Hi Arun, On Sun, 24 Oct 2010 21:40:38 -0400, Arun Raghavan wrote: > Thanks again for the prompt response. One more question regarding > coretemp: any idea how I can probe the sensor in my own source code? > I'm hoping to be able to probe a few times a second, while the > lm-sensors usage guide says max. probing frequency should be at most > 0.3-0.5 Hz. Out of curiosity, which "usage guide" are you referring to? > I'm trying to measure thermal response and hence > transients. Temperature rises rather too rapidly for this once every > 2-3 seconds restriction; there's no intermediate reading between idle > temperature (~28C) and loaded (~55C). Even when I overclock to > deliberately induce more dissipation, I don't get an intermediate > reading between the same base temperature and 70C! There's no reason why overclocking would help. Overclocking will generate more heat, but the time it takes to generate it won't change. > Please let me know if the 2-3s resolution is a limitation of the > sensors API or the kernel module itself. Any tips on how I might be > able to measure with greater frequency (apart from hooking up an > external probe and thermometer)? There's no limitation at the sensors API level. Each kernel driver has its own cache lifetime depending on various things, including the number of registers to read, how fast or slow register access is, and the driver design. In the case of the coretemp driver, the 1 second lifetime is pretty arbitrary, as there are only a few registers to read (one per core) and register access is very fast (CPU MSRs). Fenghua, Guenter, do you think it would make sense to shorten the cache lifetime to 0.5 or even 0.25 second? Arun, back to your immediate issue, you have two options, either rebuild the coretemp driver with a shorter cache lifetime (replace HZ with HZ/10 in function coretemp_update_device) or access the MSR yourself from user-space (but then you lose all the power of libsensors.) -- Jean Delvare http://khali.linux-fr.org/wishlist.html _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
