Setting Environment Variables

CILK_NWORKERS (Linux* OS)

Specifies the number of worker threads to use in an Intel® Cilk™ Plus program.

See Set Worker Count.

GCCROOT

Specifies the location of the gcc binaries. Set this variable only when the compiler cannot locate the gcc binaries when using the -gcc-name option.

GXX_INCLUDE

Specifies the location of the gcc headers. Set this variable to specify the locations of the GCC installed files when the compiler does not find the needed values as specified by the use of the -gcc-name=<directory-name>/gcc option.

GXX_ROOT

Specifies the location of the gcc binaries. Set this variable to specify the locations of the GCC installed files when the compiler does not find the needed values as specified by the use of the -gcc-name=<directory-name>/gcc option.

IA32ROOT (IA-32 architecture and Intel® 64 architecture)

Points to the directories containing the include and library files for a non-standard installation structure.

ICCCFG

Specifies the configuration file for customizing compilations when invoking the compiler using icc.

ICPCCFG

Specifies the configuration file for customizing compilations when invoking the compiler using icpc.

INTEL_CHKP_REPORT_MODE (Linux* OS)

Changes the pointer checker reporting mode at runtime.

See Finding and Reporting Out-of-Bounds Errors.

INTEL_LICENSE_FILE

Specifies the location for the Intel license file.

LD_LIBRARY_PATH (Linux* OS)

Specifies the location for shared objects.

PATH

Specifies the directories the system searches for binary executable files.

PROF_DIR

PROF_DPI

TMP

TMPDIR

TEMP

Specifies the location for temporary files. If none of these are specified, the compiler stores temporary files in /tmp.

MIC_ENV_PREFIX

Used to control environment variables passed to the coprocessor.

By default, all environment variables set on the host are passed to the coprocessor. Setting MIC_ENV_PREFIX passes only environment variables that have a prefix of the value of this variable. For example, setting setenv MIC_ENV_PREFIX=MIC passes only environment variables that have a prefix of MIC.

For information on passing environment variables to a particular coprocessor, and on passing multiple environment variables to one or all coprocessors, see Setting Environment Variables on the CPU to Modify the Coprocessor's Execution Environment.

MIC_HOST_LOG

A string containing the file name to output traces from the host.

Default: None

Example: MIC_HOST_LOG=/home/user/app/host.log

MIC_LD_LIBRARY_PATH

Specifies the location for target shared objects. LD_LIBRARY_PATH specifies the location for host objects.

MIC_PROXY_IO

Enables (1) or disables (0) the proxy of stderr and stdout, and specifies whether the process wants I/O proxy support between the host and coprocessor.

Default: 1

Example: MIC_PROXY_IO=0

MIC_SEP_MONITOR

Enables (1) or disables (0) SEP at offload regions.

Default: 0

Example: MIC_SEP_MONITOR=1

MIC_STACKSIZE

Specifies the stack size of the main thread for the offload. This value is typically much larger than the stack size for individual threads. It corresponds to what you would set with ulimit -s (BASH shell) or limit stacksize (C shell) if you were running natively on either the coprocessor or the host.

Set this variable to integerB|K|M|G|T, where:

• B = bytes

• K = kilobytes

• M = megabytes

• G = gigabytes

• T = terabytes

Default: 12M

Example: MIC_STACKSIZE=16M

MIC_USE_2MB_BUFFERS

Use 2M pages for (size > MIC_USE_2MB_BUFFERS). Pointer-based variables whose runtime length exceeds the value of this variable will be allocated in large pages.

Set this variable to integerB|K|M|G|T, where:

• B = bytes

• K = kilobytes

• M = megabytes

• G = gigabytes

• T = terabytes

Example: MIC_USE_2MB_BUFFERS=64K

OFFLOAD_DEVICES

Restricts the offload process to use only the coprocessors specified as the value of the variable.

Set this variable to a comma separated list of coprocessor device numbers in the range 0 to number_of_devices_in_the_system-1, where 0 is the first coprocessor in the system, and number_of_devices_in_the_system-1 is the last coprocessor in the system.

Coprocessors available for offloading are numbered logically. The function _Offload_number_of_devices() returns the number of available coprocessors. Coprocessor indices that you use in the target specifier of the offload pragmas are in the range 0 to number_of_devices_in_the_system-1.

