Performance Metrics of Tiers

The previous post explained the software architecture and its types. Since each tier has different roles and operations hence the performance matrices are also different. Below is a list of certain mandatory performance metrics for each of the tiers which should be monitored during the performance test.

Client Tier

Since there is a need for better application performance in any client machine application a quick result is obtained. Generally, the front end takes the maximum time to load. Thus reducing the front-end loading time of the application by 40% can increase the performance of the application. Some of the client-tier performance testing metrics are as follows:

  • TCP connection time
  • HTML resources load time
  • CSS files load time
  • Images load time
  • JavaScript file load time
  • HTTP response time
  • HTTP response status

Web Tier

Web Tier metrics provide useful information on web server performance. It gives information on the usage of resources on the web server during the execution of performance tests. The web server metrics depend on the type of web server that is being used in the production environment. The web server performance metrics for Microsoft IIS are:

  • Percent Disk Time
  • Cache Hit length
  • Request Queued
  • Number of HTTP connections
  • Bytes sent and received per second
  • Private bytes
  • Error 404 (not found) bytes 
  • CPU utilization
  • Memory utilization
  • Disk utilization

Apache Web Server counters:

  • CPU Load
  • Request per sec
  • Bytes per sec
  • Bytes per request
  • Busy Workers
  • Idle Workers

Application tier

Application Tier is the backbone of application in case of highly complex business applications. Some of the application servers are Web logic, Microsoft .Net, Apache TomCat, Web Sphere, J Boss etc. Most of the application activities are performed on the application server. Hence application server counters need attention during performance testing. The application server has the following performance metrics:

  • Connection Time
  • Connection Wait Time
  • Total Threads
  • Memory Use
  • Total Memory
  • Active Transactions
  • Transactions suspended
  • Rolled Back transactions
  • Timeouts
  • Servlet Errors
  • CPU utilization
  • Memory utilization
  • Disk utilization

Database tier

At this tier, we have to look for queries for which execution time is high and the presence of any deadlocks. The parameters for database server performance metrics are:

  • CPU Utilization
  • Memory Utilization
  • Disk utilization
  • Query throughput
  • Query execution performance
  • Queue Length
  • Connections
  • Buffer pool usage
  • Pages per second
  • Processor Time

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