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freebsd/usr.sbin/kgmon/kgmon.8
Bruce Evans 912e603778 Implemented non-statistical kernel profiling. This is based on
looking at a high resolution clock for each of the following events:
function call, function return, interrupt entry, interrupt exit,
and interesting branches.  The differences between the times of
these events are added at appropriate places in a ordinary histogram
(as if very fast statistical profiling sampled the pc at those
places) so that ordinary gprof can be used to analyze the times.

gmon.h:
Histogram counters need to be 4 bytes for microsecond resolutions.
They will need to be larger for the 586 clock.
The comments were vax-centric and wrong even on vaxes.  Does anyone
disagree?

gprof4.c:
The standard gprof should support counters of all integral sizes
and the size of the counter should be in the gmon header.  This
hack will do until then.  (Use gprof4 -u to examine the results
of non-statistical profiling.)

config/*:
Non-statistical profiling is configured with `config -pp'.
`config -p' still gives ordinary profiling.

kgmon/*:
Non-statistical profiling is enabled with `kgmon -B'.  `kgmon -b'
still enables ordinary profiling (and distables non-statistical
profiling) if non-statistical profiling is configured.
1995-12-29 15:30:05 +00:00

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3.9 KiB
Groff

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.\" @(#)kgmon.8 8.1 (Berkeley) 6/6/93
.\"
.Dd June 6, 1993
.Dt KGMON 8
.Os BSD 4.2
.Sh NAME
.Nm kgmon
.Nd generate a dump of the operating system's profile buffers
.Sh SYNOPSIS
.Nm kgmon
.Op Fl Bbhpr
.Op Fl M core
.Op Fl N system
.Sh DESCRIPTION
.Nm Kgmon
is a tool used when profiling the operating system.
When no arguments are supplied,
.Nm kgmon
indicates the state of operating system profiling as running,
off, or not configured.
(see
.Xr config 8 )
If the
.Fl p
flag is specified,
.Nm kgmon
extracts profile data from the operating system and produces a
.Pa gmon.out
file suitable for later analysis by
.Xr gprof 1 .
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl B
Resume the collection of high resolution profile data.
.It Fl b
Resume the collection of low resolution profile data.
.It Fl h
Stop the collection of profile data.
.It Fl p
Dump the contents of the profile buffers into a
.Pa gmon.out
file.
.It Fl r
Reset all the profile buffers.
If the
.Fl p
flag is also specified, the
.Pa gmon.out
file is generated before the buffers are reset.
.It Fl M
Extract values associated with the name list from the specified core
instead of the default ``/dev/kmem''.
.It Fl N
Extract the name list from the specified system instead of the
default ``/kernel''.
.El
.Pp
If neither
.Fl B
nor
.Fl b
nor
.Fl h
is specified, the state of profiling collection remains unchanged.
For example, if the
.Fl p
flag is specified and profile data is being collected,
profiling will be momentarily suspended,
the operating system profile buffers will be dumped,
and profiling will be immediately resumed.
.Pp
The profile buffers should be reset when the resolution
of the profile data is changed.
.Sh FILES
.Bl -tag -width /dev/kmemx -compact
.It Pa /kernel
the default system
.It Pa /dev/kmem
the default memory
.El
.Sh SEE ALSO
.Xr gprof 1 ,
.Xr config 8
.Sh DIAGNOSTICS
Users with only read permission on
.Pa /dev/kmem
cannot change the state
of profiling collection.
They can get a
.Pa gmon.out
file with the warning that the data may be
inconsistent if profiling is in progress.
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.2 .