Re: [PATCH] amd76x_pm on 2.6.0-test9 cleanup

[Charles Lepple]

On Tuesday, November 4, 2003, at 03:05 PM, Tony Lindgren wrote:

> * Charles Lepple <clepple@xxxxxx> [031104 11:45]:
> > On Tuesday 04 November 2003 02:15 pm, Tony Lindgren wrote:
> > > I've heard of timing problems if it's compiled in, but supposedly 
> > > they
> > > don't happen when loaded as module.
> >
> > In some of the earlier testX versions of the kernel, I did not see any
> > difference between compiling as a module, and compiling into the 
> > kernel. (It
> > is currently a module on my system.)
> >
> > I did, however, manage to keep ntpd happy by reducing HZ to 100. Even 
> > raising
> > HZ to 200 is enough to throw off its PLL. The machine is idle for 90% 
> > of the
> > day, though, so I don't know if the PLL is adapting to the fact that 
> > the
> > system is idling, but the values for tick look reasonable.
>
> Interesting, sounds like the idling causes missed timer interrupts? 
> Can you
> briefly describe what's the easiest way to reproduce the timer 
> problem, just
> change HZ to 200 and look at the system time?

At HZ=200, it would take a while to notice. I used adjtimexconfig, 
which counts the number of kernel ticks which occur in 70 seconds 
(according to the RTC). The RTC is pretty stable without power 
management, so I tend to trust it. I think I ended up with a value of 
tick=11000 (compensation for a 10% slow clock), and if I left the 
machine idle, ntpd would converge based on the new tick value.

Then again, I don't think I tried HZ>=200 on -test9. (When I got Pasi's 
-test9 patch, I applied it to a -test8-bk kernel with HZ=1000-- I don't 
remember exactly which one.) Based on his followup email, timekeeping 
may be better in -test9. I'll check.

> I've been using kexec for reboots recently though as the bios reboot 
> is soo slow.

The slowness on my system is supposedly related to ECC initialization, 
but it's only ~30 seconds for 512MB. Still, if I upgrade the memory, 
that's a good tip.

> But just to verify: 2.6.0-test9 & amd76x_pm as module, and the system 
> drops
> into sleep mode when the module is loaded for the first time until 
> power is
> pressed? And this does not happen after cold reboots or when the 
> amd76x_pm
> is reloaded?

Correct.

--
Charles Lepple
clepple@xxxxxx

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