Sets the schedule type and (optionally) the chunk size for DO and PARALLEL DO loops declared with a schedule of RUNTIME. For these loops, the schedule is set at run time when the system reads the value of this environment variable. Valid values for this environment variable are STATIC, DYNAMIC, and GUIDED. The default value for this environment variable is STATIC.

For DO and PARALLEL DO directives that have a schedule type other than RUNTIME, this environment variable is ignored.

If the optional chunk size is not set, a chunk size of 1 is assumed, except in the case of a STATIC schedule. For a STATIC schedule, the default chunk size is set to the loop iteration space divided by the number of threads applied to the loop.

Sets the number of threads to use during execution, unless that number is explicitly changed by calling the OMP_SET_NUM_THREADS(3) subroutine.

When dynamic adjustment of the number of threads is enabled, the value of this environment variable is the maximum number of threads to use. The default value is the minimum of 8 and the number of CPUs on the system.

Enables or disables dynamic adjustment of the number of threads available for execution of parallel regions.

If set to TRUE, the number of threads that are used for executing parallel regions can be adjusted by the runtime environment to best utilize system resources. The default value is TRUE. If set to FALSE, dynamic adjustment is disabled.

Enables or disables nested parallelism. If set to TRUE, nested parallelism is enabled. If set to FALSE, it is disabled (default).

Controls the barrier implementation within the MP run-time system. This environment variable accepts one of the following values:

Specifies aspects of automatic page migration. Values can be OFF (disables migration), ON (enables migration for all but explicitly placed data using PAGE_PLACE or a data distribution directive), or ALL_ON (enables migration for all data).

Default: OFF.

Controls the aggressiveness level of automatic page migration. This environment variable must be set to an integer value between 0 (most conservative setting) and 100 (most aggressive). Specifying 0 disables this feature.

Default: 100.

Locks each thread to the corresponding CPU. This environment variable is not set by default.

When set to OFF, disables nonuniform memory access (NUMA) calls. This can be used, for example, to allocate pages from a particular memory.

On Origin series systems, _DSM_OFF is set to ON by default.

Allocates memory for all stack, data, and text segments. Values can be FIRST_TOUCH (specifies first-touch data placement) or ROUND_ROBIN (specifies round-robin data allocation.)

Default: ROUND_ROBIN.

Specifies the number of processors to use per memory module. Must be set to an integer value. To use only one processor per memory module, set this environment variable to 1.

Specifies round-robin data allocation across memories rather than first-touch, for all of stack, data, and text segments.

When set, writes messages to stdout about parameters used during execution to stdout.

Controls how a thread waits for a synchronization event, such as a lock or a barrier. Values can be SPIN (specifies that a thread wait in a loop until the synchronization event succeeds) or YIELD (specifies that a waiting thread should spin for a while and invokes sginap(2), which surrenders the CPU to another waiting process, if any).

Default: YIELD.

Specifies the type of scheduling to use on PARALLEL DO loops with scheduling specified as RUNTIME.

The defaults are the same as those for the DOACROSS directive clauses. If neither environment variable is set, SIMPLE scheduling is assumed. If MP_SCHEDTYPE is set and CHUNK is not set, a CHUNK of 1 is assumed. If CHUNK is set, but MP_SCHEDTYPE is not set, DYNAMIC scheduling is assumed.

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Note: The MP_SCHEDTYPE and CHUNK environment variables are outmoded. The preferred alternative is the OMP_SCHEDULE environment variable.

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Acts as an implicit call to MP_SET_NUMTHREADS(3f), MP_BLOCKTIME(3f), and MP_SETUP(3f) (respectively).

The MP_SET_NUMTHREADS environment variable determines the number of processors across which an array is distributed during program execution, regardless of the number of processors physically present on the machine. MP_BLOCKTIME accepts an integer value. MP_SETUP accepts no values.

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Note: The MP_SET_NUMTHREADS and NUM_THREADS environment variables are outmoded. The preferred alternative is the OMP_NUM_THREADS environment variable.

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Controls simple scheduling of parallel loops. Values can be EQUAL or BLOCK. If you are using distributed arrays, the default is BLOCK. For all other cases, the default is EQUAL. The critical path (that is, the largest piece of the iteration space) is the same in either case.

Controls the stack size of slave processes. As its value, it accepts an integer number that indicates the desired stack size, in bytes. The default is 16 Mbytes (4 Mbytes for greater than 64 threads). Slave processes allocate their local data only onto their stacks. Shared data, even if allocated on the master's stack, is not counted.

Controls stack overflow checking. In a multi-threaded program (for example, one using OpenMP constructs) the MP runtime system automatically detects and reports stack overflow errors at runtime. When stack overflow errors are encountered, you can use the MP_SLAVE_STACKSIZE environment variable or the MP_SET_SLAVE_STACKSIZE library routine to request larger stacks for the parallel threads.

