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Re: [vox-tech] weird boot message
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Re: [vox-tech] weird boot message



ME wrote:
> 
> On Mon, Oct 29, 2001 at 08:35:05AM -0800, Aaron King wrote:
> > I've got Mandrake 8.1 running on my Celeron 700 MHz laptop and, while
> > staring stupidly at the login message one morning, I noticed that it
> > reported a 197 MHz CPU.  This morning, it says it lives on a 287MHz
> > CPU.  This is what dmesg says as well.
> 
> Some CPUs boards have power saving features used to throttle the speed of
> the CPU (mostly laptops where power savings is an issue).
> 
> Check in your BIOS and see about disabling some power management
> capabilities, or forcing your CPU to not save power by slowing down. Many
> new laptops have worked with windows with this to allow special access
> from the OS to throttle the speed of the CPU. It is possible that apmd has
> access to this, or apm support in your kernel allows for apmd to talk to
> your system, but this is just a blind guess.
> 
> If you are not controlling this, then your hardware may be misinterpreting
> inforation from the kernel/a service as requests to change the speed of
> the CPU.
> 
> When you see these messages, are you coming from windows (having left
> windows) a cold boot, warm reboot, ?
> 
Been experimenting.  The current working hypothesis is that on reboots
(warm or cold) when on battery, the CPU is reported as slow.  When
booting while on AC, the full clock rate is reported.  I've found a few
settings in the BIOS which might affect this behavior.  I can set up the
power mode for "maximum performance" as opposed to "maximum battery
life".  I set this to "maximum performance" and get full 697 MHz even
when booting off the battery.  This does not appear to be fully
repeatable: I returned the BIOS setting to "maximum battery life" and
rebooted, /proc/cpuinfo reads 697 MHz.  

There is also a "CPU power management" feature in the BIOS which
apparently "stops the microprocessor clock automatically when there are
no system activities".

But first things first: is there any reason to believe this is something
I should worry about?  Might I be taking a performance hit for the life
of the session?  What depends on /proc/cpuinfo?



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