Fujitsu Siemens Computers SPEC CPU2006 Flag Description

Compilers: Intel Compilers for C++ and Fortran, Version 9.1 for IA32/EM64T-based applications in Linux_x64
Operating system: 64-bit SUSE Linux 10 Enterprise Edition
Last updated: 27-Mar-2007 PS

The text for many of the descriptions below was taken from the documentation of the Intel Compilers. This documentation is copyright © 2006 Intel Corporation. All Rights Reserved.
The original documentation is distributed with the Intel compilers.

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Platform settings

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

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 an 128-byte sector that contains the data needed due to a cache line miss.

-I

Compiler option to set the path for include files.
Used in some integer peak benchmarks which were built using the Intel 64-bit compiler. Used in some floating point peak benchmarks which were built using the Intel 32-bit compiler.

-L

Compiler option to set the path for library files.
Used in some integer peak benchmarks which were built using the Intel 64-bit compiler. Used in some floating point peak benchmarks which were built using the Intel 32-bit compiler.

ulimit -s

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

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]
$MYMASK: The bitmask (in hexadecimal) corresponding to a specific SPECCOPYNUM. For example, $MYMASK value for the first copy of a rate run will be 0x00000001, for the second copy of the rate will be 0x00000002 etc. Thus, the first copy of the rate run will have a CPU affinity of CPU0, the second copy will have the affinity CPU1 etc.
$command: Program to be started, in this case, the benchmark instance to be started.

]]> -fast Maximize speed across the entire program.

Turns on:

-O3
-no-prec-div
-xP
-ipo
-static

]]> -O3 Optimizes for speed. Enables high-level optimization. This level does not guarantee higher performance. Using this option may increase the compilation time. Impact on performance is application dependent, some applications may not see a performance improvement.

The optimizations include:

All optimizations done with -O2
loop unrolling, including instruction scheduling
code replication to eliminate branches
padding the size of certain power-of-two arrays to allow more efficient cache use.
When used with -ax or -x, it causes the compiler to perform more aggressive data dependency analysis than for -O2.

]]> -no-prec-div Enables[disables] improved precision of floating-point divides. Disabling may slightly improve speed. Default Enabled.

]]> -xP -xprocessor This option directs the compiler to generate specialized and optimized code for the Intel processor that executes your program. It lets you target your program to run on a specific Intel processor.

processor Is the processor for which you want to target your program.
Here: P Code is optimized for Intel Core Duo processors, Intel Core Solo processors, Intel Pentium 4 processors with Steaming SIMD Extensions 3, and compatible Intel processors with Streaming SIMD Extensions 3. The resulting code may contain unconditional use of features that are not supported on other processors.
This option also enables new optimizations in addition to Intel processor-specific optimizations including advanced data layout and code restructuring optimizations to improve memory accesses for Intel processors.

Programs compiled with -xP will display a fatal run-time error if they are executed on unsupported processors.

On Intel EM64T systems, W, and P, are the only valid processor values.

]]> -ipo -ipo[n]

This option enables interprocedural optimizations between files. This is also called multifile interprocedural optimization (multifile IPO) or Whole Program Optimization (WPO).

When you specify this option, the compiler performs inline function expansion for calls to functions defined in separate files.

You cannot specify the names for the object files that are created.

n Is an optional integer that specifies the number of object files the compiler should create. The integer must be greater than or equal to 0.
If you do not specify n, the default is 0.

If n is 0, the compiler decides whether to create one or more object files based on an estimate of the size of the application. It generates one object file for small applications, and two or more object files for large applications.

If n is greater than 0, the compiler generates n object files, unless n exceeds the number of source files (m), in which case the compiler generates only m object files.

]]> -static -static prevents linking with shared libraries.

]]> -O2 Optimizes for speed.
The -O2 option includes the following options:

-Og
-Oi-
-Os
-Oy
-Ob1
-Gs

This options defaults to ON.

This option also enables:

inlining of intrinsics
Intra-file interprocedural optimizations including:

inlining
constant propagation
forward substitution
routine attribute propagation
variable address-taken analysis
dead static function elimination
removal of unreferenced variables.

The following performance optimizations:

copy propogation.
dead-code elimination
global register allocation
global instruction scheduling and control speculation
loop unrolliing
optimized code selection
partial redundancy elimination
strength reduction/induction variable simplification
variable renaming
exception handling optimizations
tail recursions
peephole optimizations
structure assignment lowering and optimization
dead store elimination

]]> -prof_gen This option instruments a program for profiling as first step in Profile Guided Optimization.

Profile Guided Optimization (PGO) consists of 3 phases:
Phase 1: Compile and generate instrumented code in preparation to gather profiling information (compiler flag -prof_gen).
Phase 2: Execute the instrumented code and gather profiling information.
Phase 3: Recompile the code and use the profiling information for improved optimization (compiler flag -prof_use).

The option -prof_gen instruments a program for profiling to get the execution count of each basic block. It also creates a new static profile information file (.spi). This flag is used in phase 1 of the Profile Guided Optimizer (PGO) to instruct the compiler to produce code in your object files in preparation for instrumented execution.

The instrumented code

Gathers information regarding execution paths.
Gathers information regarding data values.
Does not use hardware performance counters.

]]> -prof_use This option enables the use of profiling information during optimization as final step in Profile Guided Optimization.

