cpupower-monitor - Report processor frequency and idle statistics
] [-i seconds
reports processor topology, frequency and idle power
state statistics. Either command
is forked and statistics are printed
upon its completion, or statistics are printed periodically.
implements independent processor sleep state and
frequency counters. Some are retrieved from kernel statistics, some are
directly reading out hardware registers. Use -l to get an overview which are
supported on your system.
List available monitors on your system.
Additional details about each monitor are shown:
- The name in quotation marks which can be passed to the -m
- The number of different counters the monitor supports in
- The amount of time in seconds the counters might overflow,
due to implementation constraints.
- The name and a description of each counter and its
processor hierarchy level coverage in square brackets:
- [T] -> Thread
- [C] -> Core
- [P] -> Processor Package (Socket)
- [M] -> Machine/Platform wide counter
Only display specific monitors. Use the
monitor string(s) provided by -l option.
Schedule the process on every core before
starting and ending measuring. This could be needed for the Idle_Stats monitor
when no other MSR based monitor (has to be run on the core that is measured)
is run in parallel. This is to wake up the processors from deeper sleep states
and let the kernel re -account its cpuidle (C-state) information before
reading the cpuidle timings from sysfs.
Measure idle and frequency characteristics of
an arbitrary command/workload. The executable command is forked and
upon its exit, statistics gathered since it was forked are displayed.
Increase verbosity if the binary was compiled
with the DEBUG option set.
Shows statistics of the cpuidle kernel subsystem. Values are retrieved from
/sys/devices/system/cpu/cpu*/cpuidle/state*/. The kernel updates these values
every time an idle state is entered or left. Therefore there can be some
inaccuracy when cores are in an idle state for some time when the measure
starts or ends. In worst case it can happen that one core stayed in an idle
state for the whole measure time and the idle state usage time as exported by
the kernel did not get updated. In this case a state residency of 0 percent is
shown while it was 100.
The name comes from the aperf/mperf (average and maximum) MSR registers used
which are available on recent X86 processors. It shows the average frequency
(including boost frequencies). The fact that on all recent hardware the mperf
timer stops ticking in any idle state it is also used to show C0 (processor is
active) and Cx (processor is in any sleep state) times. These counters do not
have the inaccuracy restrictions the "Idle_Stats" counters may show.
May work poorly on Linux-2.6.20 through 2.6.29, as the acpi-cpufreq
kernel frequency driver periodically cleared aperf/mperf registers in those
Intel Core and Package sleep state counters. Threads (hyperthreaded cores) may
not be able to enter deeper core states if its sibling is utilized. Deepest
package sleep states may in reality show up as machine/platform wide sleep
states and can only be entered if all cores are idle. Look up Intel manuals
(some are provided in the References section) for further details. The
monitors are named after the CPU family where the sleep state capabilities got
introduced and may not match exactly the CPU name of the platform. For example
an IvyBridge processor has sleep state capabilities which got introduced in
Nehalem and SandyBridge processor families. Thus on an IvyBridge processor one
will get Nehalem and SandyBridge sleep state monitors. HaswellExtended extra
package sleep state capabilities are available only in a specific Haswell
(family 0x45) and probably also other future processors.
AMD laptop and desktop processor (family 12h and 14h) sleep state counters. The
registers are accessed via PCI and therefore can still be read out while cores
have been offlined.
There is one special counter: NBP1 (North Bridge P1). This one always returns 0
or 1, depending on whether the North Bridge P1 power state got entered at
least once during measure time. Being able to enter NBP1 state also depends on
graphics power management. Therefore this counter can be used to verify
whether the graphics' driver power management is working as expected.
cpupower monitor -l" may show:
Monitor "Mperf" (3 states) - Might
overflow after 922000000 s
Monitor "Idle_Stats" (3 states) - Might overflow after 4294967295 s
cpupower monitor -m "Idle_Stats,Mperf" scp /tmp/test /nfs/tmp
Monitor the scp command, show both Mperf and Idle_Stats states counter
statistics, but in exchanged order.
Be careful that the typical command to fully utilize one CPU by doing:
cpupower monitor cat /dev/zero >/dev/null
Does not work as expected, because the measured output is redirected to
/dev/null. This could get workarounded by putting the line into an own, tiny
shell script. Hit CTRL-c to terminate the command and get the measure output
"BIOS and Kernel Developer’s Guide (BKDG) for AMD Family 14h
"Intel® Turbo Boost Technology in Intel® Core™
Microarchitecture (Nehalem) Based Processors"
"Intel® 64 and IA-32 Architectures Software Developer's Manual
Volume 3B: System Programming Guide"
powertop(8), msr(4), vmstat(8)
Written by Thomas Renninger <firstname.lastname@example.org>
Nehalem, SandyBridge monitors and command passing
based on turbostat.8 from Len Brown <email@example.com>