On Wed, 9 Sep 2009, Alexander Motin wrote: > Daniel O'Connor wrote: > > On Wed, 9 Sep 2009, Alexander Motin wrote: > >> Daniel O'Connor wrote: > >>> I recently discovered a system where the floppy drive cable was > >>> intermittently fouling the CPU fan - I believe this caused the > >>> CPU to overheat and then get throttled by the BIOS. > >>> > >>> Does anyone know if it is possible to determine if this is the > >>> case? ie is there a way to be informed if throttling has > >>> occurred? > >> > >> Theoretically it is possible. I know off-topic tool reporting > >> this. Also you can just monitor CPU temperature, depending on CPU > >> type. > > > > Monitoring CPU temperature is a bit difficult, there are a lack of > > tools (although I have some code it's not complete). > > There indeed problems with MB monitoring, as it is non-standard. But > modern CPUs also include on-chip thermal sensors. For Core2Duo family > coretemp module works fine and precisely.
Ahh coretemp, I had forgotten about that. I did a test on the bench (on a 7.2 system) here and realised that I can't actually detect throttling. coretemp reported 72 & 78C but the frequency was still 2933MHz. I am pretty sure it would be throttling but I think that works by maintaining the frequency but stalling the CPU some percentage of the time. I have p4tcc loaded (in GENERIC) but it doesn't show up, I only get.. dev.cpu.0.%desc: ACPI CPU dev.cpu.0.%driver: cpu dev.cpu.0.%location: handle=\_PR_.CPU0 dev.cpu.0.%pnpinfo: _HID=none _UID=0 dev.cpu.0.%parent: acpi0 dev.cpu.0.freq: 2933 dev.cpu.0.freq_levels: 2933/35000 2566/30625 2199/26250 1833/21875 1466/17500 1099/13125 733/8750 366/4375 dev.cpu.0.cx_supported: C1/0 C2/85 dev.cpu.0.cx_lowest: C1 dev.cpu.0.cx_usage: 100.00% 0.00% dev.cpu.0.temperature: 44 dev.cpu.1.%desc: ACPI CPU dev.cpu.1.%driver: cpu dev.cpu.1.%location: handle=\_PR_.CPU1 dev.cpu.1.%pnpinfo: _HID=none _UID=0 dev.cpu.1.%parent: acpi0 dev.cpu.1.cx_supported: C1/0 C2/85 dev.cpu.1.cx_lowest: C1 dev.cpu.1.cx_usage: 100.00% 0.00% dev.cpu.1.temperature: 36 I see some odd results if I disable the fan while running 'dd if=/dev/zero bs=128k count=5000 | md5' in a loop. The throughput seems to remain the same (odd) but the CPU idle time goes up when it gets hot. > > The problem is that the CPU temperature is only a proxy > > measurement, I would much prefer to be told directly the BIOS is > > throttling rather than guess :) > > While ACPI could implement thermal throttling, AFAIK TM1/TM2 > technologies of P4 and above families are working just in CPU > hardware. BIOS only initializes them. OK. -- Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C
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