CPU C-state storange on Panasonic TOUGH BOOK CF-R9

Alexander Motin mav at FreeBSD.org
Sun Sep 12 08:12:44 UTC 2010

Andriy Gapon wrote:
> on 11/09/2010 21:30 Nate Lawson said the following:
>>> PROCESSOR-0311 [255895] cpu_attach            : acpi_cpu3: P_BLK at 0x410/6
>>> PROCESSOR-0696 [257314] cpu_cx_cst            : acpi_cpu3: C2[1] not available.
>>> PROCESSOR-0730 [257314] cpu_cx_cst            : acpi_cpu3: Got C3 - 245 latency
>> I think the issue is that C2 is not available for some reason and thus
>> C3 can't be used either. The way to tell is to use acpidump and look for
>> the CPU objects' _CST fields.
> The "not available" message means that transition latency is defined too high.
> That is, in this case latency is greater than 100 for C2.

Just an idea. Limits of 100 and 1000 are defined for detection of
C-states using P_LVLx_LAT registers. Because _CST explicitly specifies
which states are available, these limitations may not apply there. I
would try to comment these checks in acpi_cpu_cx_cst() and look what
happen. At least I haven't found in ACPI 3.0 specification any latency
limits applied to _CST.

Alexander Motin

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