Xeon E5 cpu work in low status

[Adrian Chadd]

.. and what I'd really like to see is some tools to inspect power
consumption on the CPU side of things.

I'd also like something for the GPU side of things too. I can't find
anything in our DRM driver code that twiddles the clock PLL registers
to slow things down.

Thanks,



-adrian

On 4 November 2013 10:00, Adrian Chadd <adrian at freebsd.org> wrote:
> A lot of us think this. The question is .. who's going to fix it?
>
> :-)
>
>
>
> -adrian
>
>
> On 4 November 2013 09:52, Kevin Oberman <rkoberman at gmail.com> wrote:
>> On Mon, Nov 4, 2013 at 12:46 AM, 李森 <lisen1001 at gmail.com> wrote:
>>
>>> hi,all:
>>>         the cpu of my machine is :  Intel(R) Xeon(R) CPU E5-2643 0 @
>>> 3.30GHz.
>>>
>>>         after a reboot. The cpu freq is : sysctl dev.cpu.0.freq
>>> dev.cpu.0.freq: 1200
>>>
>>>         i didn't set any power savings config in rc.conf.
>>>
>>>         How can i fix this?
>>>
>>
>> It's not clear what is broken. Is the server busy? Is there some reason to
>> expect it to be running at full clock-rate?
>>
>> What is the content of dev.cpu.0.freq_levels?
>>
>> By default, FreeBSD runs powerd and that will, by default, throttle back
>> the clock when the system is not busy. I think that this is a bad thing.,
>> but it is not a bug. It's by design. I really think, based on my own
>> testing, research and a major NSF computer center (SDSC), and work done by
>> mav@ which can be found on the FreeBSD wiki (
>> https://wiki.freebsd.org/TuningPowerConsumption), those "power management"
>> tools are broken by design a they are actually there for thermal control,
>> not power management and are, at best, break-even, and in most cases are
>> actually a loser in both power savings and system performance. (There are a
>> very few edge cases where they can be beneficial, but as a side effect for
>> very specific loads under fairly unusual circumstances.)
>>
>> To turn off these (mis)features, add the following to /boot/loader.conf:
>> # Disable CPU throttling
>> hint.p4tcc.0.disabled=1
>> hint.acpi_throttle.0.disabled=1
>>
>> <rant>
>> All real power management is through the use of EST and CPU sleep (CX)
>> states. These  can provide a big power win at minimal performance impact.
>> Unfortunately CX states and throttling lay very badly together, probably
>> because processor designers don't think that TCC and throttling are for
>> power management, so are not an issue.
>>
>> For reasons that have always baffled me, rather than disable the
>> inappropriate use of thermal management as power management, we disable the
>> most effective power management tools by default.
>> performance_cx_lowest="HIGH" # Online CPU idle state
>> economy_cx_lowest="HIGH" # Offline CPU idle state
>>
>> Even the comments are confusing: what do "Online" and "Offline" mean?
>> Offline means running on battery and online means AC power.
>>
>> In any case, it's not clear that there is any issue with your system other
>> than that, by default, FreeBSD tries to really, really hard to manage power
>> as badly as humanly possible.
>> </rant>
>>
>> --
>> R. Kevin Oberman, Network Engineer
>> E-mail: rkoberman at gmail.com
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