Date: Wed, 23 May 2007 14:45:55 +1000 (EST) From: Ian Smith <smithi@nimnet.asn.au> To: Ghirai <ghirai@ghirai.com> Cc: freebsd-questions@freebsd.org Subject: Re: notebook cpu throttling Message-ID: <Pine.BSF.3.96.1070523134319.13043A-100000@gaia.nimnet.asn.au> In-Reply-To: <20070522171520.65D5316A46C@hub.freebsd.org>
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On Tue, 22 May 2007 19:35:10 +0300 Ghirai <ghirai@ghirai.com> wrote: [..] > >> I did that, but now xorg constantly uses 20-30% CPU. > >> > >> CPUs were running cooler indeed, but everything ran jerky, > >> because of the xorg cpu usage. [..] > > Point being, if powerd has selected your lowest cpu frequency because > > load is less than default (or as specified by -i and -r switches) and > > this is (say) 1/4 of full speed, then something that normally showed 5% > > cpu will now show as using 20% (of available cpu cycles at that speed) > > > You can tune your powerd idle levels more towards performance, and/or > > you can set a higher minimum cpu freq with sysctl debug.cpufreq.lowest > > from among your available levels. [..] > I suspected this; xorg just reporting to use 20-30% cpu doesn't bother > my, what bothers me is the fact that mouse cursor and everything moves > jerky. > > I'll try to raise the min. freq., maybe powerd lowers it too much.. Maybe. In one recent example, a 1400MHz box (Thinkpad T42p) had freqs all the way down to 75MHz while still running with 1mS slicing (1000HZ) apparently losing i8254 timer interrupts (when using APM, not with ACPI) powerd(8) in adaptive mode with default settings will lower cpu freq one level whenever the load idle is 90% or more, and raise freq (two levels) whenever idle gets less than 65%. Looks like if you set that to say 75% your xorg alone would kick it up. Of course you must be careful not to set the shiftpoints too close together, or you'll observe oscillation .. again, running 'powerd -v' is useful while you're playing with tuning. Re jerkiness, you might also benefit by decreasing the polling interval (how often powerd checks load average) from 500mS to perhaps half that? I'm kinda interested in these fujitsu-siemens laptops myself, so I'm still keen to see your 'sysctl dev.cpu.0.freq_levels' please? Cheers, Ian
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