Subject: Re: RTC and clocks
To: None <port-i386@NetBSD.org>
From: Peter Seebach <seebs@plethora.net>
List: port-i386
Date: 09/18/2006 20:46:50
In message <20060919014047.GO29625@bcd.geek.com.au>, Daniel Carosone writes:
>My guess: you're running current, on a laptop with some form of
>speedstep, and for a time you had a kernel that used the TSC
>timecounter without paying attention to the fact that the cpu clock
>rate changes the tsc clock rate on your cpu. There was a relatively
>short time-window in current when this would happen on some machines.
>You might even find that 35:60 is pretty close to the ratio of the cpu
>idle:max frequencies.
That seems quite possible. I am running current, on a laptop with speedstep,
and I seem to be using TSC. However:
1. There were other ranges; I might lose a second per minute for an hour or
two. It was fine shortly after a reboot. It didn't seem to correlate at all
to system load.
Also:
>> I replaced the laptop's CMOS battery, and this no longer happens.
>I suspect this is a coincidence, and a kernel update was what actually
>fixed the problem (by using the acpi or some other stable timecounter
>instead).
Nope! I left the kernel alone when I swapped the battery. Wanted no
ambiguity.
-s