[ltp] T61 temperature limits

[Jeffrey Taylor]

Quoting Henrique de Moraes Holschuh <hmh@hmh.eng.br>:
[snip]
> Nice alone can't do that.  You want a process to use less power?  Let it
> end (or sleep) as quickly as possible so that the CPU can go to C3
> ("race to idle").  If it is a long running process where "race to idle"
> doesn't matter (i.e. it doesn't sleep, for example), you either stop it
> for a while and then let it run again for another while (using
> SIGSTOP/SIGCONT for example), or you use nice and tell the cpu speed
> governor to ignore niced loads.
> 
> SIGSTOP+SIGCONT will probably waste less power, but you'd have to
> measure it to know, as that depends on the workload and also on just how
> much time in C3 your CPU will stay when the background process is not
> running.
> 

There is a program to run a program, STOPing and CONTinuing with variable
weighting.  The project is at:
http://sourceforge.net/projects/dutycycle

Source tarball available for download.  It does reduce the temperature.  On my
laptop, kernel builds boost the temperature from around 40C to around 70C.
With dutycycle on the default 50%, temperatures run 55C-60C.

HTH,
  Jeffrey