Xeon E5 cpu work in low status

[Adrian Chadd]

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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