CPU2006 Flag Description
Cisco Systems Cisco UCS C260 M2 (Intel Xeon E7-2870, 2.40 GHz)

Copyright © 2006 Intel Corporation. All Rights Reserved. Last updated: April 10th 2012.


Base Compiler Invocation

C benchmarks

C++ benchmarks


Peak Compiler Invocation

C benchmarks (except as noted below)

400.perlbench

401.bzip2

456.hmmer

458.sjeng

C++ benchmarks


Base Portability Flags

400.perlbench

462.libquantum

483.xalancbmk


Peak Portability Flags

400.perlbench

401.bzip2

456.hmmer

458.sjeng

462.libquantum

483.xalancbmk


Base Optimization Flags

C benchmarks

C++ benchmarks


Peak Optimization Flags

C benchmarks

400.perlbench

401.bzip2

403.gcc

429.mcf

445.gobmk

456.hmmer

458.sjeng

462.libquantum

464.h264ref

C++ benchmarks

471.omnetpp

473.astar

483.xalancbmk


Base Other Flags

C benchmarks

403.gcc


Peak Other Flags

C benchmarks

403.gcc


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

submit= MYMASK=`printf '0x%x' $((1<<$SPECCOPYNUM))`; /usr/bin/taskset $MYMASK $command
When running multiple copies of benchmarks, the SPEC config file feature submit is used to cause individual jobs to be bound to specific processors. This specific submit command, using taskset, is used for Linux64 systems without numactl.
Here is a brief guide to understanding the specific command which will be found in the config file:
submit= numactl --localalloc --physcpubind=$SPECCOPYNUM $command
When running multiple copies of benchmarks, the SPEC config file feature submit is used to cause individual jobs to be bound to specific processors. This specific submit command is used for Linux64 systems with support for numactl.
Here is a brief guide to understanding the specific command which will be found in the config file:

Shell, Environment, and Other Software Settings

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.
KMP_STACKSIZE
Specify stack size to be allocated for each thread.
KMP_AFFINITY=[<modifier>,...]<type>[,<permute>][,<offset>]
The value for the environment variable KMP_AFFINITY affects how the threads from an auto-parallelized program are scheduled across processors.
The "<modifier>" argument can be used to set the granularity level of thread scheduling.
The "<type>" argument is used to indicate the thread affinity to use.
The permute and offset argument can be set to 0 or 1.

If you set the number of threads to be equal to the number of cores, specifying KMP_AFFINITY=granularity=fine,scatter 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
Set stack size to unlimited
The command "ulimit -s unlimited" is used to set the stack size limit to unlimited.
Free the file system page cache
The command "echo 1> /proc/sys/vm/drop_caches" is used to free up the filesystem page cache.

Red Hat Specific features

Transparent Huge Pages
On RedHat EL 6 and later, 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.
Hugepages are used by default unless the /sys/kernel/mm/redhat_transparent_hugepage/enabled field is changed from its RedHat EL6 default of 'always'.

Firmware / BIOS / Microcode Settings

Hardware Prefetch:

This BIOS option allows the enabling/disabling of a processor mechanism to prefetch data into the cache according to a pattern-recognition algorithm In some cases, setting this option to Disabled may improve performance. Users should only disable this option after performing application benchmarking to verify improved performance in their environment.

Adjacent Sector Prefetch:

This BIOS option allows the enabling/disabling of a processor mechanism to fetch the adjacent cache line within a 128-byte sector that contains the data needed due to a cache line miss. In some cases, setting this option to Disabled may improve performance. Users should only disable this option after performing application benchmarking to verify improved performance in their environment.

Intel Turbo boost Technology:

Enabling this option allows the processor cores to automatically increase its frequency and increasing performance if it is running below power, temperature.

Intel Hyper Threading Technology:

Enabling this option allows to use processor resources more efficiently, enabling multiple threads to run on each core and increases processor throughput, improving overall performance on threaded software.

Data Reuse Optimization:

Enabling this option allows very active cache lines to stay in the L2 by sending a hint to the L3 to prevent them from aging even if they are not heavily used in the L3. Depending on the specific bios version being used, this option may be called "LRU Hint".

High Bandwidth:

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

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 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'

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 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. 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.

LD_PRELOAD=/usr/lib64/libhugetlbfs.so

Setting this environment variable is necessary 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

submit= $[top]/mysubmit.pl $SPECCOPYNUM "$command"

On Xeon 74xx series processors, some benchmarks at peak will run n/2 copies on a system with n logical processors. The mysubmit.pl script assigns each copy in such a way that no two copies will share an L2 cache, for optimal performance. The script looks in /proc/cpuinfo to come up with the list of cores that will satisfy this requirement.

The source code is shown below.

Source
******************************************************************************************************
#!/usr/bin/perl use strict; use Cwd; # The order in which we want copies to be bound to cores # Copies: 0, 1, 2, 3 # Cores: 0, 1, 3, 6 my $rundir = getcwd; my $copynum = shift @ARGV; my $i; my $j; my $tag; my $num; my $core; my $numofcores; my @proc; my @cores; open(INPUT, "/proc/cpuinfo") or die "can't open /proc/cpuinfo\n"; #open(OUTPUT, "STDOUT"); # proc[i][0] = logical processor ID # proc[i][1] = physical processor ID # proc[i][2] = core ID $i = 0; $numofcores = 0; while(<INPUT>) { chop; ($tag, $num) = split(/\s+:\s+/, $_); if ($tag eq "processor") { $proc[$i][0] = $num; } if ($tag eq "physical id") { $proc[$i][1] = $num; } if ($tag eq "core id") { $proc[$i][2] = $num; $i++; $numofcores++; } } $i = 0; $j = 0; for $core (0, 4, 2, 1, 5, 3) { while ($i < $numofcores) { if ($proc[$i][2] == $core) { $cores[$j] = $proc[$i][0]; $j++; } $i++; } $i=0; } open RUNCOMMAND, "> runcommand" or die "failed to create run file"; print RUNCOMMAND "cd $rundir\n"; print RUNCOMMAND "@ARGV\n"; close RUNCOMMAND; system 'taskset', '-c', $cores[$copynum], 'sh', "$rundir/runcommand";

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/cpu2006/flags/Intel-ic12.1-official-linux64.20120425.html,
http://www.spec.org/cpu2006/flags/Cisco-Platform-Settings-V1.2.html.

You can also download the XML flags sources by saving the following links:
http://www.spec.org/cpu2006/flags/Intel-ic12.1-official-linux64.20120425.xml,
http://www.spec.org/cpu2006/flags/Cisco-Platform-Settings-V1.2.xml.


For questions about the meanings of these flags, please contact the tester.
For other inquiries, please contact webmaster@spec.org
Copyright 2006-2014 Standard Performance Evaluation Corporation
Tested with SPEC CPU2006 v1.2.
Report generated on Thu Jul 24 13:59:42 2014 by SPEC CPU2006 flags formatter v6906.