[Bug 552020] Re: multi core laptop system overheating, powertop showing a lot [Rescheduling interrupts] <kernel IPI>

[Chris Latham]

On an Acer TravelMate 2500 with Intel Pentium 4 @ 2.80GHz cpu (i.e.
32-bit single core, no hyperthreading) I have been struggling with a
huge power increase since upgrading to Lucid (now with 2.6.32-22-generic
#35-Ubuntu SMP Tue Jun 1 14:17:36 UTC 2010 i686 GNU/Linux).  The battery
life fell from 90 minutes to 30 minutes, the computer became very hot,
and on mains power, the "brick" also became very hot.  The fan
accelerates to top speed within a few minutes of use.  Investigation
with powertop revealed about 90000 (ninety thousand) wakeups per second,
which I spell out in words in case you think I have put too many zeros.

Simply using the nolapic kernel option has reduced the wakeup rate to
about 80 (eighty) per second.  Things seem to be cooling down now, but I
have not yet measured the battery life.  Fan speed is now back to normal
when the computer is idle.

On two other systems, I observe no problems.  These are:

Intel Pentium 4  @ 2.80GHz ( 32-bit single core with hyperthreading)
AMD Athlon K8 LE1600 @ 1-2.2 GHz (64-bit single core)

They experience typically 20-40 wakeups per second.

Clearly, this problem has very serious consequences on some systems.

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multi core laptop system overheating, powertop showing a lot [Rescheduling interrupts] <kernel IPI>
https://bugs.launchpad.net/bugs/552020
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