On Thu, Apr 10, 2014 at 12:18 AM, Kevin Oberman <rkober...@gmail.com> wrote:
> On Wed, Apr 9, 2014 at 11:22 AM, hiren panchasara
> <hiren.panchas...@gmail.com> wrote:
>>
>> On Wed, Apr 9, 2014 at 11:07 AM, Anton Sayetsky <vsj...@gmail.com> wrote:
>> > 2014-04-09 20:40 GMT+03:00 hiren panchasara
>> > <hiren.panchas...@gmail.com>:
>> >> I am running -current on my T420 at r263906M
>> >>
>> >> debug.acpi.acpi_ca_version: 20130823
>> >>
>> >> o/p of sysctl -a | grep acpi - http://bpaste.net/show/199806/
>> >>
>> >>  and I have following in my rc.conf:
>> >>
>> >> performance_cx_lowest="Cmax"
>> >> economy_cx_lowest="Cmax"
>> >>
>> >> But I still get:
>> >>
>> >> % sysctl -a | grep cx_lowest
>> >> hw.acpi.cpu.cx_lowest: C1
>> >> dev.cpu.0.cx_lowest: C1
>> >> dev.cpu.1.cx_lowest: C1
>> >> dev.cpu.2.cx_lowest: C1
>> >> dev.cpu.3.cx_lowest: C1
>> >>
>> >> And I can do:
>> >> # sysctl dev.cpu.0.cx_lowest=Cmax
>> >> dev.cpu.0.cx_lowest: C1 -> C8
>> >>
>> >> that tells me that Cmax is C8.
>> >>
>> >> % sysctl -d dev.cpu.0.cx_lowest
>> >> dev.cpu.0.cx_lowest: lowest Cx sleep state to use
>> >>
>> >> I was expecting cx_lowest to be set to C8 because of rc.conf config I
>> >> have.
>> >>
>> >> What am I missing here?
>> >>
>> >> cheers,
>> >> Hiren
>> > Try to set LOW instead of Cmax.
>>
>> I will try it again.
>>
>> Interestingly enough, on an amd machine, it worked as I expected with
>> a bit more current version of -head but same version of acpica:
>> debug.acpi.acpi_ca_version: 20130823
>>
>> cpus came up with cx_lowest set to C8 with Cmax in rc.conf
>>
>> cheers,
>> Hiren
>
>
> Setting Cx values is a bit confusing.  Things may not mean what you think.
> CMax is always C8 because this is the largest possible value of a Cx state,
> not because C8 is actually available.The reason for this is that some
> systems have non-sequencial Cx states. That is the maximum value my be C5,
> but C2 may not be available. So the idea is to allow ANY C-state up to the
> maximum. LOWEST works well as long as no states are skipped. If they are,
> you are limited to the states before the skipped state.
>
> To see the actual available states, look at dev.cpu.0.cx_supported.
>
> The recommended value for best power savings is :Cmax. That will allow
> skipping over missing C-states. Also, the available states often differ
> between AC power and battery. On my T320:
> AC         dev.cpu.0.cx_supported: C1/1/1 C2/3/104
> Battery  dev.cpu.0.cx_supported: C1/1/1 C2/2/80 C3/3/109

AC:
hw.acpi.cpu.cx_lowest: C8
dev.cpu.0.cx_supported: C1/1/1 C2/3/104
dev.cpu.0.cx_lowest: C8
dev.cpu.0.cx_usage: 8.23% 91.76% last 38us

Battery:
hw.acpi.cpu.cx_lowest: C8
dev.cpu.0.cx_supported: C1/1/1 C2/2/80 C3/3/109
dev.cpu.0.cx_lowest: C8
dev.cpu.0.cx_usage: 12.35% 3.22% 84.42% last 3088us

So, pretty similar on my T420 with following in rc.conf
performance_cx_lowest="Cmax"
economy_cx_lowest="Cmax"

How do I know what C-state cpu0 is in, at any point in time? Or thats
not how things work?

cheers,
Hiren
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