The option -prof_use instructs the compiler to use the profiling information from phase 2 of PGO in order to produce a profile-optimized executable (phase 3 of PGO).

It also enables function splitting (option -Qfnsplit) and function grouping during optimization.

Note that there is no way to turn off function grouping if you enable it using this option.

The recompilation with -prof_use

Uses information regarding execution paths.
Uses information regarding data values.
Does not use hardware performance counters.
Uses techniques (like function grouping) which are not available without PGO.

]]> -fnsplit Enables function splitting.

This option enables function splitting if -prof-use is also specified. Otherwise, this option has no effect.

It is enabled automatically if you specify -prof-use. If you do not specify one of those options, the default is -fnsplit-, which disables function splitting but leaves function grouping enabled.

To disable function splitting when you use -prof-use, specify -fnsplit-.

]]> -Og Enables global optimizations.

]]> -Oi Enables/disables inline expansion of intrinsic functions.

Default enabled

]]> -Os This option enables most speed optimizations, but disables some that increase code size for a small speed benefit.

Default enabled

]]> -Oy Enables [disables] the use of the EBP register in optimizations. When you disable with -Oy-, the EBP register is used as frame pointer. -Oy has the effect of reducing the number of general-purpose registers by 1, and can produce slightly less efficient code.

Default enabled

]]> -Ob<n> n = 0
Disables inlining of user-defined functions. However, statement functions are always inlined

n = 1
Enables inlining of functions declared with the __inline keyword. Also enables inlining according to the C++ language

n = 2
Enables inlining of any function. However, the compiler decides which functions are inlined. This option enables interprocedural optimizations and has the same effect as specifying option ip.

Default enabled with n = 2

]]> -Gs Disables stack-checking for routines with n or more bytes of local variables and compiler temporaries.

Default enabled with n = 4096.

]]> -Oa Assume [not assume] no aliasing

Default disabled

]]> -Ot Enables all speed optimizations.

Overrides -Os

]]> -Ow Assume[not assume] no cross function aliasing.

]]> -Gf Enables string-pooling optimization.

]]> -Gy Packages functions to enable linker optimization.

Default enabled

]]> -axP Generates specialized code for processor specific codes W, P while also generating generic IA-32 code.

W = Intel Pentium 4 and compatible Intel processors
P = Intel Pentium 4 processor with Streaming SIMD 3 (SSE3) support. These option also enable advanced data layout and code restructuring optimizations to improve memory accesses for Intel processors.

]]> -L/opt/SmartHeap_8_1/lib -lsmartheap Link with SmartHeap Library.
Available from: http://www.microquill.com

]]> -DSPEC_CPU_LP64 -DSPEC_CPU_LP64 compiles using LP64 programming model.

]]> -DSPEC_CPU_LINUX_X64 Compile for an I386 system running Linux.

]]> -DSPEC_CPU_LINUX -DSPEC_CPU_LINUX compiles for a system running Linux.

]]> -nofor_main For mixed-language benchmarks, tell the compiler that the main program is not written in Fortran.

]]> -DSPEC_CPU_CASE_FLAG This macro indicates that Fortran functions called from C should have their names lower-cased.

]]> /opt/intel/fc/9.1.043/bin/ifort /opt/intel/fc/9.1.043/bin/ifort invokes the 32-bit Intel Fortran compiler.
Also used to invoke linker for 32-bit programs in Fortran and C/Fortran mixtures.

]]> ifort Invoke the 64-bit Intel Fortran compiler.
Also used to invoke linker for 64-bit programs in Fortran and C/Fortran mixtures.

]]> /opt/intel/cc/9.1.047/bin/icc /opt/intel/cc/9.1.047/bin/icc invokes the 32-bit Intel C compiler.
Also used to invoke linker for 32-bit C programs.

]]> /opt/intel/cce/9.1.047/bin/icc /opt/intel/cce/9.1.047/bin/icc invokes the 64-bit Intel C compiler.
Also used to invoke linker for 64-bit C programs.

]]> /opt/intel/cc/9.1.047/bin/icpc /opt/intel/cc/9.1.047/bin/icpc invokes the 32-bit Intel C++ compiler.
Also used to invoke linker for 32-bit C++ programs.

]]> icc Invoke the Intel C compiler.
Also used to invoke linker for C programs.

]]> icpc Invoke the Intel C++ compiler.
Also used to invoke linker for C++ programs.

]]> -I/opt/intel/cc/9.1.047/include -I/opt/intel/cc/9.1.047/include is the include path of 32-bit Intel C/C++ compiler

]]> -I/opt/intel/cce/9.1.047/include -I/opt/intel/cce/9.1.047/include is the include path of 64-bit Intel C/C++ compiler

]]> -L/opt/intel/cc/9.1.047/lib -L/opt/intel/cc/9.1.047/lib is the library path of 32-bit Intel C/C++ compiler

]]> -L/opt/intel/cce/9.1.047/lib -L/opt/intel/cce/9.1.047/lib is the library path of 64-bit Intel C/C++ compiler

]]> -I/opt/intel/fc/9.1.043/include -I/opt/intel/fc/9.1.043/include is the include path of 32-bit Intel Fortran compiler

]]> -L/opt/intel/fc/9.1.043/lib -L/opt/intel/fc/9.1.043/lib is the library path of 32-bit Intel Fortran compiler

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