cputrack(1)
NAME
cputrack - monitor process and LWP behavior using CPU per-
formance 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 speci-
fied, 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 exam-
ple, 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 list of available events and
the syntax of the event specifications for the system
can be determined using the -h option. The semantics
of these event specifications can be determined by
reading the CPU manufacturers documentation for the
events. See cpc_strtoevent(3CPC) for a description of
the syntax.
Multiple -c options may 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.
Without this option, cputrack terminates when the
process image is overlaid with a new executable.
-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 and how to program the processor-dependent
counters.
-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 exist-
ing 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, cpu-
track loses control of any process that performs an exec()
of a set-id or unreadable object file. Such processes con-
tinue 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 sampled,
instead of when the program told the kernel to sample them.
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(1M) 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 event selec-
tion code to an application unnecessary. However, more con-
trol 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_count_usr_events(3CPC).
The processor cycle counts enabled by the -t option always
apply to both user and system modes, regardless of the set-
tings applied to the performance counter registers.
The output of cputrack is designed to be readily parseable
by nawk(1) and perl(1), thereby allowing performance tools
to be composed by embedding cputrack in scripts. Alterna-
tively, 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 main-
tain 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, par-
ticularly 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(1M).
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 des-
troys 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 con-
taining an UltraSPARC 1 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
2.040 1 tick 377820 202593
4.028 1 tick 0 0
6.028 1 tick 0 0
8.028 1 tick 0 0
10.028 1 tick 6930 954
10.036 1 exit 410623 212137
Example 2: Counting external cache references and hits
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 hits. 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
0.032 101200 1 init_lwp 0 0
0.106 101200 1 fork # 101201
0.115 101201 1 init_lwp 0 0
0.179 101201 1 fini_lwp 5934 5031
0.179 101201 1 exec 5934 5031
0.399 101201 1 exec # 'basename /bin/ulimit'
0.413 101201 1 init_lwp 0 0
0.435 101201 1 fini_lwp 19780 17234
0.435 101201 1 exit 19780 17234 unlimited
0.454 101200 1 fini_lwp 63025 54583
0.454 101200 1 exit 63025 54583
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 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
WARNINGS
By running any instance of the cpustat(1M) 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 cputrack is invoked on a system that has CPU performance
counters, but on which the packages containing the kernel
support for those counters is not installed, the following
message appears:
cputrack: CPU performance counters are inaccessible on this machine
This error message implies that cpc_access() has failed and
is documented in cpc_access(3CPC). Review this documentation
for more information about the problem and possible solu-
tions.
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
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWcpcu (32-bit) |
|_____________________________|_____________________________|
| | SUNWcpcux (64-bit) |
|_____________________________|_____________________________|
| Interface Stability | Evolving |
|_____________________________|_____________________________|
SEE ALSO
nawk(1), perl(1), proc(1), truss(1), prstat(1M),
cpustat(1M), exec(2), exit(2), fork(2), setuid(2), vfork(2),
gethrtime(3C), cpc(3CPC), cpc_access(3CPC),
cpc_count_usr_events(3CPC), cpc_strtoevent(3CPC),
libcpc(3LIB), libpctx(3LIB), proc(4), attributes(5)
Sun Microsystems UltraSPARC IIi and III Cu (v.2.2.1) User's
Manuals, 1997 and 2004,
respectivelyhttp://www.sun.com/processors
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