zInsight: Visualizing Complex Traces from System z

zInsight is a visual tool for debugging and performance analysis on System z. It helps users explore, navigate and understand the zOS system trace. Inspecting the system trace with traditional low bandwidth textual tools can be a daunting task since they may contain hundreds of thousands of events. zInsight uses techniques to make inexperienced users more effective and experienced analysts more productive.

 

• The user can easily see a large number of events on one screen rather than scrolling through tens of thousands of screens of text data. Color, position, and intensity are used to create visual patterns in the trace which reflect underlying patterns in the data.
• The analyst can isolate interesting parts of the trace, e.g. execution in a specific process, thread, or physical processor. A statistics view linked to the events visualization allows the user to sort and quantify events by different criteria so that comparisons with other traces can be made and hot spots are revealed.
• A context sequence graph shows control flow. This function can be used to understand which execution flows resulted in a certain type of event.

The speaker will demonstrate the use of zInsight on three actual situations:

1. a problem where spinlock contention was slowing down an application
2. a trace table sweep to find anomalies in an application
3. using the context sequence graph to capture the control flow of a hot spot in a large trace.

Tracks: Applications Programming and z/OS Systems Programming