usl (version 1.2.1)

peak.scalability: Peak scalability value of a USL model

Description

Calculate the point of peak scalability for a specific model.

Usage

## S3 method for class 'USL':
peak.scalability(object, sigma, kappa)

Arguments

object

A USL object.

sigma

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

kappa

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

Value

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

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 sigma or kappa 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.

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, scalability

Examples

require(usl)

data(raytracer)

peak.scalability(usl(throughput ~ processors, raytracer))
## Peak scalability will be reached just below 450 processors