illumos: manual page: cputrack.1

CPUTRACK(1) User Commands CPUTRACK(1)

NAME

cputrack - monitor process and LWP behavior using CPU performance
counters

SYNOPSIS

cputrack -c eventspec [-c eventspec]... [-efntvD]
[-N count] [-o pathname] [-T interval] command [args]

cputrack -c eventspec [-c eventspec]... -p pid [-efntvD]
[-N count] [-o pathname] [-T interval]

cputrack -h

DESCRIPTION

The cputrack utility allows CPU performance counters to be used to
monitor the behavior of a process or family of processes running on the
system. If interval is specified with the -T option, cputrack samples
activity every interval seconds, repeating forever. If a count is
specified with the -N option, the statistics are repeated count times for
each process tracked. If neither are specified, an interval of one second
is used. If command and optional args are specified, cputrack runs the
command with the arguments given while monitoring the specified CPU
performance events. Alternatively, the process ID of an existing process
can be specified using the -p option.

Because cputrack is an unprivileged program, it is subject to the same
restrictions that apply to truss(1). For example, setuid(2) executables
cannot be tracked.

OPTIONS

The following options are supported:

-c eventspec
Specifies a set of events for the CPU performance
counters to monitor. The syntax of these event
specifications is:

[picn=]eventn[,attr[n][=val]][,[picn=]eventn
[,attr[n][=val]],...,]

You can use the -h option to obtain a list of available
events and attributes. This causes generation of the
usage message. You can omit an explicit counter
assignment, in which case cpustat attempts to choose a
capable counter automatically.

Attribute values can be expressed in hexadecimal, octal,
or decimal notation, in a format suitable for
strtoll(3C). An attribute present in the event
specification without an explicit value receives a
default value of 1. An attribute without a corresponding
counter number is applied to all counters in the
specification.

The semantics of these event specifications can be
determined by reading the CPU manufacturer's
documentation for the events.

Multiple -c options can be specified, in which case
cputrack cycles between the different event settings on
each sample.

-D
Enables debug mode.

-e
Follows all exec(2), or execve(2) system calls.

-f
Follows all children created by fork(2), fork1(2), or
vfork(2) system calls.

-h
Prints an extended help message on how to use the
utility, how to program the processor-dependent counters,
and where to look for more detailed information.

-n
Omits all header output (useful if cputrack is the
beginning of a pipeline).

-N count
Specifies the maximum number of CPU performance counter
samples to take before exiting.

-o outfile
Specifies file to be used for the cputrack output.

-p pid
Interprets the argument as the process ID of an existing
process to which process counter context should be
attached and monitored.

-t
Prints an additional column of processor cycle counts, if
available on the current architecture.

-T interval
Specifies the interval between CPU performance counter
samples in seconds. Very small intervals may cause some
samples to be skipped. See WARNINGS.

-v
Enables more verbose output.

USAGE

The operating system enforces certain restrictions on the tracing of
processes. In particular, a command whose object file cannot be read by
a user cannot be tracked by that user; set-uid and set-gid commands can
only be tracked by a privileged user. Unless it is run by a privileged
user, cputrack loses control of any process that performs an exec() of a
set-id or unreadable object file. Such processes continue normally,
though independently of cputrack, from the point of the exec().

The system may run out of per-user process slots when the -f option is
used, since cputrack runs one controlling process for each process being
tracked.

The times printed by cputrack correspond to the wallclock time when the
hardware counters were actually sample. The time is derived from the same
timebase as gethrtime(3C).

The cputrack utility attaches performance counter context to each process
that it examines. The presence of this context allows the performance
counters to be multiplexed between different processes on the system, but
it cannot be used at the same time as the cpustat(8) utility.

Once an instance of the cpustat utility is running, further attempts to
run cputrack will fail until all instances of cpustat terminate.

Sometimes cputrack provides sufficient flexibility and prints sufficient
statistics to make adding the observation code to an application
unnecessary. However, more control is occasionally desired. Because the
same performance counter context is used by both the application itself
and by the agent LWP injected into the application by cputrack, it is
possible for an application to interact with the counter context to
achieve some interesting capabilities. See cpc_enable(3CPC).

