CPU2017 Flag Description
Cisco Systems Cisco UCS C125 (AMD EPYC 7501)

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 aocc100-flags-revC-I

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

Compilers: AOCC Suite


Base Compiler Invocation

C benchmarks

C++ benchmarks

Fortran benchmarks


Base Portability Flags

500.perlbench_r

502.gcc_r

505.mcf_r

520.omnetpp_r

523.xalancbmk_r

525.x264_r

531.deepsjeng_r

541.leela_r

548.exchange2_r

557.xz_r


Base Optimization Flags

C benchmarks

C++ benchmarks

Fortran benchmarks


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 aocc100-flags-revC-I

AMD Optimizing C/C++ Compiler Suite 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 effect 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 memory on the local node while "-m" specifies which node(s) to place a process memory. For full details on using numactl, please refer to your Linux documentation, 'man numactl'

Note that some versions of numactl, particularly the version found on SLES 10, we have found that the utility incorrectly interprets application arguments as it's own. For example, with the command "numactl --physcpubind=0 -l a.out -m a", numactl will interpret a.out's "-m" option as it's own "-m" option. To work around this problem, a user can 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 aocc100-flags-revC-I

AMD Optimizing C/C++ Compiler Suite 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 and manually set the Huge Pages you can follow the below steps:

Note that further information about huge pages may be found in your Linux documentation file: /usr/src/linux/Documentation/vm/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.

OMP_NUM_THREADS

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

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.

LD_LIBRARY_PATH

An environment variable set to include the LLVM, JEMalloc and SmartHeap libraries used during compilation of the binaries. This environment variable setting is not needed when building the binaries on the system under test.

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.
*** 0 - Turn the process address space randomization off. This is the default for architectures that do not support this feature anyways, and kernels that are booted with the "norandmaps" parameter.
*** 1 - Make the addresses of mmap base, stack and VDSO page randomized. This, among other things, implies that shared libraries will be loaded to random addresses. Also for PIE-linked binaries, the location of code start is randomized. This is the default if the CONFIG_COMPAT_BRK option is enabled.
*** 2 - Additionally enable heap randomization. This is the default if CONFIG_COMPAT_BRK is disabled.

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.


Operating System Tuning Parameters

Operating System and Software Tuning Parameters

ulimit -s <n>

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

numactl --interleave=all "runspec command"

Launching a process with numactl --interleave=all sets the memory interleave policy so that memory will be allocated using round robin on nodes. When memory cannot be allocated on the current interleave target fall back to other nodes.

Free the file system page cache

The command "echo 1> /proc/sys/vm/drop_caches" is used to free up the filesystem page cache.

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 memory on the local node while "-m" specifies which node(s) to place a process memory. For full details on using numactl, please refer to your Linux documentation, 'man numactl'

dirty_background_ratio

This is the percentage of the total amount of free and reclaimable memory. When the amount of dirty pagecache exceeds this percentage, writeback threads start writing back dirty memory. This setting can help Linux disk caching and performance by setting the percentage of system memory that can be filled with dirty pages. This can be set through a command like "echo 40 > /proc/sys/vm/dirty_background_ratio".

swappiness

This control is used to define how aggressively the kernel swaps out anonymous memory relative to pagecache and other caches. Increasing the value increases the amount of swapping. The default value is 60. 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".

Zone Reclaim Mode

This parameter controls whether memory reclaim is performed on a local NUMA node even if there is plenty of memory free on other nodes. This parameter is automatically turned on on machines with more pronounced NUMA characteristics. 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".

dirty_ratio

A percentage value. When this percentage of total system memory is modified, the system begins writing the modifications to disk with the pdflush operation. The default value is 20 percent. 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". This can be set through a command "echo 8 > /proc/sys/vm/dirty_ratio".

