Intel Compilers

Set-up on Owens

After you ssh to Owens, the default version of Intel compilers will be loaded for you automatically. 

Using the Intel Compilers

Once the intel compiler module has been loaded, the compilers are available for your use. See our compilation guide for suggestions on how to compile your software on our systems. The following table lists common compiler options available in all languages.

COMPILER OPTION	PURPOSE
-c	Compile only; do not link
-DMACRO[=value]	Defines preprocessor macro MACRO with optional value (default value is 1)
-g	Enables debugging; disables optimization
-I/directory/name	Add /directory/name to the list of directories to be searched for #include files
-L/directory/name	Adds /directory/name to the list of directories to be searched for library files
-lname	Adds the library libname.a or libname.so to the list of libraries to be linked
-o outfile	Names the resulting executable outfile instead of a.out
-UMACRO	Removes definition of MACRO from preprocessor
-v	Emit version including gcc compatibility; see below
	Optimization Options
-O0	Disable optimization
-O1	Light optimization
-O2	Heavy optimization (default)
-O3	Aggressive optimization; may change numerical results
-ipo	Inline function expansion for calls to procedures defined in separate files
-funroll-loops	Loop unrolling
-parallel	Automatic parallelization
-openmp	Enables translation of OpenMP directives

The following table lists some options specific to C/C++

-strict-ansi	Enforces strict ANSI C/C++ compliance
-ansi	Enforces loose ANSI C/C++ compliance
-std=val	Conform to a specific language standard

The following table lists some options specific to Fortran

-convert big_endian	Use unformatted I/O compatible with Sun and SGI systems
-convert cray	Use unformatted I/O compatible with Cray systems
-i8	Makes 8-byte INTEGERs the default
-module /dir/name	Adds /dir/name to the list of directories searched for Fortran 90 modules
-r8	Makes 8-byte REALs the default
-fp-model strict	Disables optimizations that can change the results of floating point calculations

Intel compilers use the GNU tools on the clusters:  header files, libraries, and linker.  This is called the Intel and GNU compatibility and interoperability.  Use the Intel compiler option -v to see the gcc version that is currently specified.  Most users will not have to change this.  However, the gcc version can be controlled by users in several ways. 

On OSC clusters the default mechanism of control is based on modules.  The most noticeable aspect of interoperability is that some parts of some C++ standards are available by default in various versions of the Intel compilers; other parts require you to load an extra module.  The C++ standard can be specified with the Intel compiler option -std=val; see the compiler man page for valid values of val.  If you specify a particular standard then load the corresponding module; the most common Intel compiler version and C++ standard combinations, that are applicable to this cluster, are described below:

For the C++14 standard with an Intel 16 compiler:

module load cxx14

With an Intel 17 or 18 compiler, module cxx17 will be automatically loaded by the intel module load command to enable the GNU tools necessary for the C++17 standard.   With an Intel 19 compiler, module gcc-compatibility will be automatically loaded by the intel module load command to enable the GNU tools necessary for the C++17 standard.  (In early 2020 OSC changed the name of these GNU tool controlling modules to clarify their purpose and because our underlying implementation changed.)

A symptom of broken gcc-compatibility is unusual or non sequitur compiler errors typically involving the C++ standard library especially with respect to template instantiation, for example:

    error: more than one instance of overloaded function "std::to_string" matches the argument list:
              detected during:
                instantiation of "..."

    error: class "std::vector<std::pair<short, short>, std::allocator<std::pair <short, short>>>" has no member "..."
              detected during:
                instantiation of "..."

An alternative way to control compatibility and interoperability is with Intel compiler options; see the "GNU gcc Interoperability" sections of the various Intel compiler man pages for details.

Batch Usage on Owens

When you log into owens.osc.edu you are actually logged into a linux box referred to as the login node. To gain access to the mutiple processors in the computing environment, you must submit your job to the batch system for execution. Batch jobs can request mutiple nodes/cores and compute time up to the limits of the OSC systems. Refer to Queues and Reservations and Batch Limit Rules for more info. 

Interactive Batch Session

For an interactive batch session on Owens, one can run the following command:

sinteractive -A <project-account> -N 1 -n 28 -t 1:00:00

which gives you 1 node with 28 cores ( -N 1 -n 28 ) with 1 hour ( -t 1:00:00 ). You may adjust the numbers per your need.

Non-interactive Batch Job (Serial Run)

A batch script can be created and submitted for a serial or parallel run. You can create the batch script using any text editor you like in a working directory on the system of your choice. The following example batch script file will use the input file named  hello.c  and the output file named  hello_results . Below is the example batch script ( job.txt ) for a serial run:

#!/bin/bash
#SBATCH --time=1:00:00 
#SBATCH --nodes=1 --ntasks-per-node=28 
#SBATCH --job-name jobname 
#SBATCH --account=<project-account>

module load intel 
cp hello.c $TMPDIR 
cd $TMPDIR 
icc -O2 hello.c -o hello 
./hello > hello_results 
cp hello_results $SLURM_SUBMIT_DIR

In order to run it via the batch system, submit the  job.txt  file with the following command:

sbatch job.txt

Non-interactive Batch Job (Parallel Run)

Below is the example batch script ( job.txt ) for a parallel run:

#!/bin/bash
#SBATCH --time=1:00:00
#SBATCH--nodes=2 --ntasks-per-node=40
#SBATCH --job-name name
#SBATCH --account=<project-account>

module load intel
mpicc -O2 hello.c -o hello
cp hello $TMPDIR
cd $TMPDIR
mpiexec ./hello > hello_results
cp hello_results $SLURM_SUBMIT_DIR

Set-up on Pitzer

After you ssh to Pitzer, the default version of Intel compilers will be loaded for you automatically. 