The processor cycle counts enabled by the -t option always apply to both
user and system modes, regardless of the settings applied to the
performance counter registers.

The output of cputrack is designed to be readily parsable by nawk(1) and
perl(1), thereby allowing performance tools to be composed by embedding
cputrack in scripts. Alternatively, tools may be constructed directly
using the same APIs that cputrack is built upon, using the facilities of
libcpc(3LIB) and libpctx(3LIB). See cpc(3CPC).

Although cputrack uses performance counter context to maintain separate
performance counter values for each LWP, some of the events that can be
counted will inevitably be impacted by other activities occurring on the
system, particularly for limited resources that are shared between
processes (for example, cache miss rates). For such events, it may also
be interesting to observe overall system behavior with cpustat(8).

For the -T interval option, if interval is specified as zero, no periodic
sampling is performed. The performance counters are only sampled when the
process creates or destroys an LWP, or it invokes fork(2), exec(2), or
exit(2).

EXAMPLES

SPARC

Example 1: Using Performance Counters to Count Clock Cycles

In this example, the utility is being used on a machine containing an
UltraSPARC-III+ processor. The counters are set to count processor clock
cycles and instructions dispatched in user mode while running the
sleep(1) command.

example% cputrack -c pic0=Cycle_cnt,pic1=Instr_cnt sleep 10

time lwp event pic0 pic1
1.007 1 tick 765308 219233
2.007 1 tick 0 0
4.017 1 tick 0 0
6.007 1 tick 0 0
8.007 1 tick 0 0
10.007 1 tick 0 0
10.017 1 exit 844703 228058

Example 2: Counting External Cache References and Misses

This example shows more verbose output while following the fork() and
exec() of a simple shell script on an UltraSPARC machine. The counters
are measuring the number of external cache references and external cache
misses. Notice that the explicit pic0 and pic1 names can be omitted where
there are no ambiguities.

example% cputrack -fev -c EC_ref,EC_hit /bin/ulimit -c

time pid lwp event pic0 pic1
0.007 101142 1 init_lwp 805286 20023
0.023 101142 1 fork # 101143
0.026 101143 1 init_lwp 1015382 24461
0.029 101143 1 fini_lwp 1025546 25074
0.029 101143 1 exec 1025546 25074
0.000 101143 1 exec \
# '/usr/bin/sh /usr/bin/basename \
/bin/ulimit'
0.039 101143 1 init_lwp 1025546 25074
0.050 101143 1 fini_lwp 1140482 27806
0.050 101143 1 exec 1140482 27806
0.000 101143 1 exec # '/usr/bin/expr \
//bin/ulimit : $.*[^/]$/*$ : .*/ $..*$ : $.*$$ | //bin/ulimi'
0.059 101143 1 init_lwp 1140482 27806
0.075 101143 1 fini_lwp 1237647 30207
0.075 101143 1 exit 1237647 30207
unlimited
0.081 101142 1 fini_lwp 953383 23814
0.081 101142 1 exit 953383 23814

x86

Example 3: Counting Instructions

This example shows how many instructions were executed in the application
and in the kernel to print the date on a Pentium III machine:

example% cputrack -c inst_retired,inst_retired,nouser1,sys1 date

time lwp event pic0 pic1
Fri Aug 20 20:03:08 PDT 1999
0.072 1 exit 246725 339666

Example 4: Counting TLB Hits

This example shows how to use processor-specific attributes to count TLB
hits on a Pentium 4 machine:

example% cputrack -c ITLB_reference,emask=1 date

time lwp event pic0
Fri Aug 20 20:03:08 PDT 1999
0.072 1 exit 246725

WARNINGS

By running any instance of the cpustat(8) utility, all existing
performance counter context is forcibly invalidated across the machine.
This may in turn cause all invocations of the cputrack command to exit
prematurely with unspecified errors.

If cpustat is invoked on a system that has CPU performance counters which
are not supported by Solaris, the following message appears:

cputrack: cannot access performance counters - Operation not applicable

This error message implies that cpc_open() has failed and is documented
in cpc_open(3CPC). Review this documentation for more information about
the problem and possible solutions.

If a short interval is requested, cputrack may not be able to keep up
with the desired sample rate. In this case, some samples may be dropped.

ATTRIBUTES