Default: The offload process uses all devices.

Example: OFFLOAD_DEVICES = 1,2

On a system with more than two coprocessors installed, this setting enables the application to use only coprocessors 1 and 2. Offloads to coprocessors 0 or 1 are performed on the first and second physical coprocessors. Offloads to target numbers higher than 1 wrap-around so that all offloads remain within coprocessors 0 and 1. The function _Offload_number_of_devices() executed on a coprocessor return 0 or 1, when the offload is running on the first or second coprocessor.

OFFLOAD_INIT

Specifies a hint to the offload runtime when to initialize coprocessors.

Supported values:

• on_start: All available coprocessors are initialized before entering main.

• on_offload: The coprocessor is initialized immediately before the first offload to it. Initialization is done only on the coprocessor that handles the offload.

• on_offload_all: All available coprocessors are initialized immediately before the first offload in an application.

Default: on_offload_all

Example: OFFLOAD_INIT=on_start

OFFLOAD_REPORT

Controls printing offload execution time, in seconds, and the amount of data transferred, in bytes. This environment variable is equivalent to using the __Offload_report API.

Supported values:

• 1: Produces a report about time taken.

• 2: In additon to the information produced at value 1, adds the amount of data transferred between the CPU and the coprocessor.

• 3: In addition to the information produced at value 2, gives additional details on offload activity, including device initialization, and individual variable transfers.

Default: None

Example: OFFLOAD_REPORT=1

See also __Offload_report.

KMP_AFFINITY

Enables run-time library to bind threads to physical processing units.

Default: none

KMP_ALL_THREADS

Limits the number of simultaneously executing threads in an OpenMP* program. If this limit is reached and another native operating system thread encounters OpenMP* API calls or constructs, then the program may abort with an error message. If this limit is reached at the time an OpenMP parallel region begins, a one-time warning message may be generated indicating that the number of threads in the team was reduced, but the program will continue execution.

This environment variable is only used for programs compiled with openmp option .

Default: No enforced limit

KMP_BLOCKTIME

Sets the time, in milliseconds, that a thread should wait, after completing the execution of a parallel region, before sleeping.

Use the optional character suffixes: s (seconds), m (minutes), h (hours), or d (days) to specify the units.

Default: 200 milliseconds

KMP_CPUINFO_FILE

Specifies an alternate file name for file containing machine topology description. The file must be in the same format as /proc/cpuinfo.

Default: None

KMP_DETERMINISTIC_REDUCTIONS

Enables (1) or disables (0) the use of a specific ordering of the reduction operations for implementing the reduction clause for an OpenMP* parallel region. This has the effect that, for a given number of threads, in a given parallel region, for a given data set and reduction operation, a floating point reduction done for an OpenMP reduction clause will have a consistent floating point result from run to run, since round-off errors will be identical.

Default: 0

KMP_DYNAMIC_MODE

Selects the method used to determine the number of threads to use for a parallel region when OMP_DYNAMIC=true.

Possible values: (asat | load_balance | thread_limit ), where,

• asat: estimates number of threads based on parallel start time;

• load_balance: tries to avoid using more threads than available execution units on the machine;

• thread_limit: tries to avoid using more threads than total execution units on the machine.

Default (IA-32 architecture): load_balance (on all supported OSes)

Default (Intel® MIC architecture):thread_limit (on supported OSes)

KMP_INHERIT_FP_CONTROL

Enables (1) or disables (0) the copying of the floating point control settings of the master thread to the floating point control settings of the OpenMP* worker threads at the start of each parallel region.

Default: 1

KMP_LIBRARY

Selects the OpenMP run-time library execution mode. The values for this variable are serial, turnaround, or throughput .

Default: throughput

KMP_MONITOR_STACKSIZE

Sets the number of bytes to allocate for the monitor thread, which is used for book-keeping during program execution.

Use the optional suffixes: b (bytes), k (kilobytes), m (megabytes), g (gigabytes), or t (terabytes) to specify the units.

Default: max (32k, system minimum thread stack size)

KMP_SETTINGS

Enables (1) or disables (0) the printing of OpenMP run-time library environment variables during program execution. Two lists of variables are printed: user-defined environment variables settings and effective values of variables used by OpenMP run-time library.