Linux Huge Page settings

In order to take advantage of large pages, your system must be configured to use large pages. To configure your system for huge pages perform the following steps:

Create a mount point for the huge pages: "mkdir /mnt/hugepages" The huge page file system needs to be mounted when the systems reboots. Add the following to a system boot configuration file before any services are started: "mount -t hugetlbfs nodev /mnt/hugepages" Set vm/nr_hugepages=N in your /etc/sysctl.conf file where N is the maximum number of pages the system may allocate. Reboot to have the changes take effect. (Not necessary on some operating systems like RedHat Enterprise Linux 5.5).

Note that further information about huge pages may be found in your Linux documentation file: /usr/src/linux/Documentation/vm/hugetlbpage.txt

Transparent Huge Pages

On RedHat EL 6 and later, Transparent Hugepages increases the memory page size from 4 kilobytes to 2 megabytes. Transparent Hugepages 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. Hugepages are used by default if /sys/kernel/mm/redhat_transparent_hugepage/enabled is set to always.

HUGETLB_MORECORE

Set this environment variable to "yes" to enable applications to use large pages.

KMP_STACKSIZE

Specify stack size to be allocated for each thread.

KMP_AFFINITY

KMP_AFFINITY = < physical | logical >, starting-core-id specifies the static mapping of user threads to physical cores. For example, if you have a system configured with 8 cores, OMP_NUM_THREADS=8 and KMP_AFFINITY=physical,0 then thread 0 will mapped to core 0, thread 1 will be mapped to core 1, and so on in a round-robin fashion. KMP_AFFINITY = granularity=fine,scatter The value for the environment variable KMP_AFFINITY affects how the threads from an auto-parallelized program are scheduled across processors. Specifying granularity=fine selects the finest granularity level, causes each OpenMP thread to be bound to a single thread context. This ensures that there is only one thread per core on cores supporting HyperThreading Technology Specifying scatter distributes the threads as evenly as possible across the entire system. Hence a combination of these two options, will spread the threads evenly across sockets, with one thread per physical core.

OMP_NUM_THREADS

Sets the maximum number of threads to use for OpenMP* parallel regions if no other value is specified in the application. This environment variable applies to both -openmp and -parallel (Linux and Mac OS X) or /Qopenmp and /Qparallel (Windows). Example syntax on a Linux system with 8 cores: export OMP_NUM_THREADS=8


Firmware / BIOS / Microcode Settings

Determinism Slider

This option allows the processor to use a given performance level as the max cap, or to let the processor operate as close to the thermal design point (TDP) as possible. Values for this BIOS option can be: Power: Processor operates as close to the TDP as possible. Performance: Processor operates at a capped performance level as the max operating state.

High Bandwidth:

Enabling this option allows the chipset to defer memory transactions and process them out of order for optimal performance.

submit= MYMASK=`printf '0x%x' \$((1<< \$SPECCOPYNUM))`; /usr/bin/taskset \$MYMASK $command

When running multiple copies of benchmarks, the SPEC config file feature submit is sometimes used to cause individual jobs to be bound to specific processors. This specific submit command is used for Linux. The description of the elements of the command are:

/usr/bin/taskset [options] [mask] [pid | command [arg] ... ] :
taskset is used to set or retreive the CPU affinity of a running process given its PID or to launch a new COMMAND with a given CPU affinity. The CPU affinity is represented as a bitmask, with the lowest order bit corresponding to the first logical CPU and highest order bit corresponding to the last logical CPU. When the taskset returns, it is guaranteed that the given program has been scheduled to a legal CPU.
:
The default behaviour of taskset is to run a new command with a given affinity mask: :
taskset [mask] [command] [arguments]

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/aocc100-flags-revC-I.2018-02-16.html,
http://www.spec.org/cpu2017/flags/Cisco-Platform-Settings-AMD-V1-revA.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/aocc100-flags-revC-I.2018-02-16.xml,
http://www.spec.org/cpu2017/flags/Cisco-Platform-Settings-AMD-V1-revA.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 v1.0.2.
Report generated on 2019-02-21 17:32:21 by SPEC CPU2017 flags formatter v5178.