Subject: Question about speedstep and the est.frequency.target sysctl variable.
To: None <email@example.com, firstname.lastname@example.org>
From: Brian Buhrow <email@example.com>
Date: 08/23/2007 23:56:24
Hello. I've just acquired a Dell Latitude D400 laptop which supports
speestep technology and which appears to have a working speedstep driver
under NetBSD 3.x and 4.x. In attempting to write a powerd script which
reduces the speed of the CPU when the machine is on battery power, I've
noticed something strange.
My script tries to slow the cpu down by setting
machdep.est.frequency.target to the desired value, in my case, 800MHZ.
this appears to work, and the CPU slows down, for a little while, i.e. a
minute or so.
Then, after a minute, the target value climes from 800 back to 1000,
then to 1200, and back to 1400, which is as high as it can go. This
happens without any obvious intervention from me.
Can anyone explain why it is that this value doesn't stay where I set