plot,USL-method {usl}

Plot the scalability function from a USL model

Description

Create a line plot for the scalability functionh of a Universal Scalability Law model.

Usage

## S4 method for signature 'USL'
plot(
  x,
  from = NULL,
  to = NULL,
  xlab = NULL,
  ylab = NULL,
  bounds = FALSE,
  alpha,
  beta,
  ...
)

Arguments

x

The USL object to plot.

from

The start of the range over which the scalability function will be plotted.

to

The end of the range over which the scalability function will be plotted.

xlab

A title for the x axis: see title.

ylab

A title for the y axis: see title.

bounds

Add the bounds of scalability to the plot. This always includes the linear scalability bound for low loads. If the contention coefficient alpha is a positive number, then the Amdahl asymptote for high loads will also be plotted. If the coherency coefficient beta is also a positive number, then the point of peak scalability will also be indicated. All bounds are show using dotted lines. Some bounds might not be shown using the default plot area. In this case the parameter ylim can be used to increase the visible plot area and include all bounds in the output.

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.

...

Other graphical parameters passed to plot (see par, plot.function).

Details

plot creates a plot of the scalability function for the model represented by the argument x.

If from is not specified then the range starts at the minimum value given to define the model. An unspecified value for to will lead to plot ending at the maximum value from the model. For add = TRUE the defaults are taken from the limits of the previous plot.

xlab and ylab can be used to set the axis titles. The defaults are the names of the regressor and response variables used in the model.

If the parameter bounds is set to TRUE then the plot also shows dotted lines for the theoretical bounds of scalability. These are the linear scalability for small loads and the Amdahl asymptote for the limit of scalability as load approaches infinity.

The parameters alpha or beta 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 Also

usl, plot.function

Examples

require(usl)

data(specsdm91)

## Plot result from USL model for demo dataset
plot(usl(throughput ~ load, specsdm91), bounds = TRUE, ylim = c(0, 3500))