Re: [PATCH] amd76x_pm on 2.6.0-test9 cleanup

From: Charles Lepple
Date: Tue Nov 04 2003 - 17:40:22 EST

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?

Weird. On -test9-bk at HZ=1000, with amd76x_pm loaded as a module (lazy_idle=800, the default), the system clock is running fast.

With ntpd running, the clock was stepped back 2.5 seconds twice in 20 minutes.

Here's what I get from adjtimexconfig (after stopping ntpd, of course):

# adjtimexconfig
Comparing clocks (this will take 70 sec)... adjusting system time by -126.211 sec/day

Now tick is 9985. I distinctly remember it being somewhat over 10,000 the last time I ran with HZ=1000 and amd_76x_pm active. With HZ=100, adjtimexconfig sets tick=10002.

I'm not entirely sure what the "acpi" interrupt is doing-- it increments about once every two seconds when the system is idle, and various types of system activity make it happen more frequently. At least I'm not getting any "irq 9: nobody cared!" messages anymore (the button module is loaded, so I guess it is handling it). If I don't have amd76x_pm loaded, the acpi interrupt is triggered a couple of times after button is loaded, but then it doesn't happen again until I actually press a button.

Charles Lepple! clepple

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