Date: Tue, 18 Mar 2008 19:59:40 +0000 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Brooks Davis <brooks@freebsd.org> Cc: arch@freebsd.org, Robert Watson <rwatson@freebsd.org> Subject: Re: Power-Mgt (Was: Re: cvs commit: src/sys/i386/cpufreq est.c ) Message-ID: <1362.1205870380@critter.freebsd.dk> In-Reply-To: Your message of "Tue, 18 Mar 2008 13:54:35 EST." <20080318185435.GA2853@lor.one-eyed-alien.net>
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In message <20080318185435.GA2853@lor.one-eyed-alien.net>, 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@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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