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Miscellaneous => Technical Support => Topic started by: H_TeXMeX_H on 20 March 2006, 20:43

Title: System time runs twice normal speed on FC4 SMP kernel
Post by: H_TeXMeX_H on 20 March 2006, 20:43

On my desktop:

Pentium 4 HT 3.02 Ghz
1 GB RAM
SiS chipset
Nvidia GeForce 4 Ti graphics card

The system time runs twice as fast as normal running the Fedora Core 4 SMP kernel and Hyper-threading support on (2 seconds system time = 1 second real time). The problem goes away if I turn HT off and go to non-SMP kernel ... but it runs 20-40% slower than with HT on and SMP, so I leave HT on and use SMP. It doesn't bother me too much, with a few exceptions such as the delay times are all 1/2 as long as they should be so if I hold a key down for just a bit too long it'll quickly fill the page with that character, and hotkeys are problem like when I want a terminal it's hard to get just 1 terminal to pop up ... usually 10-20 pop up :( Anyway ... I've posted this question in other places and it looks like it happens on other distros as well ... like Ubuntu and Suse and others, and that there is no real solution ... it just a kernel bug. I hope this is not the case :( I don't have access to my desktop right now ... it's at my other house ... so I can't try out things to see if they work, but as soon as I get access I'll try to implement the solutions ... maybe I could set up some remote desktop stuff.

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: Lead Head on 20 March 2006, 21:01

I have even heard of similar bugs with Windows and hyper thread, to me it looks like you are going to have to live without HT and SMP:(

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: piratePenguin on 20 March 2006, 22:22

Sounds like a major kernel bug.
I'd try compiling 2.6.16 (just released today). There's new SMP fixes in basically every linux release...

Do all people with P4 HT have this problem?

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: WMD on 20 March 2006, 22:43

Quote from: piratePenguin

Do all people with P4 HT have this problem?

Not me.

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: Aloone_Jonez on 20 March 2006, 22:50

Cool, does everything else run at twice the speed? :D

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: KernelPanic on 21 March 2006, 00:30

I think you need to pass disable_timer_pin_1 as an arguement to your kernel.

Test that it is fixed by running:
time sleep 10

Which should take 10 seconds of real time.

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: mobrien_12 on 21 March 2006, 01:37

Once you get your system time under control, you probably should set up ntpd anyway.

Atomic clock accuracy ROX!

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: H_TeXMeX_H on 21 March 2006, 03:56

Quote from: KernelPanic

I think you need to pass disable_timer_pin_1 as an arguement to your kernel.

Test that it is fixed by running:
time sleep 10

Which should take 10 seconds of real time.

ok how do I do that ? how do I pass commands to the kernel ? just type it in the console ?

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: Aloone_Jonez on 21 March 2006, 10:58

I don't know, as an educated guess I think he means you alter the bootloader configuration file where it loads the kernel, this will depend on whether you use Grub or Lilo.

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: piratePenguin on 21 March 2006, 17:07

Yea. If you use grub, add to the kernel line 'disable_timer_pin_1' in /boot/grub/menu.lst

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: H_TeXMeX_H on 21 March 2006, 21:07

Ok, I'll do that thanks ...

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: H_TeXMeX_H on 15 May 2006, 06:01

The newer kernel versions fix this (at least on my computer)

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: hm_murdock on 24 July 2006, 08:16

Clock runs at twice speed?

Cool.

Title: Re: System time runs twice normal speed on FC4 SMP kernel
Post by: H_TeXMeX_H on 24 July 2006, 20:30

well it did with the older smp kernels ... not anymore ... it wasn't as cool as you think, pretty much anything reliant on the system clock ran twice as fast ... no wonder some of the games I played at the time seemed rather difficult.