Re: Power-Mgt (Was: Re: cvs commit: src/sys/i386/cpufreq est.c )

In message <20080318185435.GA2853@xxxxxxxxxxxxxxxxxxxxxx>, Brooks Davis writes:

For amusement value, I had a dual P4-Xeon box hooked up to one once
and found that power consumption with SETI@Home running was about 10W
_lower_ than idle.

That is a very good indication that the meter is a piece of crap that
does not have sufficient measurement rate to do a relevant job.

Unfortunately, that is the case for most of the gadgets you can buy
in shops.

In general, you are much better off buying the real thing, for instance
a single-phase DIN power-meter like:

http://www.metermaid.co.uk/din_rail_tech_info.html

They cost less than EUR100/USD150 and have 1% accuracy.

The "SO" output can be hooked up to a parallel or serial port and
you can accumulate and read the number of pulses using the PPS-API,
giving you, in this case, 500mWh resolution.

Poul-Henning

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@xxxxxxxxxxx | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
_______________________________________________
freebsd-arch@xxxxxxxxxxx mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-arch
To unsubscribe, send any mail to "freebsd-arch-unsubscribe@xxxxxxxxxxx"

Relevant Pages

  • Re: Speed Step and powerd for servers status?
    ... I would like to use powerd and speed step for my servers, and make sure it will use the MAX CPU if needed then go to idle mode to save the power. ... This "race to idle" concept stems from the power consumption of an idle processor being much lower than an active processor, even if running at a lower speed. ...
    (freebsd-current)
  • Re: Status of X86_P4_CLOCKMOD?
    ... Especially C2 vs. C2 + throttling? ... Power consumption when "skipping instructions" ... This means that if the processor idle percentage is _larger_ than (1 - ... the fan, and where the latency induced by throttling doesn't matter. ...
    (Linux-Kernel)
  • Re: saving power in a Dell Poweredge 750.
    ... days and it uses 88 watts. ... If it was just sitting ... idle then I would expect the power consumption to be fairly close ... If you want to see peak power consumption, ...
    (freebsd-stable)
  • Re: CONFIG_SUSPEND and power consumption
    ... Sempron 2600+) was running at a much lower temperature when ... Measuring the power consumption of my system confirmed that the energy ... (idle), while with CONFIG_SUSPEND=y, the system consumes only 69 W! ...
    (Linux-Kernel)
  • Re: system idle process
    ... It's an indication of how much more the processor could do if you ... > the cpu usage. ... > even know what the system idle process is for. ...
    (microsoft.public.win2000.general)