freebsd-dev/usr.sbin/pmcstat/pmcstat.8

.\" Copyright (c) 2003 Joseph Koshy.  All rights reserved.
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.\" This software is provided by Joseph Koshy ``as is'' and
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.\" $FreeBSD$
.\"
.Dd July 1, 2005
.Os
.Dt PMCSTAT 8
.Sh NAME
.Nm pmcstat
.Nd "performance measurement with performance monitoring hardware"
.Sh SYNOPSIS
.Nm
.Op Fl C
.Op Fl D Ar pathname
.Op Fl E
.Op Fl O Ar logfilename
.Op Fl P Ar event-spec
.Op Fl R Ar logfilename
.Op Fl S Ar event-spec
.Op Fl W
.Op Fl c Ar cpu
.Op Fl d
.Op Fl g
.Op Fl k Ar kernelfile
.Op Fl n Ar rate
.Op Fl o Ar outputfile
.Op Fl p Ar event-spec
.Op Fl s Ar event-spec
.Op Fl t Ar pid
.Op Fl w Ar secs
.Op Ar command Op Ar args
.Sh DESCRIPTION
The
.Nm
utility measures system performance using the facilities provided by
.Xr hwpmc 4 .
.Pp
The
.Nm
utility can measure both hardware events seen by the system as a
whole, and those seen when a specified process is executing on the
system's CPUs.
If a specific process is being targeted (for example,
if the
.Fl t Ar pid
option is specified, or if a command line is specified using
.Ar command ) ,
then measurement occurs till the target process exits or
the
.Nm
utility is interrupted by the user.
If a specific process is not targeted for measurement, then
.Nm
will perform system-wide measurements till interrupted by the
user.
.Pp
A given invocation of
.Nm
can mix allocations of system-mode and process-mode PMCs, of both
counting and sampling flavors.
The values of all counting PMCs are printed in human readable form
at regular intervals by
.Nm .
The output of sampling PMCs may be configured to go to a log file for
subsequent offline analysis, or, at the expense of greater
overhead, may be configured to be printed in text form on the fly.
.Pp
Hardware events to measure are specified to
.Nm
using event specifier strings
.Ar event-spec .
The syntax of these event specifiers is machine dependent and is
documented in
.Xr pmc 3 .
.Pp
A process-mode PMC may be configured to be inheritable by the target
process' current and future children.
.Sh OPTIONS
The following options are available:
.Bl -tag -width indent
.It Fl C
Toggle between showing cumulative or incremental counts for
subsequent counting mode PMCs specified on the command line.
The default is to show incremental counts.
.It Fl D Ar pathname
Create files with per-program samples in the directory named
by
.Ar pathname .
The default is to create these files in the current directory.
.It Fl E
Toggle showing per-process counts at the time a tracked process
exits for subsequent process-mode PMCs specified on the command line.
This option is useful for mapping the performance characteristics of a
complex pipeline of processes when used in conjunction with the
.Fl d
option.
The default is to not to enable per-process tracking.
.It Fl O Ar logfilename
Send logging output to file
.Ar logfilename .
If this option is not specified and one of the logging options
is requested, then
.Nm
will print a textual form of the logged events to the configured
output file.
.It Fl P Ar event-spec
Allocate a process mode sampling PMC measuring hardware events
specified in
.Ar event-spec .
.It Fl R Ar logfilename
Perform offline analysis using sampling data in file
.Ar logfilename .
.It Fl S Ar event-spec
Allocate a system mode sampling PMC measuring hardware events
specified in
.Ar event-spec .
.It Fl W
Toggle logging the incremental counts seen by the threads of a
tracked process each time they are scheduled on a CPU.
This is an experimental feature intended to help analyse the
dynamic behaviour of processes in the system.
It may incur substantial overhead if enabled.
The default is for this feature to be disabled.
.It Fl c Ar cpu
Set the cpu for subsequent system mode PMCs specified on the
command line to
.Ar cpu .
The default is to allocate system mode PMCs on CPU zero.
.It Fl d
Toggle between process mode PMCs measuring events for the target
process' current and future children or only measuring events for
the target process.
The default is to measure events for the target process alone.
.It Fl g
Produce flat execution profiles in a format compatible with
.Xr gprof 1 .
A separate profile file is generated for each executable object
encountered.
Profile files are placed in sub-directories named by their PMC
event name.
.It Fl k Ar kernelfile
Set the pathname of the kernel to argument
.Ar kernelfile .
The default is
.Pa /boot/kernel/kernel .
.It Fl n Ar rate
Set the default sampling rate for subsequent sampling mode
PMCs specified on the command line.
The default is to configure PMCs to sample the CPU's instruction
pointer every 65536 events.
.It Fl o Ar outputfile
Send counter readings and textual representations of logged data
to file
.Ar outputfile .
The default is to send output to
.Pa stderr .
.It Fl p Ar event-spec
Allocate a process mode counting PMC measuring hardware events
specified in
.Ar event-spec .
.It Fl s Ar event-spec
Allocate a system mode counting PMC measuring hardware events
specified in
.Ar event-spec .
.It Fl t Ar pid
Attach all process mode PMCs allocated to the process with PID
.Ar pid .
The option is not allowed in conjunction with specifying a
command using
.Ar command .
.It Fl w Ar secs
Print the values of all counting mode PMCs every
.Ar secs
seconds.
The argument
.Ar secs
may be a fractional value.
The default interval is 5 seconds.
.El
.Pp
If
.Ar command
is specified, it is executed using
.Xr execvp 3 .
.Sh EXAMPLES
To perform system-wide statistical sampling on an AMD Athlon CPU with
samples taken every 32768 instruction retirals and data being sampled
to file
.Pa sample.stat ,
use:
.Dl "pmcstat -O sample.stat -n 32768 -S k7-retired-instructions"
.Pp
To execute
.Nm mozilla
and measure the number of data cache misses suffered
by it and its children every 12 seconds on an AMD Athlon, use:
.Dl "pmcstat -d -w 12 -p k7-dc-misses mozilla"
.Pp
To collect a system-wide samples driven by processor instructions executed
use:
.Dl "pmcstat -S instructions -O /tmp/sample.out"
.Pp
To generate
.Xr gprof 1
compatible flat profiles from a sample file use:
.Dl "pmcstat -R /tmp/sample.out -g"
.Sh DIAGNOSTICS
.Ex -std
.Sh SEE ALSO
.Xr gprof 1 ,
.Xr execvp 3 ,
.Xr pmc 3 ,
.Xr pmclog 3 ,
.Xr hwpmc 4 ,
.Xr pmccontrol 8 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
utility first appeared in
.Fx 6.0 .
It is
.Ud
.Sh AUTHORS
.An Joseph Koshy Aq jkoshy@FreeBSD.org
.Sh BUGS
On AMD64 platforms
.Nm
does not yet handle profiles with samples from 32 bit executables.