Response Time Histogram

The Response Time Histogram displays response times for selected servers.

To view the histogram, select ANALYZE > Graphs > Statistics > Histogram.

The histogram consists of 10 individual bars.

Each bar represents the percentage of replies within a given milliseconds interval.

This way you can very quickly find out if a particular server is potentially overloaded—like the blue one in the example image.

Tip

In the example, we use the histogram to spot a potentially overloaded server. However, the main benefit of the histogram is that it helps you verify if a high average response time is caused by a major or a minor ratio of the total requests. This in turn can help you determine whether a high average response time is really a problem.

Important

How can a high average response time not be a problem?

If a high average response time is caused by a few responses in the 2000-500000 milliseconds interval while the majority of responses are in the 0-10 milliseconds interval, the high average may not be a problem. This of course also depends on your type of organization, which types of applications and servers you run, how business-critical your applications are, etc.

• Servers: Select which servers or server groups you want to base your histogram on. Server groups are enclosed in <>. You can only select server groups and monitored servers. See Server Lists for details about monitored servers.

Tip

Select multiple servers and server groups by pressing the CTRL key while selecting the servers.

• Agents: Select the group of computers you want to base your histogram on. Super groups, that is groups of groups, are enclosed in <>.
• Interval: Select the period of time that the graph should cover. If the predefined intervals don’t suit you, select Custom to Custom Time Periods on Graphs.
• Ports: Select which port or port group you want to base your histogram on. Port groups are enclosed in <>. You can only select port groups and monitored ports. See Port Lists for details about monitored ports.