From owner-freebsd-stable@FreeBSD.ORG Thu Mar 22 13:59:52 2012 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id B9DAD1065674 for ; Thu, 22 Mar 2012 13:59:52 +0000 (UTC) (envelope-from rizzo.unipi@gmail.com) Received: from mail-iy0-f182.google.com (mail-iy0-f182.google.com [209.85.210.182]) by mx1.freebsd.org (Postfix) with ESMTP id 75D698FC0A for ; Thu, 22 Mar 2012 13:59:52 +0000 (UTC) Received: by iahk25 with SMTP id k25so4144514iah.13 for ; Thu, 22 Mar 2012 06:59:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=O3LqnwuD/uka9Lfz/MavMupC6MeLfZq2gfcMKQDPj2M=; b=TTgiCnWVUPqUQqbjzE/uh8+OqcSC66ozbzSP8gOzky2dOgEptTIcHGWM0KQ1cmxT6j FpK9q3r3Bx/EGNtDH/aK4HQx+Ubvr1EhPyyIzz+Z5Holh/XVVXziZ9v+Vb64rNPcGDl6 LXNMmbx8krPHYq0UFwOWVTLGLTttjWiEdbAcsxCYfARYMjkdnbYOQqZIClJfFWGxfxWy 0wld8OZnDvJM2olhVC/Vgra7ggwe7TFODj6I5E6B2ee77/TS2+IvKw2Nkr1WjSDPAGGu XKQxYUkVRmrQ4WzHaLbR10v4H6YKrvId42cQLKZJJHNTI1rPej4XcESSMwSgngKZVwQi 9cHg== MIME-Version: 1.0 Received: by 10.50.192.134 with SMTP id hg6mr1733155igc.59.1332424786247; Thu, 22 Mar 2012 06:59:46 -0700 (PDT) Sender: rizzo.unipi@gmail.com Received: by 10.42.197.134 with HTTP; Thu, 22 Mar 2012 06:59:46 -0700 (PDT) In-Reply-To: <20120322105109.Horde.srohf5jmRSRPavYNP_frKBA@webmail.leidinger.net> References: <20120321000058.177F8256@server.theusgroup.com> <20120321173728.GA41322@onelab2.iet.unipi.it> <20120322105109.Horde.srohf5jmRSRPavYNP_frKBA@webmail.leidinger.net> Date: Thu, 22 Mar 2012 14:59:46 +0100 X-Google-Sender-Auth: amHqUTdcSw5BLiUEpFpOycQ87jk Message-ID: From: Luigi Rizzo To: Alexander Leidinger Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: Matthias Gamsjager , freebsd-stable@freebsd.org, John Subject: Re: powerd and increase in energy need X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Mar 2012 13:59:52 -0000 On Thu, Mar 22, 2012 at 10:51 AM, Alexander Leidinger < Alexander@leidinger.net> wrote: > Quoting Luigi Rizzo (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). > it isn't such a big deal in my opinion. The %efficiency at low levels is misleading if you don't factor out the 5-10W plateau for keeping the PSU alive (fan, ballast, etc.). See for instance http://www.techpowerup.com/reviews/Antec/HCG-520/5.html the table at the end of the page reports 6.73W of idle power. At 40W this PSU consumes 52.9W, so the apparent efficiency is 75%, but factoring out the idle power you go way up. cheers luigi -- > That does not compute. > > http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7 > http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137 > > -- -----------------------------------------+------------------------------- Prof. Luigi RIZZO, rizzo@iet.unipi.it . Dip. di Ing. dell'Informazione http://www.iet.unipi.it/~luigi/ . Universita` di Pisa TEL +39-050-2211611 . via Diotisalvi 2 Mobile +39-338-6809875 . 56122 PISA (Italy) -----------------------------------------+-------------------------------