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Maintenance Commands CPUSTAT(1M)
NAME
cpustat - monitor system behavior using CPU performance
counters
SYNOPSIS
cpustat -c eventspec [-c eventspec]... [-p period] [-T u | d ]
[-sntD] [interval [count]]
cpustat -h
DESCRIPTION
The cpustat utility allows CPU performance counters to be
used to monitor the overall behavior of the CPUs in the sys-
tem.
If interval is specified, cpustat samples activity every
interval seconds, repeating forever. If a count is speci-
fied, the statistics are repeated count times. If neither
are specified, an interval of five seconds is used, and
there is no limit to the number of samples that are taken.
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 specifi-
cations 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 assign-
ment, 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 specifi-
cation 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
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documentation for the events.
Multiple -c options can be specified, in which case the
command cycles between the different event settings on
each sample.
-D
Enables debug mode.
-h
Prints an extensive help message on how to use the util-
ity and how to program the processor-dependent counters.
-n
Omits all header output (useful if cpustat is the begin-
ning of a pipeline).
-p period
Causes cpustat to cycle through the list of eventspecs
every period seconds. The tool sleeps after each cycle
until period seconds have elapsed since the first
eventspec was measured.
When this option is present, the optional count parame-
ter specifies the number of total cycles to make
(instead of the number of total samples to take). If
period is less than the number of eventspecs times
interval, the tool acts as it period is 0.
-s
Creates an idle soaker thread to spin while system-only
eventspecs are bound. One idle soaker thread is bound to
each CPU in the current processor set. System-only
eventspecs contain both the nouser and the sys tokens
and measure events that occur while the CPU is operating
in privileged mode. This option prevents the kernel's
idle loop from running and triggering system-mode
events.
-T u | d
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Display a time stamp.
Specify u for a printed representation of the internal
representation of time. See time(2). Specify d for stan-
dard date format. See date(1).
-t
Prints an additional column of processor cycle counts,
if available on the current architecture.
USAGE
A closely related utility, cputrack(1), can be used to moni-
tor the behavior of individual applications with little or
no interference from other activities on the system.
The cpustat utility must be run by the super-user, as there
is an intrinsic conflict between the use of the CPU perfor-
mance counters system-wide by cpustat and the use of the CPU
performance counters to monitor an individual process (for
example, by cputrack.)
Once any instance of this utility has started, no further
per-process or per-LWP use of the counters is allowed until
the last instance of the utility terminates.
The times printed by the command 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 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.
On some hardware platforms running in system mode using the
"sys" token, the counters are implemented using 32-bit
registers. While the kernel attempts to catch all overflows
to synthesize 64-bit counters, because of hardware implemen-
tation restrictions, overflows can be lost unless the sam-
pling interval is kept short enough. The events most prone
to wrap are those that count processor clock cycles. If such
an event is of interest, sampling should occur frequently so
that less than 4 billion clock cycles can occur between sam-
ples.
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The output of cpustat is designed to be readily parseable by
nawk(1) and perl(1), thereby allowing performance tools to
be composed by embedding cpustat in scripts. Alternatively,
tools can be constructed directly using the same APIs that
cpustat is built upon using the facilities of libcpc(3LIB).
See cpc(3CPC).
The cpustat utility only monitors the CPUs that are accessi-
ble to it in the current processor set. Thus, several
instances of the utility can be running on the CPUs in dif-
ferent processor sets. See psrset(1M) for more information
about processor sets.
Because cpustat uses LWPs bound to CPUs, the utility might
have to be terminated before the configuration of the
relevant processor can be changed.
EXAMPLES
SPARC
Example 1 Measuring External Cache References and Misses
The following example measures misses and references in the
external cache. These occur while the processor is operat-
ing in user mode on an UltraSPARC machine.
example% cpustat -c EC_ref,EC_misses 1 3
time cpu event pic0 pic1
1.008 0 tick 69284 1647
1.008 1 tick 43284 1175
2.008 0 tick 179576 1834
2.008 1 tick 202022 12046
3.008 0 tick 93262 384
3.008 1 tick 63649 1118
3.008 2 total 651077 18204
x86
Example 2 Measuring Branch Prediction Success on Pentium 4
The following example measures branch mispredictions and
total branch instructions in user and system mode on a Pen-
tium 4 machine.
example% cpustat -c \
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pic12=branch_retired,emask12=0x4,pic14=branch_retired,\
emask14=0xf,sys 1 3
time cpu event pic12 pic14
1.010 1 tick 458 684
1.010 0 tick 305 511
2.010 0 tick 181 269
2.010 1 tick 469 684
3.010 0 tick 182 269
3.010 1 tick 468 684
3.010 2 total 2063 3101
Example 3 Counting Memory Accesses on Opteron
The following example determines the number of memory
accesses made through each memory controller on an Opteron,
broken down by internal memory latency:
cpustat -c \
pic0=NB_mem_ctrlr_page_access,umask0=0x01, \
pic1=NB_mem_ctrlr_page_access,umask1=0x02, \
pic2=NB_mem_ctrlr_page_access,umask2=0x04,sys \
1
time cpu event pic0 pic1 pic2
1.003 0 tick 41976 53519 7720
1.003 1 tick 5589 19402 731
2.003 1 tick 6011 17005 658
2.003 0 tick 43944 45473 7338
3.003 1 tick 7105 20177 762
3.003 0 tick 47045 48025 7119
4.003 0 tick 43224 46296 6694
4.003 1 tick 5366 19114 652
WARNINGS
By running the cpustat command, the super-user forcibly
invalidates all existing performance counter context. This
can in turn cause all invocations of the cputrack command,
and other users of performance counter context, 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:
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cpustat: 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, cpustat might not be able
to keep up with the desired sample rate. In this case, some
samples might be dropped.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
_______________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE|
|____________________|_________________|
| Interface Stability| Evolving |
|____________________|_________________|
SEE ALSO
cputrack(1), nawk(1), perl(1), iostat(1M), prstat(1M),
psrset(1M), vmstat(1M), cpc(3CPC), cpc_open(3CPC),
cpc_bind_cpu(3CPC), gethrtime(3C), strtoll(3C),
libcpc(3LIB), attributes(5)
NOTES
When cpustat is run on a Pentium 4 with HyperThreading
enabled, a CPC set is bound to only one logical CPU of each
physical CPU. See cpc_bind_cpu(3CPC).
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