Date: Tue, 7 Oct 2008 06:28:32 -0700 From: Jeremy Chadwick <koitsu@FreeBSD.org> To: Kirk Strauser <kirk@strauser.com>, FreeBSD Questions ML <freebsd-questions@freebsd.org> Subject: Re: Coretemp seems to be off quite a bit Message-ID: <20081007132832.GA49914@icarus.home.lan> In-Reply-To: <20081007132517.GA31229@melon.esperance-linux.co.uk> References: <F39A6D89-C720-401D-8399-AA0BB644736B@strauser.com> <20081007132517.GA31229@melon.esperance-linux.co.uk>
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On Tue, Oct 07, 2008 at 02:25:17PM +0100, Frank Shute wrote: > On Mon, Oct 06, 2008 at 09:39:40AM -0500, Kirk Strauser wrote: > > > > I have a Gigabyte motherboard with an Intel ICH-9 chipset, and a > > 3.0GHz Core 2 Duo (E8400). The coretemp sysctls seem to always show > > 50C as the baseline temperature: > > > > $ sysctl dev.cpu | grep temp > > dev.cpu.0.temperature: 50 > > dev.cpu.1.temperature: 50 > > > > This is with a big PSU fan, a good CPU fan, a clean heatsink, and two > > case fans aimed the right direction (front fan pulling cool air in, > > rear fan pushing warm air out). If I reboot and go into the BIOS, I > > get numbers around 42-43C. I know it's kind of hard to compare > > directly, but the coretemp numbers are from a totally idle system with > > powerd scaling it back to 373MHz, so it should be as cool as when > > sitting idle in the BIOS screens. When I work the system hard, like > > running "make -j4 buildworld", I see temperatures up around 63-64C, > > and I'm almost positive that's not right. > > > > Any ideas why coretemp and the BIOS would show such different numbers? > > To add some numbers, I've got an E6550 on a Gigabyte GA-P35-DS3L > (ICH9) and I get: > > $ sysctl dev.cpu | grep temp > dev.cpu.0.temperature: 24 > dev.cpu.1.temperature: 28 > > Ambient room temp: 23°C > > That's running powerd and the machine idle, standard heatsink/fan > combo, 1x12cm case fan. > > Your's might run hotter (higher clock speed? Mine: 2.33GHz) but I > wouldn't expect it to run *so* much hotter. > > I'd expect your numbers to be right if all the ACPI stuff is working. Clarification here is needed: coretemp(4) has nothing to do with ACPI. It gets thermal statistics from the processor by talking *directly* to the processor with specific opcodes, the results returned in specific CPU registers. It does not rely on ACPI. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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