NAME
boottrace – Boot-time, run-time, and shutdown-time tracing facility
SYNOPSIS
#include <sys/boottrace.h>
DESCRIPTION
boottrace is a kernel-userspace interface for capturing trace events during system boot and shutdown (in particular, one-shot events).
Event annotations are present in:
-
the boot and shutdown paths in the kernel
-
some key system utilities( init(8), shutdown(8), reboot(8))
-
rc(8) scripts
boottrace is unconditionally compiled into the kernel and disabled by default.
EVENT TABLES
Events are stored in three event tables: boot-time events, run-time events, and shutdown-time events.
| Table Name | Event Description |
| boot-time events | Boot, kernel initialization, and |
| run-time events | |
| shutdown-time events |
LOADER TUNABLES
Tunables can be set at the loader(8) prompt before booting the kernel or stored in loader.conf(5). boottrace features the following loader tunables:
- kern.boottrace.dotrace_kernel
-
Set to ‘1’ to enable tracing of kernel events. Default: ‘1’ (enabled).
- kern.boottrace.dotrace_user
-
Set to ‘1’ to enable tracing of userspace events. Default: ‘1’ (enabled).
SYSCTL VARIABLES
The following variables are available as both sysctl(8) variables and loader(8) tunables:
- kern.boottrace.boottrace
-
Create a new trace event and write it to the boot-time table.
A new trace event consists of a process name and an event description, separated by a colon (‘:’). If the colon is missing or if the provided string for the process name is empty, the process name is inferred from the invoking process (which is its executable name).
- kern.boottrace.enabled
-
Set to ‘1’ to enable tracing. This is a read-only sysctl(8) variable. Default: ‘0’ (disabled).
- kern.boottrace.log
-
Show the events stored in boot-time and run-time tables. This is an opaque sysctl(8) variable.
- kern.boottrace.runtrace
-
Same as kern.boottrace.boottrace, but write to the run-time table.
- kern.boottrace.shuttrace
-
Same as kern.boottrace.boottrace, but write to the shutdown-time table.
- kern.boottrace.shutdown_trace
-
Log shutdown-time events to the console before the system halts.
- kern.boottrace.shutdown_trace_threshold
-
Set a time threshold for logging shutdown-time events in milliseconds. An event is ignored if the time difference to the previous event is less than the threshold value. Default: ‘0’ (logs all events).
EXAMPLES
Create a new trace event with a process name “foo” and an event description “bar” using sysctl(8):
sysctl kern.boottrace.boottrace="foo:bar"
Here is a sample output of kern.boottrace.log (shortened with “[...]” for readability):
CPU msecs delta process event PID CPUtime IBlks OBlks 0 44872811 0 kernel sysinit 0x2100001 0 0.00 0 0 0 44872812 1 kernel sysinit 0x2110000 0 0.00 0 0 0 44872812 0 kernel sysinit 0x2140000 0 0.00 0 0 [...] 0 44872817 0 kernel sysinit 0x2800000 0 0.00 0 0 0 44873820 1003 kernel sysinit 0x2880000 0 0.00 0 0 0 44873820 0 kernel sysinit 0x2888000 0 0.00 0 0 [...] 1 44875735 0 kernel sysinit 0xfffffff 0 0.00 0 0 1 44875735 0 swapper mi_startup done 0 0.00 0 0 0 44875750 15 init init(8) starting... 1 0.00 0 0 0 44875751 1 init /etc/rc starting... 1 0.00 0 0 0 44875831 80 boottrace /etc/rc.d/rctl start 26 0.00 0 0 1 44875839 8 boottrace /etc/rc.d/rctl done 26 0.00 2 0 [...] 0 44876446 0 boottrace /etc/rc.d/netif start 390 0.00 0 0 1 44881116 4670 boottrace /etc/rc.d/netif done 390 0.12 34 0 [...] 0 44882866 1 boottrace /etc/rc.d/securelevel start 1679 0.00 0 0 0 44882872 6 boottrace /etc/rc.d/securelevel done 1679 0.00 0 0 1 44882879 7 init /etc/rc finished 1 2.22 743 15 Total measured time: 10068 msecs CPU msecs delta process event PID CPUtime IBlks OBlks 1 44882880 0 init multi-user start 1 2.22 743 15 0 44918215 35335 kldload hwpmc.ko: sysinit 0xd800000 1698 0.00 0 0 Total measured time: 35335 msecs
SEE ALSO
HISTORY
NetApp created boottrace to diagnose slow devices and subsystems. Once upstreamed, boottrace was first publicly released with FreeBSD 14.0.
AUTHORS
This manual page was written by Mateusz Piotrowski ⟨[email protected]⟩.