Bogus turbo mode with Intel(R) Core(TM)2 Duo CPU P9700 (2.80GHz)
Ian Smith
smithi at nimnet.asn.au
Sat Nov 26 13:17:21 UTC 2016
On Fri, 25 Nov 2016 21:16:11 -0700, Jakub Lach wrote:
> Hello,
Hi. Replying to this 'cos your later response to Adrian got .. nobbled.
> Since I'm running this CPU, I've noticed there is additional
> field in supported frequency (under heavy load)-
>
> dev.cpu.0.cx_supported: C1/1/1 C2/2/1 C3/3/57
> dev.cpu.0.freq_levels: 2801/35000 2800/35000 2450/30625 2133/23888
> 1866/20902 1600/15000 1400/13125 1200/11250 1000/9375 800/12000 700/10500
> 600/9000 500/7500 400/6000 300/4500 200/3000 100/1500
> dev.cpu.0.freq: 2801
> dev.cpu.0.temperature: 67,0C
>
> as far as I know, the +1 MHz mode is a turbo boost factory
> overclock, however this CPU does not support it. Anybody knows
> what's going on?
>
> I've previously had T9400 (2.53 GHz), there was no such thing listed
> and it was running slightly cooler under load, despite having higher
> TDP (however P9700 is a lot cooler when idle, as expected).
>
> Still, I don't think it is possible it's actually being overclocked?
My X200 has an Intel(R) Core(TM)2 Duo CPU P8600 @ 2.40GHz, less than a
year older than yours, still Penryn. Last time I explored this on the
Intel site it didn't do Turbo Boost as such but it did do some earlier
version of that; sorry I forget its name or details, and ark.intel.com
seems different from what I found then. No time to hunt now.
In a message to freebsd-mobile@ on 4 Feb 2015, in response to mine
Warner Losh advised:
> > On my X200 it's '2401/35000 2400/35000 1600/15000 800/12000' and I
> > found hiadaptive rather aggressive, where adaptive works fine for
> > my use - but of course everybody's use is different :)
> >
> > powerd_flags="-a adp -b adp -i 70 -r 90"
>
> The X+1 number (in this case 2401) is the turbo-mode speed. If you
> use X, it disables the Turbo mode which causes the CPU to run faster
> until it gets too hot. On my T400, I found that if I limit powerd to
> X instead of X+1, I have fewer heat related issues when Im doing
> things like building a kernel
>
> Warner
So I've run powerd with flag '-M 2400' since without issue either way.
But then, I'm doing many timing runs where consistent CPU speed at load
is a virtue, and I recall it definitly ran somewhat cooler at full load.
Not that 67C is particularly hot; running say sysutils/stress with '-c 4
-t 20m' gets my X200 to >80C in warmer weather, but the fan holds it ok.
cheers, Ian
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