On 3 Oct, Willem Jan Withagen wrote: > On 2-10-2015 23:32, Don Lewis wrote: >> On 2 Oct, Willem Jan Withagen wrote: >>> >>> Hi >>> >>> 10.2-STABLE FreeBSD 10.2-STABLE #0 r287102: Mon Aug 24 >>> >>> Processor: Opteron 6812, in Supermicro H8SGL >>> >>> dev.cpu.7.temperature: 11.1C >>> dev.cpu.6.temperature: 11.1C >>> dev.cpu.5.temperature: 11.1C >>> dev.cpu.4.temperature: 11.1C >>> dev.cpu.3.temperature: 11.1C >>> dev.cpu.2.temperature: 11.1C >>> dev.cpu.1.temperature: 11.1C >>> dev.cpu.0.temperature: 11.1C >>> >>> But I'm pretty sure it is not 11.1C in the datacenter.... >>> >>> Or should I not use amdtemp.ko for this? >> >> The definition of the value that can be read from the temperature >> register is pretty strange. For AMD Family 15h processors, the BIOS and >> Kernel Developer's Guide (BKDG) says this: >> >> Tctl is a processor temperature control value used for processor >> thermal management. Tctl is accessible through D18F3xA4[CurTmp]. >> Tctl is a temperature on its own scale aligned to the processors >> cooling requirements. Therefore Tctl does not represent a temperature >> which could be measured on the die or the case of the processor. >> Instead, it specifies the processor temperature relative to the >> maximum operating temperature, Tctl,max. Tctl,max is specified in the >> power and thermal data sheet. Tctl is defined as follows for all >> parts: >> >> A: For Tctl = Tctl_max to 255.875: the temperature of the part is >> [Tctl - Tctl_max] over the maximum operat- ing temperature. The >> processor may take corrective actions that affects performance, such >> as HTC, to support the return to Tctl range A. >> >> B: For Tctl = 0 to Tctl_max - 0.125: the temperature of the part is >> [Tctl_max - Tctl] under the maximum operating temperature. >> >> It would be nice to report Tctl_max so that we could at least know how >> far the temperature is from the limit, but I don't know if that is >> available. It might be the value in the HtcTmpLmt register, but the >> BKDG is unclear about that. If not, we would have to build a table of >> values from the datasheet. > > And > > On 2-10-2015 23:06, Jung-uk Kim wrote: >> On 10/02/2015 16:49, Willem Jan Withagen wrote: > >> amdtemp(4): >> >> For Family 10h and later processors, ´(the reported temperature) is a >> non-physical temperature measured on an arbitrary scale and it does not >> represent an actual physical temperature like die or case temperature. >> Instead, it specifies the processor temperature relative to the point at >> which the system must supply the maximum cooling for the processor's >> specified maximum case temperature and maximum thermal power dissipation¡ >> according to BIOS and Kernel Developer's Guide (BKDG) for AMD Processors, >> http://developer.amd.com/documentation/guides/Pages/default.aspx. > > If one boots into the BIOS, the BIOS suggests that it knows how to do > this conversion.... Perhaps one can question the ultimate correctness of > the outcome, but the 51.3C value suggests some accuracy. That may be a measurement from a separate temperature sensor on the motherboard underneath the CPU socket. > Thusfar I have not been able to locate the "Power and Thermal Datasheet" > for the family 15h.... > Perhaps need to disassemble the bios, or check other tools or OSes on > how they do this. > > --WjW >Received on Tue Oct 06 2015 - 02:28:48 UTC
This archive was generated by hypermail 2.4.0 : Wed May 19 2021 - 11:41:00 UTC