Date: Thu, 22 Mar 2012 10:51:09 +0100 From: Alexander Leidinger <Alexander@Leidinger.net> To: Luigi Rizzo <rizzo@iet.unipi.it> Cc: Matthias Gamsjager <mgamsjager@gmail.com>, freebsd-stable@freebsd.org, John <john@theusgroup.com> Subject: Re: powerd and increase in energy need Message-ID: <20120322105109.Horde.srohf5jmRSRPavYNP_frKBA@webmail.leidinger.net> In-Reply-To: <20120321173728.GA41322@onelab2.iet.unipi.it> References: <CA%2BD9Qhv5EmrkqvLetx9T5WD_1BRuCpUyZ=VYnRSjwRYqA7phdg@mail.gmail.com> <20120321000058.177F8256@server.theusgroup.com> <CA%2BD9QhsMMXYbLKg__jZx=7KbCHtK6LjqkfL9WSWs=pdT-t9r0w@mail.gmail.com> <CAN6yY1tKYbTjgQsL1gnfrc9r68c%2BQDCb1SAb%2BM=RFA90jvLpnw@mail.gmail.com> <20120321173728.GA41322@onelab2.iet.unipi.it>
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Quoting Luigi Rizzo <rizzo@iet.unipi.it> (from Wed, 21 Mar 2012 18:37:28 +0100): > I guess that the credit for power saving goes mostly to the CPU > architects. Powerd only gives second-order savings, and C1 vs. C3 > is ineffective, at least for HZ=1000 > > CPU Power (watts) > freq idle 16 threads > ----------------------- > 200 48 51 > 2200 52 83 > 3200 54 115 > 3401 56 118 > > powerd 48 118 I hope you all don't use a cheap PSU, but a _good_ high efficient one, which really draws less power when idle instead of generating heat. Some PSUs are only efficient in a sweet spot, instead of being efficient over a broad range, even when being idle. See http://en.wikipedia.org/wiki/80_PLUS for a quick and not so in-deep overview (and the reality may differ from manufacturer to manufacturer). Bye, Alexander. -- That does not compute. http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7 http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137
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