Re: SpeedStep / Geyserville lockups?
> > > > Is anyone else out there seeing lockups under 2.2.x (2.2.18 here) with a
> > > > PIII SpeedStep (aka Geyserville) chip?
> > > >
> > > > I've had lockups over the past week I suspect are due to CPU step-speed
> > > > changes resulting from power source switching.
I believe that Speedstep machines are much more stable if they are always
(re)booted while attached to wall power. Suspends and resumes should behave
much better, but *those* depend on whether your APM BIOS is crappy :(
The reasoning is, boot time is when the kernel measures its bogomips, to
figure out what sorts of timings to use for hardware-driver matters.
If you start at say, 500 MHz, but later go to 800 MHz, then your bogomips
are too low and something critical may not wait long enough during an
otherwise inocuous device reset or command. Oops, panic, whatever. You can
get lucky a lot before it fails for "no reason". Bad juju.
I personally suspect that some things may not be all that well behaved "at
the wrong speed" too but I have no direct experience with that.
> > > isn't there an option in the bios to banish this 'feature'? I remember
> > > there being reference to this in a couple of places. Once disabled I
> > > guess you could solely use 'CPU Idle' calls to cool your cpu, which I
> > > assume has the same *effect*.
> >
> > There is.
> >
> > I've set CPU speed to "maximum" (forget the precise opts, believe they're
> > max, min, auto, reverse). System's been up for 19 hours w/o problems,
> > previously I was lucky to get an hour.
> >
> > Note also that SpeedStep is probably more useful under an OS which
> > doesn't have preemptive multitasking. My understanding of Win9X/ME was
> > that it ran at full tilt unless specifically idled, this information
> > coming from VMWare experiences. NT/2K and GNU/Linux have an idle cycle
> > which actually idles the CPU.
> >
> > What's the CPU Idle call you're referringn to?
>
> That's the APM idle, enable it in the BIOS config so the kernel will tell
> the BIOS when it is idle. The ordinary idle you're talking about is when
> the kernel runs the halt instruction, which does indeed keep the CPU cool
> (and save a lot of power if your CPU takes most of the power in the system)
> but the BIOS will never know to go into sleep mode.
One of the better arguments around for building your very own kernel...
* Heather Stern * star@ many places...
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