Sets a threshold for the auto-parallelization of loops.
Windows: Optimization
> Threshold For Auto-Parallelization
Linux: None
IA-32, IntelŪ EM64T, IntelŪ ItaniumŪ architecture
| Linux: | -par-threshold[n] |
| Windows: | /Qpar-threshold[[:]n] |
| n | Is an integer whose value is the threshold for the auto-parallelization
of loops. Possible values are 0 through 100. If n is 0, loops get auto-parallelized always, regardless of computation work volume. If n is 100, loops get auto-parallelized when performance gains are predicted based on the compiler analysis data. Loops get auto-parallelized only if profitable parallel execution is almost certain. The intermediate 1 to 99 values represent the percentage probability for profitable speed-up. For example, n=50 directs the compiler to parallelize only if there is a 50% probability of the code speeding up if executed in parallel. |
| -par-threshold100 or /Qpar-threshold100 |
Loops get auto-parallelized only if profitable parallel execution is almost certain. This is also the default if you do not specify n. |
This option sets a threshold for the auto-parallelization of loops based on the probability of profitable execution of the loop in parallel.
This option is useful for loops whose computation work volume cannot be determined at compile-time. The threshold is usually relevant when the loop trip count is unknown at compile-time.
The compiler applies a heuristic that tries to balance the overhead of creating multiple threads versus the amount of work available to be shared amongst the threads.
Linux: -par_threshold
Windows: /Qpar_threshold
Optimizing Applications:
Auto-Parallelization Overview
Auto-Parallelization: Enabling, Options, Directives, and Environment Variables
Auto-Parallelization: Threshold Control and Diagnostics