Hi John,

Thanks for the validation!
This is what I expected. Your system has deep c-state supported now, :)
Yeah, powertop doesn't work because we can't use dtrace and kmdb together.
But you still can observe c-state info by kstat.

$ kstat | grep current_cstate

You should see C0, C1, and C3 there.

Thanks,
-Aubrey


John.M.Martin <> wrote:

> Li, Aubrey wrote:
>> 
>> It looks like the BIOS only support native deep cstate method.
>> We probably need to enable PDC.bit9.
>> 
>> John, could you please help to verify it on your system?
>> 
>> 1) reboot the system and enter kmdb
>> 
>> 2) set a breakpoint at cpu_acpi_write_pdc()
>> [0]> cpu_acpi_write_pdc:b
>> 
>> 3) continue to hit the breakpoint
>> [0]> :c
>> 
>> 4) when the breakpoint is hit, change "cpupm_intel_pdccap" to 0xBBF.
>> [0]> cpupm_intel_pdccap/W 0xBBF
>> 
>> 5) continue to boot the system.
>> 
> FWIW, on each of the eight i7 920 "cpus", 0xbbf replaced 0x9bf.
> 
> This experiment was more complex than anticipated.  The first
> breakpoint went fine.  On the second breakpoint ([1]> ) no input was
> accepted 
> on the USB console keyboard.  Switching this keyboard to the PS/2
> input with a dongle fixed the problem.
> 
> After the system booted, powertop fails with:
> 
>   powertop: ../common/cpufreq.c : cannot open dtrace library: DTrace
> cannot be used when kernel debugger is active
> 
> but "kstat cstate" now produces output (it didn't before).  If it
> matters, the SBIOS option is still set to "Auto".
> 
> # kstat cstate
> module: cstate                          instance: 1
> name:   c1                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          201.053737219
>     latency                         1
>     power                           1000
>     snaptime                        618.987573382
> 
> module: cstate                          instance: 1
> name:   c3                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          201.053738694
>     latency                         96
>     power                           350
>     snaptime                        618.987763894
> 
> module: cstate                          instance: 2
> name:   c1                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          235.491583585
>     latency                         1
>     power                           1000
>     snaptime                        618.987868627
> 
> module: cstate                          instance: 2
> name:   c3                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          235.491585306
>     latency                         96
>     power                           350
>     snaptime                        618.987962843
> 
> module: cstate                          instance: 3
> name:   c1                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          254.080557069
>     latency                         1
>     power                           1000
>     snaptime                        618.988062766
> 
> module: cstate                          instance: 3
> name:   c3                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          254.080558851
>     latency                         96
>     power                           350
>     snaptime                        618.988155771
> 
> module: cstate                          instance: 4
> name:   c1                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          301.460281258
>     latency                         1
>     power                           1000
>     snaptime                        618.98825552
> 
> module: cstate                          instance: 4
> name:   c3                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          301.460282866
>     latency                         96
>     power                           350
>     snaptime                        618.988349078
> 
> module: cstate                          instance: 5
> name:   c1                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          354.306818526
>     latency                         1
>     power                           1000
>     snaptime                        618.988449423
> 
> module: cstate                          instance: 5
> name:   c3                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          354.306820203
>     latency                         96
>     power                           350
>     snaptime                        618.988542142
> 
> module: cstate                          instance: 6
> name:   c1                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          373.751687887
>     latency                         1
>     power                           1000
>     snaptime                        618.988660284
> 
> module: cstate                          instance: 6
> name:   c3                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          373.751690036
>     latency                         96
>     power                           350
>     snaptime                        618.988753932
> 
> module: cstate                          instance: 7
> name:   c1                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          388.831011112
>     latency                         1
>     power                           1000
>     snaptime                        618.988854217
> 
> module: cstate                          instance: 7
> name:   c3                              class:    misc
>     address_space_id                FFixedHW
>     crtime                          388.831013099
>     latency                         96
>     power                           350
>     snaptime                        618.988947075
> 
> #

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