[PATCH 0/1] cpupower: monitor: Show how a counter value is exported

[Hemanth Selam]

Hi,

this picks up the ToDo in list_monitors() which asks to show more of the
capabilities of a counter.

"cpupower monitor -l" tells the name of a counter, the processor
hierarchy level it covers and its description, but it does not tell how
the value of the counter is exported. That is not obvious from the
description either: most counters are a percentage of the time spent in
a state, while for example the Mperf "Freq" counter reports MHz and the
RAPL zones report micro Joule. Without that information the numbers of
a measurement run are hard to interpret.

The value type is now printed behind the hierarchy level, using the
square bracket notation the hierarchy level already uses:

  [%]   The counter is a percentage of the time spent in the state.
  [abs] The counter is an absolute value, its unit depends on the
        counter, MHz for "Freq" or micro Joule for a RAPL zone.

The man page is updated in the same patch, right below the description
of the [T], [C], [P] and [M] hierarchy levels.

Note that "%" and "abs" are deliberately not single letters: [C] and
[P] are already taken by the Core and Package hierarchy levels, so
reusing them would render counters as "[P] [C]" or "[C] [P]", which
cannot be read unambiguously.

The second half of the ToDo, showing the time granularity of a counter,
is not implemented. There is no per state granularity information
today, only the per monitor overflow time which is already printed. It
would need a new cstate_t member every monitor has to fill in, so the
ToDo is kept, narrowed down to what is left to do.

Tested with the Mperf and Idle_Stats monitors:

  $ cpupower monitor -l
  Monitor "Mperf" (3 states) - Might overflow after 922000000 s
  C0	[T] [%] -> Processor Core not idle
  Cx	[T] [%] -> Processor Core in an idle state
  Freq	[T] [abs] -> Average Frequency (including boost) in MHz
  Monitor "Idle_Stats" (3 states) - Might overflow after 4294967295 s
  POLL	[T] [%] -> CPUIDLE CORE POLL IDLE
  C1	[T] [%] -> ACPI FFH MWAIT 0x0
  C2	[T] [%] -> ACPI IOPORT 0x814

Measurement runs, "cpupower monitor -i 1" and "cpupower monitor -m
Mperf -i 1", print the same output as before, only the listing changed.

Thanks,
Hemanth

Hemanth Selam (1):
  cpupower: monitor: Show how a counter value is exported

 tools/power/cpupower/man/cpupower-monitor.1   |  8 +++++++
 .../utils/idle_monitor/cpupower-monitor.c     | 22 ++++++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

-- 
2.43.7