Re: system clock speed too high?

I reported this same problem for kernel 2.5.69/70 on pentiumIII with chipset
i810, but it seems the reports has been unnoticed.

I replicated your tests with 2.5.70 without acpi, same results here.

On Tue, 3 Jun 2003, Andreas Haumer wrote:

> Date: Tue, 03 Jun 2003 11:54:26 +0200
> From: Andreas Haumer <[e-mail]>
> To: Alan Cox <[e-mail]>
> Cc: Linux Kernel Mailing List <[e-mail]>
> Subject: Re: system clock speed too high?
>
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> Hi,
>
> Alan Cox wrote:
> > On Llu, 2003-06-02 at 20:40, Andreas Haumer wrote:
> >
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> >>Hi!
> >>
> >>(I've already reported this previously as post scriptum
> >>to a different bugreport, so it might have slipped through
> >>unnoticed...)
> >
> >
> > Does this occur if you boot with "notsc" or if you run a non ACPI kernel
> > ?
> >
> I did some more tests on this machine, with the following
> results:
>
> 1.) Kernel 2.4.21-rc6-ac1 (ACPI compiled as module)
>     a) no special kernel commandline option
>        -> System doesn't boot, fusion MPT driver doesn't find
>           the hardware listed on the PCI bus (problem already
>           reported in a previous mail)
>
>     b) boot with "acpi=off"
>        -> System does boot, fusion MTP driver finds the controller
>        -> time runs 2.5 times too fast
>
>     c) boot with "acpi=off notsc"
>        -> same as 1b)
>
> 2.) Kernel 2.4.21-rc4 (ACPI compiled as module)
>     a) no special kernel commandline option
>        -> System does boot, fusion MTP driver finds the controller
>        -> time runs 2.5 times too fast
>
>     b) boot with "acpi=off"
>        -> Same as 2a)
>
>     c) boot with "acpi=off notsc"
>        -> Same as 2a)
>
> 3.) Kernel 2.4.21-rc2-ac2 (ACPI compiled as module)
>     a) no special kernel commandline option
>        -> System doesn't boot, fusion MPT driver doesn't find
>           the hardware listed on the PCI bus
>
>     b) boot with "acpi=off"
>        -> System does boot, fusion MTP driver finds the controller
>        -> time runs 2.5 times too fast
>
>     c) boot with "acpi=off notsc"
>        -> same as 3b)
>
>
> 4.) Kernel 2.4.21-rc6-ac1 (without ACPI)
>     a) no special kernel commandline option
>        -> System does boot, fusion MTP driver finds the controller
>        -> time runs 2.5 times too fast
>
>     b) boot with "notsc"
>        -> Same as 4a)
>
> 5.) Kernel 2.4.21-rc4 (ACPI compiled as module)
>     floppy-minisystem, booting into initrd only
>     modules loaded: unix.o. ext2.o, floppy.o
>     -> time runs 2.5 times too fast
>
>
> Time "acceleration" always seems to be by a factor of exactly 2.5
> Proof:
> root@setup:~ {502} $ ntpdate ntp.xss.co.at; sleep 300; ntpdate ntp.xss.co.at
>  3 Jun 11:31:52 ntpdate[1185]: step time server 194.152.162.17 offset -895.898772 sec
>  3 Jun 11:33:52 ntpdate[1187]: step time server 194.152.162.17 offset -180.088187 sec
>
> (I first sync the system clock with our NTP timeserver, then sleep
> 300 seconds, and then again sync against our NTP server)
>
> Sleeping 300 "system seconds" takes 120 "wall clock seconds" and
> brings the system clock ahead of 180 seconds, which gives a speed
> up factor of 2.5. Does this number ring any bell?
>
> Additional info: I'm booting with LILO and have set LILO timeout
> to 10 seconds. This works fine: "LILO time" is the same as wall
> clock time. So this speed up must be triggered somewhere inside
> the kernel, it seems...
>
> Any idea someone?
>
> - - andreas
>
> - --
> Andreas Haumer                     | mailto:[e-mail]
> *x Software + Systeme              | http://www.xss.co.at/
> Karmarschgasse 51/2/20             | Tel: [phone]
> A-1100 Vienna, Austria             | Fax: [phone]
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