Using the Intel Compilers

Once the intel compiler module has been loaded, the compilers are available for your use. See our compilation guide for suggestions on how to compile your software on our systems. The following table lists common compiler options available in all languages.

COMPILER OPTION	PURPOSE
-c	Compile only; do not link
-DMACRO[=value]	Defines preprocessor macro MACRO with optional value (default value is 1)
-g	Enables debugging; disables optimization
-I/directory/name	Add /directory/name to the list of directories to be searched for #include files
-L/directory/name	Adds /directory/name to the list of directories to be searched for library files
-lname	Adds the library libname.a or libname.so to the list of libraries to be linked
-o outfile	Names the resulting executable outfile instead of a.out
-UMACRO	Removes definition of MACRO from preprocessor
-v	Emit version including gcc compatibility; see below
	Optimization Options
-O0	Disable optimization
-O1	Light optimization
-O2	Heavy optimization (default)
-O3	Aggressive optimization; may change numerical results
-ipo	Inline function expansion for calls to procedures defined in separate files
-funroll-loops	Loop unrolling
-parallel	Automatic parallelization
-openmp	Enables translation of OpenMP directives

The following table lists some options specific to C/C++

-strict-ansi	Enforces strict ANSI C/C++ compliance
-ansi	Enforces loose ANSI C/C++ compliance
-std=val	Conform to a specific language standard

The following table lists some options specific to Fortran

-convert big_endian	Use unformatted I/O compatible with Sun and SGI systems
-convert cray	Use unformatted I/O compatible with Cray systems
-i8	Makes 8-byte INTEGERs the default
-module /dir/name	Adds /dir/name to the list of directories searched for Fortran 90 modules
-r8	Makes 8-byte REALs the default
-fp-model strict	Disables optimizations that can change the results of floating point calculations

Intel compilers use the GNU tools on the clusters:  header files, libraries, and linker.  This is called the Intel and GNU compatibility and interoperability.  Use the Intel compiler option -v to see the gcc version that is currently specified.  Most users will not have to change this.  However, the gcc version can be controlled by users in several ways. 

On OSC clusters the default mechanism of control is based on modules.  The most noticeable aspect of interoperability is that some parts of some C++ standards are available by default in various versions of the Intel compilers; other parts require an extra module.  The C++ standard can be specified with the Intel compiler option -std=val; see the compiler man page for valid values of val.

With an Intel 17 or 18 compiler, module cxx17 will be automatically loaded by the intel module load command to enable the GNU tools necessary for the C++17 standard.   With an Intel 19 compiler, module gcc-compatibility will be automatically loaded by the intel module load command to enable the GNU tools necessary for the C++17 standard.  (In early 2020 OSC changed the name of these GNU tool controlling modules to clarify their purpose and because our underlying implementation changed.)

A symptom of broken gcc-compatibility is unusual or non sequitur compiler errors typically involving the C++ standard library especially with respect to template instantiation, for example:

    error: more than one instance of overloaded function "std::to_string" matches the argument list:
              detected during:
                instantiation of "..."

    error: class "std::vector<std::pair<short, short>, std::allocator<std::pair <short, short>>>" has no member "..."
              detected during:
                instantiation of "..."

An alternative way to control compatibility and interoperability is with Intel compiler options; see the "GNU gcc Interoperability" sections of the various Intel compiler man pages for details.

 

C++ Standard	GNU	Intel
C++11	> 4.8.1	> 14.0
C++14	> 6.1	> 17.0
C++17	> 7	> 19.0
C++2a	features available since 8

 

Batch Usage on Pitzer

When you log into owens.osc.edu you are actually logged into a linux box referred to as the login node. To gain access to the mutiple processors in the computing environment, you must submit your job to the batch system for execution. Batch jobs can request mutiple nodes/cores and compute time up to the limits of the OSC systems. Refer to Queues and Reservations and Batch Limit Rules for more info. 

Interactive Batch Session

For an interactive batch session on Pitzer, one can run the following command:

sinteractive -A <project-account> -N 1 -n 40 -t 1:00:00

which gives you 1 node (-N 1), 40 cores ( -n 40), and 1 hour ( -t 1:00:00). You may adjust the numbers per your need.

Non-interactive Batch Job (Serial Run)

A batch script can be created and submitted for a serial or parallel run. You can create the batch script using any text editor you like in a working directory on the system of your choice. The following example batch script file will use the input file named  hello.c  and the output file named  hello_results . Below is the example batch script ( job.txt ) for a serial run:

#!/bin/bash
#SBATCH --time=1:00:00
#SBATCH --nodes=1 --ntasks-per-node=40
#SBATCH --job-name hello
#SBATCH --account=<project-account>

module load intel
cp hello.c $TMPDIR
cd $TMPDIR
icc -O2 hello.c -o hello
./hello > hello_results
cp hello_results $SLURM_SUBMIT_DIR

In order to run it via the batch system, submit the   job.txt  file with the following command:

sbatch job.txt

Non-interactive Batch Job (Parallel Run)

Below is the example batch script ( job.txt ) for a parallel run:

#!/bin/bash
#SBATCH --time=1:00:00
#SBATCH --nodes=2 --ntasks-per-node=40
#SBATCH --job-name name
#SBATCH --account=<project-account>

module load intel
module laod intelmpi
mpicc -O2 hello.c -o hello
cp hello $TMPDIR
cd $TMPDIR
sun ./hello > hello_results
cp hello_results $SLURM_SUBMIT_DIR