deterministic tuning time limit

Purpose

Deterministic tuning time limit

Description

Sets a deterministic time limit per model and per test set (that is, suite of models) applicable in tuning and measured in ticks.

When this deterministic tuning time limit is set to a finite value, then tuning finds appropriate settings of other CPLEX parameters to minimize the deterministic time of optimization. Furthermore, the tuning process itself is deterministic. In this context, "a finite value" means any value strictly less than 1e+75 (such as the finite value 1e+74).

Interaction with other parameters: nondeterministic tuning time limit

This deterministic time limit on tuning is not compatible with the wall-clock tuning time limit in seconds (CPX_PARAM_TUNINGTILIM, TuningTiLim). Only one of these two parameters can be set to a finite value at a time. Any attempt to set either of these parameters to a finite value while the other is already set to a finite value results in the error CPXERR_PARAM_INCOMPATIBLE from the routine CPXsetdblparam or the method setDblParam (depending on the API you are using).

Finite values of tuning time limits

If this deterministic time limit on tuning is set to a finite value, then the tuning process itself is deterministic, and CPLEX recommends appropriate parameter settings to minimize the deterministic optimization time.

If the wall-clock tuning time limit in seconds (CPX_PARAM_TUNINGTILIM, TuningTiLim) is set to a finite value, then the tuning process itself is nondeterministic, and it recommends appropriate parameter settings to minimize the wall-clock optimization time.

The default value of this parameter is 1e+75 (effectively, infinite).

Likewise, the default value of the wall-clock tuning time limit in seconds (CPX_PARAM_TUNINGTILIM, TuningTiLim) is also 1e+75 (effectively, infinite).

If this parameter is set at its default value 1e+75, and if the tuning time limit in seconds (CPX_PARAM_TUNINGTILIM, TuningTiLim) is also set at its default value 1e+75, then the combination is equivalent to setting the deterministic tuning time limit to 10 000 000 ticks. Consequently, these combined default settings make the tuning process deterministic, and CPLEX recommends settings to minimize the deterministic optimization time.

Unlimited time per model

If you want to run a tuning session with unlimited time per model, then set one of the tuning time limit parameters (either wall-clock tuning time limit in seconds (CPX_PARAM_TUNINGTILIM, TuningTiLim) or deterministic tuning time limit (CPX_PARAM_TUNINGDETTILIM, TuningDetTiLim) to a very large value that is strictly less than 1e+75 (for example, 1e+74). If you set CPX_PARAM_TUNINGDETTILIM, TuningDetTiLim to a finite value, then the tuning process will be deterministic. If you set CPX_PARAM_TUNINGTILIM, TuningTiLim to a finite value, then the tuning process will be nondeterministic.

Ticks

A tick is a unit to measure work done deterministically. The length of a deterministic tick may vary by platform. Nevertheless, ticks are normally consistent measures for a given platform (combination of hardware and software) carrying the same load. In other words, the correspondence of ticks to clock time depends on the hardware, software, and the current load of the machine. For the same platform and same load, the ratio of ticks per second stays roughly constant, independent of the model solved. However, for very short optimization runs, the variation of this ratio is typically high.

Values

Any nonnegative number; default: 1e+75 ticks.

See also

optimizer time limit in seconds

deterministic time limit

tuning time limit in seconds