Default: 0

KMP_STACKSIZE

Sets the number of bytes to allocate for each OpenMP* thread to use as its private stack. Recommended size is 16m. Use the optional suffix b (bytes), k (kilobytes), m (megabytes), g (gigabytes), or t (terabytes) to specify the allocation. This variable does not affect the native operating system threads created by the user program nor the thread executing the sequential part of an OpenMP* program or parallel programs created using [Q]parallel .

Default (IA-32 architecture): 2m

Default Intel® 64 architecture): 4m.

KMP_VERSION

Enables (1) or disables (0) the printing of OpenMP run-time library version information during program execution.

Default: disabled.

OMP_DYNAMIC

Enables (1) or disables (0) the dynamic adjustment of the number of threads.

Default: 0

Example syntax: export OMP_DYNAMIC=value

OMP_MAX_ACTIVE_LEVELS

Limits the number of simultaneously executing threads in an OpenMP program.

If this limit is reached and another native operating system thread encounters OpenMP API calls or constructs, the program can abort with an error message. If this limit is reached when an OpenMP parallel region begins, a one-time warning message might be generated indicating that the number of threads in the team was reduced, but the program will continue.

This environment variable is only used for programs compiled with the following options: [Q]parallel and [Q]openmp.

omp_get_thread_limit() routine returns the value of the limit.

Default: No enforced limit

Related environment variable: KMP_ALL_THREADS. OMP_THREAD_LIMIT overrides KMP_ALL_THREADS.

Example syntax: export OMP_MAX_ACTIVE_LEVELS=value

OMP_PLACES

An explicit ordered list of places specified as either an abstract name describing a set of places or an explicit list of places described by nonnegative numbers. An exclusion operator “!” can also be used to exclude the number or place immediately following the operator.

For explicit lists, the meaning of the numbers and how the numbering is done for a list of nonnegative numbers are implementation defined. Generally, the numbers represent the smallest unit of execution exposed by the execution environment, typically a hardware thread.

Intervals can be specified using the <lower-bound> : <length> : <stride> notation to represent the following list of numbers:

“<lower-bound>, 
<lower-bound> + <stride>, 
..., 
<lower-bound> +(<length>-1)*<stride>.”

# EXPLICIT LIST EXAMPLE
setenv OMP_PLACES "{0,1,2,3},{4,5,6,7},{8,9,10,11},{12,13,14,15}"
setenv OMP_PLACES "{0:4},{4:4},{8:4},{12:4}"
setenv OMP_PLACES "{0:4}:4:4"

The abstract names listed below should be understood by the execution and runtime environment:

• threads: Each place corresponds to a single hardware thread on the target machine.
• cores: Each place corresponds to a single core (having one or more hardware threads) on the target machine.
• sockets: Each place corresponds to a single socket (consisting of one or more cores) on the target machine.

When requesting fewer places or more resources than available on the system, the determination of which resources of type abstract_name are to be included in the place list is implementation defined. The precise definitions of the abstract names are implementation defined. An implementation may also add abstract names as appropriate for the target platform. The abstract name may be appended by a positive number in parentheses to denote the length of the place list to be created, that is: abstract_name(num-places).

# ABSTRACT NAMES EXAMPLE
setenv OMP_PLACES threads
setenv OMP_PLACES threads(4)

OMP_NESTED

Enables (1) or disables (0)nested parallelism.

Default: 0

Example syntax: export OMP_NESTED=value

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 [Q]parallel and [Q]openmp.

Default: Number of processors visible to the operating system.

Example syntax: export OMP_NUM_THREADS=value

OMP_PROC_BIND

Enables (true) or disables (false) the binding of threads to processor contexts. If enabled, this is the same as specifying KMP_AFFINITY=scatter. If disabled, this is the same as specifying KMP_AFFINITY=none.

If both OMP_PROC_BIND and KMP_AFFINITY are specified, KMP_AFFINITY settings take precedence. GOMP_CPU_AFFINITY also takes precedence over OMP_PROC_BIND.

Default: false

OMP_SCHEDULE

Sets the run-time schedule type and an optional chunk size.

Default: STATIC, no chunk size specified

Example syntax: export OMP_SCHEDULE="kind[,chunk_size]"

OMP_STACKSIZE

Sets the number of bytes to allocate for each OpenMP thread to use as the private stack for the thread. Recommended size is 16M.