The MP_SLAVE_STACKSIZE environment variable and the MP_SET_SLAVE_STACKSIZE library routine affect the allocation of stack space for parallel threads. If this effect is not desired, it can be be disabled by setting the MP_STACK_OVERFLOW environment variable to OFF. By default, this environment variable is set to ON.

Enables an additional, asynchronous process that monitors the system load. This environment variable may be useful on a system with long-running jobs and varying workloads.

The process that is enabled allows you to vary the number of threads during execution of some jobs. When idle processors exist, the number of threads is increased, up to the maximum specified by MP_SET_NUMTHREADS. When the system load increases, the number of threads is decreased, possibly to as few as one. Note that the number of threads being used is adjusted only at the start of a parallel region (for example, at a DOACROSS directive); it is not adjusted within a parallel region. Using this environment variable can improve overall system throughput. By avoiding excessive concurrency, this feature can reduce delays at synchronization points within a single application.

These environment variables are on by default.

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Note: The MP_SUGNUMTHD and MPC_SUGNUMTHD environment variables are outmoded. The preferred alternative is the OMP_DYNAMIC environment variable.

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Limits the effect of MP_SUGNUMTHD. These environment variables accept an integer value between 1 and the value of MP_SET_NUMTHREADS. When these environment variables are set, the number of processors is not lowered below the MP_SUGNUMTHD_MIN setting and it is not increased beyond the MP_SUGNUMTHD_MAX setting.

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Note: These environment variables are outmoded.

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Determines whether or not the system writes informational messages to stderr whenever the process changes the number of threads in use.

The compiler interprets library calls to MP_NUMTHREADS(3f) and MP_SET_NUMTHREADS(3f) as a sign that the application depends on the number of threads in use, and the number is frozen upon encountering either of these calls. If MP_SUGNUMTHD_VERBOSE is set, a message to that effect is written to stderr. By default, this environment variable is not set.

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Note: The MP_SUGNUMTHD_VERBOSE environment variable is outmoded. The preferred alternative is the _DSM_VERBOSE environment variable.

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Controls the use of gang scheduling, which is enabled by default. To disable gang scheduling, set this environment variable to OFF. By default, this environment variable is not set.

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Note: The MPC_GANG environment variable is outmoded.

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Specifies the desired page size for each of the stack, data, and text segments. The default page size is 16 Kbytes on IRIX 6.4 and later systems; the default is 4 Kbytes on systems running previous IRIX revisions. These environment variables accept an integer value that represents the desired size in Kbytes. Typical values for this environment variable are 4, 16, or 64. Your operating system may not be able to accommodate larger values. If unsuitable values are specified, the system may adjust your page size to be lower than requested.

Specifies aspects of the aioinit structure. This structure contains the following fields: aio_locks, aio_numusers, and aio_threads. These environment variables alter the values used for these fields. For more information on using these environment variables, see AIO_SGI_INIT(3) man page.

Names a file to which statistics are written by the event FFIO layer.

Specifies the location of the assign environment information. Use FILENV to assign a file name to store the assign information or to specify that it be stored in the process environment.

Specifies the a path or a colon-separated list of paths designating where the compiler is to look for the compiler.defaults file.

Controls the Fortran-to-C interface. As a value for this environment variable, specify options to the mkf2c(1) command.

Determines restrictions for various data types.

Controls whether the compiler aborts execution if a bounds check fails.

The f90 -C option performs array bounds checking. By default, execution continues even if the bounds check fails. To cause the compiler to abort on a failed bounds check, set the F90_BOUNDS_CHECK_ABORT environment variable to YES.

Specifies the default library search path. This differs depending on the ABI being used. For more information on these environment variables, see rld(5).

Controls the number of digits of precision printed by list-directed output.

Affects interactions with the message system. For more information, see catopen(3c).

Specifies the Application Binary Interface (ABI) used during compilation. This environment variable can be used to change the default ABI. Specify -o32, -n32, or -64 as values.

Specifies the default C compile mode. This environment variable can be set to any one of ansi, cckr (cc only), or xansi, and is interpreted as an option before any other options specified on the command line.

Specifies a path for temporary files. When set, the value used is the directory in which the system places temporary files, rather than the default, /tmp.

Controls the handling and classifying of floating-point exceptions and substitutes new values. It also provides a mechanism to count, trace, exit, or abort on enabled exceptions. The -TENV:check_div option on the command line inserts checks for divide by zero and for overflow. See FSIGFPE(3f) for information on HANDLE_FSIGFPES, which performs a function similar to that of this environment variable.

Specifies that compilation should proceed according to X/Open XPG4 specifications. If set, cc or f77 (c89 or fort77, as they are known under XPG4, respectively) operates in conformance with the X/Open XPG4 specifications. The options and the command line behavior may differ in accordance to the XPG4 standards.

Sets the default size of the fractional field using real formating specifications.

Sets the environment for new 32-bit compilation.

Sets the environment for 64-bit compilation.

Sets the environment for old 32-bit compilation.