher processor count results in increased performance for most multi-threaded workloads and the recommendation is to keep this enabled. However, there are some floating point/scientific workloads, including HPC workloads, where disabling this feature may result in higher performance.

Memory Patrol Scrub:

Patrol Scrubbing searches the memory for errors and repairs correctable errors to prevent the accumulation of memory errors. When set to Disabled, no patrol scrubbing will occur. When set to Standard Mode, the entire memory array will be scrubbed once in a 24 hour period. When set to Extended Mode, the entire memory array will be scrubbed more frequently to further increase system reliability.

Memory Refresh Rate:

The memory controller will periodically refresh the data in memory. The frequency at which memory is normally refreshed is referred to as 1X refresh rate. When memory modules are operating at a higher than normal temperature or to further increase system reliability, the refresh rate can be set to 2X, but may have a negative impact on memory subsystem performance under some circumstances.

PCI ASPM L1 Link Power Management:

When Enabled, PCIe Advanced State Power Management (ASPM) can reduce overall system power a bit while slightly reducing system performance.

NOTE: Some devices may not perform properly (they may hang or cause the system to hang) when ASPM is enabled, for this reason L1 will only be enabled for validated qualified cards.

System Profile:

When set to Custom, you can change setting of each option. Under Custom mode when C States is enabled, Monitor/Mwait should also be Enabled.

Monitor/Mwait:

Specifies whether Monitor/Mwait instructions are enabled. Monitor/Mwait is only active when C States is set to Disabled.

Sub NUMA Cluster:

When Enabled, Sub NUMA Clustering (SNC) is a feature for breaking up the LLC into disjoint clusters based on address range, with each cluster bound to a subset of the memory controllers in the system. It improves average latency to the LLC.

Uncore Frequency:

Selects the Processor Uncore Frequency.
Dynamic mode allows processor to optimize power resources across the cores and uncore during runtime. The optimization of the uncore frequency to either save power or optimize performance is influenced by the setting of the Energy Efficient Policy.

Virtualization technology:

When set to Enabled, the BIOS will enable processor Virtualization features and provide the virtualization support to the Operating System (OS) through the DMAR table. In general, only virtualized environments such as VMware(r) ESX (tm), Microsoft Hyper-V(r) , Red Hat(r) KVM, and other virtualized operating systems will take advantage of these features. Disabling this feature is not known to significantly alter the performance or power characteristics of the system, so leaving this option Enabled is advised for most cases.

nohz_full:

This kernel option sets adaptive tick mode (NOHZ_FULL) to specified processors. Since the number of interrupts is reduced to ones per second, latency-sensitive applications can take advantage of it.

Memory Interleaving:

When Enabled, memory interleaving is supported if a symmetric memory configuration is installed. When set to Disabled, the system supports Non-Uniform Memory Access (NUMA) (asymmetric) memory configurations. Channel interleaving is available with all configurations and is the intra-die memory interleave option. With channel interleaving the memory behind each UMC will be interleaved and seen as 1 NUMA domain per die.


Flag description origin markings:

[user] Indicates that the flag description came from the user flags file.
[suite] Indicates that the flag description came from the suite-wide flags file.
[benchmark] Indicates that the flag description came from a per-benchmark flags file.

The flags files that were used to format this result can be browsed at
http://www.spec.org/cpu2017/flags/gcc.2018-02-16.html,
http://www.spec.org/cpu2017/flags/aocc130-flags-revA2.html,
http://www.spec.org/cpu2017/flags/Dell-Platform-Flags-PowerEdge14G-revE2.html.

You can also download the XML flags sources by saving the following links:
http://www.spec.org/cpu2017/flags/gcc.2018-02-16.xml,
http://www.spec.org/cpu2017/flags/aocc130-flags-revA2.xml,
http://www.spec.org/cpu2017/flags/Dell-Platform-Flags-PowerEdge14G-revE2.xml.


For questions about the meanings of these flags, please contact the tester.
For other inquiries, please contact info@spec.org
Copyright 2017-2019 Standard Performance Evaluation Corporation
Tested with SPEC CPU2017 v1.0.5.
Report generated on 2019-04-16 17:19:48 by SPEC CPU2017 flags formatter v5178.