Le 13 juillet 2016, Lucas Levrel a écrit :
Hi,
I would like to adjust the temperature at which the fan starts, because as it
is now it runs continuously, at low speed but this continuous noise bothers
me. I'd rather have it spin faster and intermittently. This is an HP laptop.
I've read much (mostly Q&A pages and list threads, regular documentation
seems to be scarce), and investigated the behaviour of files in
/sys/devices/virtual/thermal . From what I understand there's no bug, just
the temperature thresholds are not to my taste.
More specifically, there are 7 cooling_device's (4 of type Fan, 2 Processor,
1 LCD) and 5 thermal_zone's (the first 4 really are temperatures, the last is
the fan speed). thermal_zone0 controls the fan. The lowest trip_point_?_temp
(?==4) is 45000, which is very low. Basically, after a few minutes of idle
operation temp reaches 50000 or 55000 (looks like there is 5 °C granularity)
and never gets lower: I've tried and manually set the fan to speed 2 (echo 1
cooling_device2/cur_state), even then temp doesn't decrease below 50000.
trip_point_?_temp are not writable. I've set thermal.act=60000 in the kernel
command line, to no avail; is this supposed to be reflected in the
trip_point_?_temp files? (Note: trip_point_[1-4]_type is "active".) This is
kernel 3.2.71 .
What can you advise me to do now?
And by the way, for my education:
- how are the trip_point values determined?
- how is hysteresis implemented? I mean, you don't want your fan speed to
change every other second, so the "speed up" threshold has to be higher than
the "speed down" one. In fact, I've found no explanation of how the
trip_point values are used.
Thanks.
Hi again,
After investigating some more, I found how hysteresis works: the
trip_point_?_temp changes when it is crossed. In my case,
trip_point_4_temp is 50000 at first (by default), and goes down to 45000
when the fan starts.
This is also why I saw no effect of thermal.act=60000 last time I tested:
during boot the temperature reaches this threshold, and trip_point_4_temp
is set to 45000.
I remain with the following questions:
- how are the trip_point values determined?
- is there a way to set them to taste? More specifically, I would like to
rise the "fan stop" trigger temp; thermal.act= visibly didn't change
this...
Thanks again.
--
Lucas Levrel
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