PerOpteryx/Tactics Case Study

Aus SDQ-Wiki
Zur Navigation springen Zur Suche springen

On this page, the PCM model of the BRS system for the case study will be presented.

BRS System

The system under study is the so-called business reporting system (BRS). It allows users to retrieve statistical reports about business processes from a database and is loosely based on a real system.

Description

System Model

The figure below shows the assembly of components in the system.

System model.

Allocation Model

The components are initially allocated to four different servers, as shown in the figure below.

Allocation model.

RDSEFFs (Behavioural Models)

Besides components and servers, the PCM instance of the BRS contains RDSEFFs as behavioural descriptions. The figures below contain some examples. Double-click on a thumbnail to see the complete RDSEFF. You can inspect all behaviour descriptions when opening the models linked below.

Usage Model

The case study analyses an open workload usage scenario, with an arrival rate of 0.5 users per second. Users access multiple services of the system per interaction. The usage model is shown below.

Usage model.

Cost Model

The BRS servers are annotated with costs depending on the chosen processing rate. For the cost model, we analysed Intel's CPU price list[1]. Similar to [2], we fitted a power function to this data, so that the resulting cost model is cost = 0.7665 procRate^{6.2539} with coefficient of determination R^2 = 0.965 and procRate being the processing rate of a server's CPU. The initial cost of the servers is 618 units. The cost model is shown below.

Cost model.

Degrees of Freedom

18 degrees of freedom have been considered:

  • Processing rate of server S1, ranging from 0.75 GHz to 3 GHz
  • Processing rate of server S2, ranging from 0.75 GHz to 3 GHz
  • Processing rate of server S3, ranging from 0.75 GHz to 3 GHz
  • Processing rate of server S4, ranging from 0.75 GHz to 3 GHz
  • Processing rate of server S5, ranging from 0.75 GHz to 3 GHz
  • Processing rate of server S6, ranging from 0.75 GHz to 3 GHz
  • Processing rate of server S7, ranging from 0.75 GHz to 3 GHz
  • Processing rate of server S8, ranging from 0.75 GHz to 3 GHz
  • Processing rate of server S9, ranging from 0.75 GHz to 3 GHz
  • Allocation of the Webserver component, to one of the server S1 to S9
  • Allocation of the Scheduler component, to one of the server S1 to S9
  • Allocation of the UserManagement component, to one of the server S1 to S9
  • Allocation of the GraphicReporting component, to one of the server S1 to S9
  • Allocation of the OnlineReporting component, to one of the server S1 to S9
  • Allocation of the CoreGraphicEngine component, to one of the server S1 to S9
  • Allocation of the CoreOnlineEngine component, to one of the server S1 to S9
  • Allocation of the CacheInfo component, to one of the server S1 to S9
  • Allocation of the Database component, to one of the server S1 to S9

The degrees of freedom are specified in the designdecision model shown below. Note that the processing rate has been specified in 1/3 GHz. The figure shows the editor window to change the allocation of the Webserver component.

System model.

PCM Models

You can download the Datei:PCM3.3 BRS Optimisation.zip and open it with our current nightly build of the PCM tools. See PCM_3.3 for details how to install and use the PCM. You find a Run Configuration entry named PCM Design Space Exploration for PerOpteryx, where you can enter the settings for an optimisation run. You can also inspect the model files with an XML editor, if you like. See PerOpteryx for more information on the evolutionary optimisation tool.

The SVN is located at https://sdqweb.ipd.uka.de/svn/code/Palladio.Examples/trunk/PCM3.3_BRS_Optimisation_Heuristics

Screenshots BRS

Results of the Optimisation Runs

The resulting Pareto fronts of all runs after 200 iterations can be found in this Excel 2007 file: Datei:PerOpteryx Results BRS System.zip.

The file is structured as follows:

  • The sheet "Graph All Pareto fronts (T)" contains the Pareto fronts of all runs with tactics
  • The sheet "Graph All Pareto fronts (B)" contains the Pareto fronts of all runs without tactics
  • The sheet "Graph all Pareto fronts" contains two diagrams that compare the results with tactics and without tactics. One diagram shows the runs without tactics in the foreground (see also image below), the other one shows the runs with tactics in the foreground.

The image below shows the comparison of all Pareto fronts, with the results of runs B orange in foreground. We observe that the runs with tactics (green runs) are consistently better, especially in the region of low costs. See the Excel sheet below for a version with the tactics run in the foreground.

Comparison of all Pareto fronts, runs B in foreground.

ABB system

Results of the Optimisation Runs

The resulting Pareto fronts of all runs after 200 iterations can be found in this Excel 2007 file: Datei:PerOpteryx Results ABB System.zip.

The file is structured as follows:

  • The sheet "Graph All Pareto fronts (T)" contains the Pareto fronts of all runs with tactics
  • The sheet "data of all runs (T)" contains an excerpt of the set of all result candidates (union of the Pareto fronts of all tactics runs) showing the costs, mean response time, and the processing rates of all servers as an example for the genome.
  • The sheet "Graph All Pareto fronts (B)" contains the Pareto fronts of all runs without tactics
  • The sheet "Graph all Pareto fronts" contains two diagrams that compare the results with tactics and without tactics. One diagram shows the runs without tactics in the foreground (see also image below), the other one shows the runs with tactics in the foreground.

The image below shows the comparison of all Pareto fronts, with the results of runs B orange in foreground. We observe that the runs with tactics (green runs) are consistently better, especially in the region of low costs. See the Excel sheet below for a version with the tactics run in the foreground.

Comparison of all Pareto fronts, runs B in foreground.

Running Example

PCM Models

You can download the Datei:PCM3.3 SimpleExample.zip and open it with our current nightly build of the PCM tools. See PCM_3.3 for details how to install and use the PCM. You find a Run Configuration entry named PCM Design Space Exploration for PerOpteryx. You can also inspect the model files with an XML editor, if you like. See PerOpteryx for more information on the evolutionary optimisation tool.

The SVN is located at https://sdqweb.ipd.uka.de/svn/code/Palladio.Examples/trunk/PCM3.3_SimpleHeuristicsExample

Screenshots Running Example

References

  1. Intel Corporation. Intel processor price list, effective feb 8th, 2010. http://www.intc.com/priceList.cfm, 2010. last visit March 10th, 2010.
  2. H. Li, G. Casale, and T. Ellahi. Sla-driven planning and optimization of enterprise applications. In Proc. of WOSP/SIPEW, pages 117--128. ACM, 2010.