Date: Thu, 24 Feb 2005 13:11:14 -0800 From: Nate Lawson <nate@root.org> To: Maxim Sobolev <sobomax@portaone.com> Cc: current@FreeBSD.ORG Subject: Re: patch: p4tcc and speedstep cpufreq drivers Message-ID: <421E42F2.6010105@root.org> In-Reply-To: <421DA0B5.4060705@portaone.com> References: <20050224011924.992A65D07@ptavv.es.net> <421DA0B5.4060705@portaone.com>
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Maxim Sobolev wrote: > Kevin Oberman wrote: >> No joy. I set it to 262 and it was fine. The next step killed the system >> again. >> >> I'm also concerned that taking TCC out of automatic mode might not be a >> great idea, at least until things like _PSV are supported. When I do a >> buildkernel, buildworld or any big compile job, I need to slow down the >> CPU to keep the CPU form frying. It quickly jumps to 185 F. or higher if >> I don't. If I understand automatic TCC, it should throttle the CPU all >> by itself to prevent this. > > > Taking TCC out of automatic mode doesn't disable thermal controlling > circuitry completely, so that if the processor overheats it will shut > down the machine anyway: > > --- > Regardless of enabling of the automatic > or On-Demand modes, in the event of a catastrophic cooling failure, the > processor will > automatically shut down when the silicon has reached a temperature of > approximately > 135 °C. At this point the system bus signal THERMTRIP# will go active > and stay active > until RESET# has been initiated. > --- Correct. Even more so, automatic mode continues to override On-Demand mode if there is a more moderate thermal condition than THERMTRIP#: "On-Demand mode may be used at the same time Automatic mode is enabled, however, if the system tries to enable the TCC via On-Demand mode at the same time automatic mode is enabled AND a high temperature condition exists, the duty cycle of the automatic mode will override the duty cycle selected by the On-Demand mode." Since automatic mode is set by the BIOS before we even boot, things should be fine. >> Between throttling and frequency adjustment I can get about 16 >> performance levels and I don' see a good reason for another 15. Also, >> the change is frequency is so non-linear that small changes often don't >> make sense. The first three step are fairly straight, but then things >> get bumpy. It looks to me like all frequency settings are not created >> equal. > > I wonder this too. I think in the presence of several independent > regulators we need some form of calibration to get more or less precise > results. You can manually test this kind of stuff by doing: hint.p4tcc.0.disabled="1" -- Nate
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