191 lines
5.9 KiB
Groff
191 lines
5.9 KiB
Groff
.TH CPUPOWER\-MONITOR "1" "22/02/2011" "" "cpupower Manual"
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.SH NAME
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cpupower\-monitor \- Report processor frequency and idle statistics
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.SH SYNOPSIS
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.ft B
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.B cpupower monitor
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.RB "\-l"
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.B cpupower monitor
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.RB [ -c ] [ "\-m <mon1>," [ "<mon2>,..." ] ]
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.RB [ "\-i seconds" ]
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.br
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.B cpupower monitor
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.RB [ -c ][ "\-m <mon1>," [ "<mon2>,..." ] ]
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.RB command
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.br
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.SH DESCRIPTION
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\fBcpupower-monitor \fP reports processor topology, frequency and idle power
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state statistics. Either \fBcommand\fP is forked and
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statistics are printed upon its completion, or statistics are printed periodically.
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\fBcpupower-monitor \fP implements independent processor sleep state and
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frequency counters. Some are retrieved from kernel statistics, some are
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directly reading out hardware registers. Use \-l to get an overview which are
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supported on your system.
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.SH Options
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.PP
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\-l
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.RS 4
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List available monitors on your system. Additional details about each monitor
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are shown:
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.RS 2
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.IP \(bu
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The name in quotation marks which can be passed to the \-m parameter.
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.IP \(bu
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The number of different counters the monitor supports in brackets.
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.IP \(bu
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The amount of time in seconds the counters might overflow, due to
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implementation constraints.
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.IP \(bu
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The name and a description of each counter and its processor hierarchy level
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coverage in square brackets:
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.RS 4
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.IP \(bu
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[T] \-> Thread
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.IP \(bu
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[C] \-> Core
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.IP \(bu
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[P] \-> Processor Package (Socket)
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.IP \(bu
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[M] \-> Machine/Platform wide counter
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.RE
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.RE
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.RE
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.PP
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\-m <mon1>,<mon2>,...
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.RS 4
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Only display specific monitors. Use the monitor string(s) provided by \-l option.
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.RE
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.PP
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\-i seconds
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.RS 4
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Measure intervall.
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.RE
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.PP
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\-c
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.RS 4
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Schedule the process on every core before starting and ending measuring.
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This could be needed for the Idle_Stats monitor when no other MSR based
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monitor (has to be run on the core that is measured) is run in parallel.
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This is to wake up the processors from deeper sleep states and let the
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kernel re
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-account its cpuidle (C-state) information before reading the
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cpuidle timings from sysfs.
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.RE
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.PP
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command
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.RS 4
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Measure idle and frequency characteristics of an arbitrary command/workload.
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The executable \fBcommand\fP is forked and upon its exit, statistics gathered since it was
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forked are displayed.
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.RE
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.PP
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\-v
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.RS 4
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Increase verbosity if the binary was compiled with the DEBUG option set.
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.RE
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.SH MONITOR DESCRIPTIONS
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.SS "Idle_Stats"
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Shows statistics of the cpuidle kernel subsystem. Values are retrieved from
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/sys/devices/system/cpu/cpu*/cpuidle/state*/.
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The kernel updates these values every time an idle state is entered or
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left. Therefore there can be some inaccuracy when cores are in an idle
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state for some time when the measure starts or ends. In worst case it can happen
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that one core stayed in an idle state for the whole measure time and the idle
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state usage time as exported by the kernel did not get updated. In this case
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a state residency of 0 percent is shown while it was 100.
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.SS "Mperf"
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The name comes from the aperf/mperf (average and maximum) MSR registers used
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which are available on recent X86 processors. It shows the average frequency
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(including boost frequencies).
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The fact that on all recent hardware the mperf timer stops ticking in any idle
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state it is also used to show C0 (processor is active) and Cx (processor is in
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any sleep state) times. These counters do not have the inaccuracy restrictions
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the "Idle_Stats" counters may show.
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May work poorly on Linux-2.6.20 through 2.6.29, as the \fBacpi-cpufreq \fP
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kernel frequency driver periodically cleared aperf/mperf registers in those
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kernels.
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.SS "Nehalem" "SandyBridge"
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Intel Core and Package sleep state counters.
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Threads (hyperthreaded cores) may not be able to enter deeper core states if
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its sibling is utilized.
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Deepest package sleep states may in reality show up as machine/platform wide
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sleep states and can only be entered if all cores are idle. Look up Intel
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manuals (some are provided in the References section) for further details.
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.SS "Fam_12h" "Fam_14h"
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AMD laptop and desktop processor (family 12h and 14h) sleep state counters.
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The registers are accessed via PCI and therefore can still be read out while
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cores have been offlined.
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There is one special counter: NBP1 (North Bridge P1).
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This one always returns 0 or 1, depending on whether the North Bridge P1
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power state got entered at least once during measure time.
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Being able to enter NBP1 state also depends on graphics power management.
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Therefore this counter can be used to verify whether the graphics' driver
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power management is working as expected.
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.SH EXAMPLES
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cpupower monitor -l" may show:
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.RS 4
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Monitor "Mperf" (3 states) \- Might overflow after 922000000 s
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...
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Monitor "Idle_Stats" (3 states) \- Might overflow after 4294967295 s
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...
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.RE
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cpupower monitor \-m "Idle_Stats,Mperf" scp /tmp/test /nfs/tmp
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Monitor the scp command, show both Mperf and Idle_Stats states counter
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statistics, but in exchanged order.
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.RE
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Be careful that the typical command to fully utilize one CPU by doing:
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cpupower monitor cat /dev/zero >/dev/null
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Does not work as expected, because the measured output is redirected to
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/dev/null. This could get workarounded by putting the line into an own, tiny
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shell script. Hit CTRL\-c to terminate the command and get the measure output
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displayed.
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.SH REFERENCES
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"BIOS and Kernel Developer’s Guide (BKDG) for AMD Family 14h Processors"
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http://support.amd.com/us/Processor_TechDocs/43170.pdf
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"Intel® Turbo Boost Technology
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in Intel® Core™ Microarchitecture (Nehalem) Based Processors"
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http://download.intel.com/design/processor/applnots/320354.pdf
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"Intel® 64 and IA-32 Architectures Software Developer's Manual
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Volume 3B: System Programming Guide"
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http://www.intel.com/products/processor/manuals
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.SH FILES
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.ta
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.nf
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/dev/cpu/*/msr
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/sys/devices/system/cpu/cpu*/cpuidle/state*/.
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.fi
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.SH "SEE ALSO"
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powertop(8), msr(4), vmstat(8)
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.PP
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.SH AUTHORS
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.nf
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Written by Thomas Renninger <trenn@suse.de>
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Nehalem, SandyBridge monitors and command passing
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based on turbostat.8 from Len Brown <len.brown@intel.com>
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