Show Delta

Show_delta is a tool available in the Linux kernel tree for showing the time (delta) between kernel messages, based on their printk timestamps. You can find the tool in the kernel source tree in the 'scripts' directory. Or online here: https://github.com/torvalds/linux/blob/master/scripts/show_delta

For examples of show_delta usage see: Printk_Times#show_delta_results

This tool is useful for finding operations in the kernel that are taking a long time. Of course, it relies on there being suitable printk messages emitted at the beginning and end of an operation, to serve as markers for regions of interest.

version 2.0

Tim Bird has recently been adding additional functionality to show_delta to support reporting the duration for regions (or sets of lines), with eventual plan to integrate this with a selftest for boot times. This work should show up on the kernel mailing list shortly (Nov. 2024?)