.\"
.\" Copyright (c) 2025 Mateusz Piotrowski <0mp@FreeBSD.org>
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.Dd November 4, 2025
.Dt DTRACE_CALLOUT_EXECUTE 4
.Os
.Sh NAME
.Nm dtrace_callout_execute
.Nd a DTrace provider for the callout API
.Sh SYNOPSIS
.Nm callout_execute Ns Cm :kernel::callout_start
.Nm callout_execute Ns Cm :kernel::callout_end
.Sh DESCRIPTION
The
.Nm callout_execute
provider allows for tracing the
.Xr callout 9
mechanism.
.Pp
The
.Nm callout_execute Ns Cm :kernel::callout_start
probe fires just before a callout.
.Pp
The
.Nm callout_execute Ns Cm :kernel::callout_end
probe fires right after a callout.
.Pp
The only argument to the
.Nm callout_execute
probes,
.Fa args[0] ,
is a callout handler
.Ft struct callout *
of the invoked callout.
.Sh EXAMPLES
.Ss Example 1: Graph of Callout Execution Time
The following
.Xr d 7
script generates a distribution graph of
.Xr callout 9
execution times:
.Bd -literal -offset 2n
callout_execute:::callout_start
{
    self->cstart = timestamp;
}

callout_execute:::callout_end
{
    @length = quantize(timestamp - self->cstart);
}
.Ed
.Sh SEE ALSO
.Xr dtrace 1 ,
.Xr tracing 7 ,
.Xr callout 9 ,
.Xr SDT 9
.Sh AUTHORS
.An -nosplit
The
.Nm callout_execute
provider was written by
.An Robert N. M. Watson Aq Mt rwatson@FreeBSD.org .
.Pp
This manual page was written by
.An Mateusz Piotrowski Aq Mt 0mp@FreeBSD.org .