Hi Steven! It would of course be optimal to throttle the CPU clock according to the current temperature, but this is exactly what the kernel attempts to do. Unfortunately this approach may fail under heavy load for several reasons (BIOS bugs, bad ACPI implementation, inaccurate sensors, insufficient cooling either by design or through aging, dust, etc.).
Therefore I think it is appropriate to give the user an (expert) option to reduce the CPU clock. It would also be possible to monitor the kernel messages for potential thermal problems (usually something like "temperature above threshold") and to reduce the CPU clock automatically if such messages show up. However, I am not sure if such a behavior should be enabled by default (because even if the temperature is high it might not always be necessary to permanently reduce the CPU clock, thereby unnecessarily degrading the performance). For an expert option concerning the CPU clock, I have thought of the following implementation possibilities: * Find available frequencies and let the user select one of them. * Let the user select 50%, 60%, ..., 100% of the maximum frequency. * Let the user enter the percentage of the maximum frequency to be used. I would prefer the second option, since it should be easy to understand by the user and also simple to implement. What do you think? Cheers, Andreas On 2013-01-16 01:42, Steven Shiau wrote: > Hi Andreas, > Thanks for sharing that. > Your solution is great. For sure it a great feature we should add in the > expert mode. Besides this, I think another option solution is to find a > way to know the temperature is too high then accordingly reduce the CPU > speed. > We should discuss more about this. > Thanks again. > > Steven. > > On 2013/1/16 上午 07:47, Andreas Winkelbauer wrote: >> Dear all, >> >> several users have reported hardware failures with clonezilla due to >> thermal problems, in particular with notebooks (see [1-3]). I also have >> seen these issues with my HP 2540p laptop. It seems that the cooling >> system of some notebooks is insufficient when the system is run at full >> CPU load for an extended period of time (this can be minutes, hours, or >> even days before a shut down to prevent overheating will occur). >> >> Since up to now no solution has been posted here, I'll explain how I >> solved the thermal problems for me. A possible solution is to set the >> CPU to a fixed, lower operating frequency using cpufreq-set from >> cpufrequtils (which is installed by default). This effectively reduces >> heat at the cost of a (relatively small) performance penalty. >> Specifically, what I did was (for a system with 4 CPUs): >> >> $ sudo cpufreq-set -c 0 -f 1600MHz >> $ sudo cpufreq-set -c 1 -f 1600MHz >> $ sudo cpufreq-set -c 2 -f 1600MHz >> $ sudo cpufreq-set -c 3 -f 1600MHz >> >> This worked for me and it should work with all reasonably modern CPUs. >> The current settings and the available frequency steps can be read using >> >> $ cpufreq-info >> >> A few remarks: cpufreq-set automatically rounds the specified frequency >> to the "nearest" available operating frequency (my laptop CPU, e.g., has >> a minimum frequency of 1.2 GHz and a maximum frequency of 2.53 GHz with >> 11 steps in total). However, I have observed that the rounding sometimes >> does not work if -f specifies exactly one of the available frequencies >> (then the next higher frequency might be used instead which seems to be >> a bug of cpufreq-set). Using the above commands, the CPU runs at a fixed >> frequency until changed again or until the next restart. Changes made by >> cpufreq-set are not permanent, i.e., the changes are lost if the system >> is rebooted. >> >> Another way to prevent overheating could be to use "cpulimit", but I >> find it less suited for this particular use case and the corresponding >> package is not installed by default. >> >> @Steven: I could provide a patch for clonezilla-live to include this in >> the expert options. However, we should think about how to implement this >> best. >> >> Cheers, >> Andreas >> >> >> [1] >> http://sourceforge.net/tracker/?func=detail&aid=3090553&group_id=115473&atid=671650 >> [2] >> http://sourceforge.net/projects/clonezilla/forums/forum/663168/topic/3903931 >> [3] >> http://sourceforge.net/projects/clonezilla/forums/forum/394751/topic/3877156
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