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BOOTTRACE(4) Kernel Interfaces Manual BOOTTRACE(4) 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 rc(8) execu- tion; until init(8) transitions into multi- user mode run-time events From when the system has completed booting (including rc(8) execution) and init(8) transitions to multi-user mode until the beginning of shutdown procedures shutdown-time events After initialization of a shutdown, a reboot, or a kernel panic 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 de- scription, 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 ta- ble. 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 mil- liseconds. 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 de- scription "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 tslog(4), boottrace(8), sysctl(8) 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 <0mp@FreeBSD.org>. FreeBSD 14.3 July 1, 2022 BOOTTRACE(4)
NAME | SYNOPSIS | DESCRIPTION | EVENT TABLES | LOADER TUNABLES | SYSCTL VARIABLES | EXAMPLES | SEE ALSO | HISTORY | AUTHORS
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