tslog4

Usage

Overview

tslog is a boot-time event tracing facility. It is suitable for tracing recursive events based on function entries and exits. Its purpose is to ease pinpointing and reducing the overall FreeBSD boot time by generating detailed timing information.

tslog is able to trace the boot loader, kernel initialization, and userland processes.

In userland, it records the following details for each process ID:

• The timestamp of the fork(2) which creates the given process ID and the parent process ID.

• The path passed to execve(2), if any.

• The first path resolved by namei(9), if any.

• The timestamp of the exit(3) which terminates the process.

Sysctl variables

The following sysctl(8) variables are available:

debug.tslog

Dump the tslog buffer of recorded loader and kernel event timestamps.

debug.tslog_user

Dump the tslog buffer of recorded userland event timestamps.

Flamegraphs

The tslog buffer dumps can be used to generate flamegraphs of the FreeBSD boot process for visual analysis. See https://github.com/cperciva/freebsd-boot-profiling for more information.