Summary

It would be useful to have a tool for helping engineers to visualize and understand I/O traces from WiredTiger, at both file level and at the device level, so that we can better understand and optimize its I/O patterns.

Capturing traces

We can already capture I/O traces both at the file level and at the device level as follows.

At the file level, we can enable DEBUG_2 level logging for WT_VERB_READ and WT_VERB_WRITE, e.g., by running the following before the workload:

export WIREDTIGER_CONFIG="verbose=[read:2,write:2]"

To capture traces at the device level, we can use utility such as blktrace.
 
Using the traces

The generated traces are very large, so we need a program that can efficiently process and visualize them.