peak.scalability,USL-method {usl}

Point of peak scalability of a USL model

Description

Calculate the point of peak scalability for a specific model.

Usage

## S4 method for signature 'USL'
peak.scalability(object, alpha, beta, gamma)

Arguments

object

A USL object.

alpha

Optional parameter to be used for evaluation instead of the parameter computed for the model.

beta

Optional parameter to be used for evaluation instead of the parameter computed for the model.

gamma

Optional parameter to be used for evaluation instead of the parameter computed for the model.

Details

The peak scalability is the point where the throughput of the system starts to go retrograde, i.e., starts to decrease with increasing load.

The parameters alpha, beta and gamma are useful to do a what-if analysis. Setting these parameters override the model parameters and show how the system would behave with a different contention or coherency delay parameter.

See formula (4.33) in Guerilla Capacity Planning.

This function accepts an argument for gamma although the value is not required to perform the calculation. This is on purpose to provide a coherent interface.

Value

A numeric value for the point where peak scalability will be reached.

References

Neil J. Gunther. Guerrilla Capacity Planning: A Tactical Approach to Planning for Highly Scalable Applications and Services. Springer, Heidelberg, Germany, 1st edition, 2007.

See Also

usl, optimal.scalability,USL-method limit.scalability,USL-method

Examples

require(usl)

data(specsdm91)

peak.scalability(usl(throughput ~ load, specsdm91))
## Peak scalability will be reached at about 96 virtual users