Use the optional suffixes: B (bytes), K (Kilobytes), M (Megabytes), G (Gigabytes), or T (Terabytes) to specify the units. If value is specified without suffix, the size is assumed to be K (Kilobytes).

This variable does not affect the native operating system threads created by the user program nor the thread executing the sequential part of an OpenMP program or parallel programs created using [Q]parallel.

kmp_{set,get}_stacksize_s() routines set/retrieve the value. kmp_set_stacksize_s() routine must be called from sequential part, before first parallel region is created. Otherwise, calling kmp_set_stacksize_s() has no effect.

Default (IA-32 architecture): 2M

Default (Intel® 64 architecture): 4M

Related environment variables: KMP_STACKSIZE (overrides OMP_STACKSIZE).

Example syntax: export OMP_STACKSIZE=value

OMP_THREAD_LIMIT

Limits the number of simultaneously executing threads in an OpenMP* program.

If this limit is reached and another native operating system thread encounters OpenMP* API calls or constructs, the program can abort with an error message. If this limit is reached when an OpenMP parallel region begins, a one-time warning message might be generated indicating that the number of threads in the team was reduced, but the program will continue.

This environment variable is only used for programs compiled with the following options: [Q]parallel and [Q]openmp.

omp_get_thread_limit() routine returns the value of the limit.

Default: No enforced limit

Related environment variable: KMP_ALL_THREADS (overrides OMP_THREAD_LIMIT).

Example syntax: export OMP_THREAD_LIMIT=value

OMP_WAIT_POLICY

Decides whether threads spin (active) or sleep (passive) while they are waiting.

Default: Passive

Example syntax: export OMP_WAIT_POLICY=value

GNU* Environment Variables and Extensions

CPATH

Specifies path to include directory for C/C++ compilations.

C_INCLUDE_PATH

Specifies path to include directory for C compilations.

CPLUS_INCLUDE_PATH

Specifies path to include directory for C++ compilations.

DEPENDENCIES_OUTPUT

Specifies how to output dependencies for make based on the non-system header files processed by the compiler. System header files are ignored in the dependency output.

GCC_EXEC_PREFIX

Specifies alternative names for the linker (ld) and assembler (as).

GOMP_CPU_AFFINITY

Specifies a list of OS processor IDs.

Default: Affinity is disabled

GOMP_STACKSIZE

This environment variable is a GNU extension recognized by the Intel® OpenMP* compatibility library.

OMP_STACKSIZE overrides GOMP_STACKSIZE. KMP_STACKSIZE overrides OMP_STACKSIZE and GOMP_STACKSIZE.

LIBRARY_PATH

Specifies a colon-separated list of directories, much like PATH.

SUNPRO_DEPENDENCIES

This variable is the same as DEPENDENCIES_OUTPUT, except that system header files are not ignored.

INTEL_PROF_DUMP_CUMULATIVE

When using interval profile dumping (initiated by INTEL_PROF_DUMP_INTERVAL or the function _PGOPTI_Set_Interval_Prof_Dump) during the execution of an instrumented user application, allows creation of a single .dyn file to contain profiling information instead of multiple .dyn files. If not set, executing an instrumented user application creates a new .dyn file for each interval. Setting this environment variable is useful for applications that do not terminate or those that terminate abnormally (bypass the normal exit code).

INTEL_PROF_DUMP_INTERVAL

Initiates interval profile dumping in an instrumented user application. This environment variable may be used to initiate Interval Profile Dumping in an instrumented application.

PROF_DIR

Specifies the directory in which dynamic information files are created. This variable applies to all three phases of the profiling process.

PROF_DUMP_INTERVAL

Deprecated; use INTEL_PROF_DUMP_INTERVAL instead.

PROF_NO_CLOBBER

Alters the feedback compilation phase slightly. By default, during the feedback compilation phase, the compiler merges data from all dynamic information files and creates a new pgopti.dpi file if the .dyn files are newer than an existing pgopti.dpi file.

When this variable is set the compiler does not overwrite the existing pgopti.dpi file. Instead, the compiler issues a warning. You must remove the pgopti.dpi file if you want to use additional dynamic information files.