Date: Fri, 08 Apr 2011 17:53:36 +0100 From: Daniel Gerzo <danger@FreeBSD.org> To: Alexander Motin <mav@FreeBSD.org> Cc: stable@FreeBSD.org Subject: Re: powerd / cpufreq question Message-ID: <85cda6f83d328e67a552b2cd5758dbd3@rulez.sk> In-Reply-To: <4D9F2384.5000104@FreeBSD.org> References: <4D9EEDAF.3020803@rulez.sk> <4D9EF48C.9070907@FreeBSD.org> <e229a6a374fdd5a626c0b777752fef54@rulez.sk> <4D9F2384.5000104@FreeBSD.org>
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On Fri, 08 Apr 2011 18:02:28 +0300, Alexander Motin wrote: >> OK, I understand what you are saying here. On the other side, I know >> pretty well how the load is distributed - in this particular case, >> the >> box is a web server, running ~30 php-cgi processes. >> This kind of operation doesn't require very high frequency and I >> suspect >> the cores are never waiting for each other. There could be an option >> which would allow an administrator to decide whether this is the >> case >> and allow him to set a higher -r and -i values, what do you think? > > I think it should be possible with minimal changes. So, here is my attempt to implement it: http://danger.rulez.sk/powerd.diff Can you please review & comment? I should be able to commit it mysqlf if you consider it acceptable. It seems to work for me :) >> >> Any idea what I should look for in the BIOS? > > Something about C-states, or Cx-states on the CPU page. But first > look at dev.cpu.X.cx_supported to make sure it is not already present > and just unused. Seems like it was enabled by default. I have like these: dev.cpu.0.cx_supported: C1/3 C2/96 C3/128 Does that mean I only need to set these in rc.conf?: performance_cx_lowest="C3" economy_cx_lowest="C3" Then run /etc/rc.d/power_profile 0x00? May it cause any instability? >> This is 8-STABLE, any idea whether there's a MFC plan for the extra >> 9-CURRENT bonuses? > > I suppose around May. Do you have some patches? If not you don't really need to make them just for me, I can wait a little. >>> You may want to look here: >>> http://wiki.freebsd.org/TuningPowerConsumption >> >> From reading this, are you reffering above to the C2 states? (seems >> like C3 is not optimal for this kind of operation...) > > The deeper state, the more power saved. To get most of it and to get > TurboBoost working you need at least C3 CPU state (ACPI may report it > with different number). Some latest Intel CPUs have no described > problems with C3 and LAPIC, for others described system tuning > requited. I believe this is pretty recent CPU (6 core Xeon X5650). Do you know about any problems? > PS: Using powerd in best case wont hurt performance, while using > C-states may even increase it in some cases because of TurboBoost. If I want to use C-states, should I stop to use powerd, or is it possible to use them both together? Thanks! -- Kind regards Daniel
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