Bug 339451

Summary: Wrong time (may be clock speed?)
Product: [openSUSE] openSUSE 10.3 Reporter: Valentin Balt <valentin>
Component: KernelAssignee: E-mail List <kernel-maintainers>
Status: RESOLVED FIXED QA Contact: E-mail List <qa-bugs>
Severity: Normal    
Priority: P5 - None CC: forgotten_GqVoGY8DvD
Version: Final   
Target Milestone: ---   
Hardware: x86-64   
OS: openSUSE 10.3   
Whiteboard:
Found By: --- Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---

Description Valentin Balt 2007-11-06 09:23:15 UTC 
1. I set up my clock (use localtime)
2. NTP is disabled

My clock is speed up and go ahead with 10, 15 minutes and more every hour or frequently. So, i have a difference with ~3 hours (ahead) after ~3 days of uptime.

3. I set up my clock again
4. Enable NTP

The situation is equal to previous.

My hardware:

Intel Pentium D 2.8GHz

In result, i have to sync my clock every day with my cellular or any other more accuracy clock system :)
Comment 1 Valentin Balt 2007-11-06 09:25:45 UTC 
I have not this error in previous version (openSUSE 10.2).

I upgrade to 10.3 with fresh install (with system partition format).
Comment 2 Valentin Balt 2007-11-06 13:11:35 UTC 
So, after 5 min thinking about this problem:

I shut off an automatic System Speedup tecnology (N.O.S. by Asus in BIOS) and my clock remain accuracy now!

But! The Bug is still open.
Comment 3 Forgotten User GqVoGY8DvD 2008-01-20 18:12:27 UTC 
The system clock depends on CPU timing clocks. If the CPU clock varies, so will the system clock. What is really needed is for the kernel to optionally read the hardware clock for such systems, especially since variable clocked systems are becoming far more common. Really no excuse now since hardware clocks are also more accurate, generally.

Crude workaround:

1. Use cron to periodically reset the system clock:
     #/sbin/hwclock --hctosys 
      (use option  --utc if your hwclock is set to UTC.)

      I reset my system clock every minute. My typical drift
       is -3 seconds per minute. 

      This works if your hardware clock is accurate, which it should be. Else, 
      use NTP or rdate to reset the clock frequently but not more frequently 
      the server's policy allows, of course.

2. In /etc/sysconfig/clock. change the following line:
     SYSTOHC="yes"

   to

     SYSTOHC="no"

        to keep the system from writing the wrong time to the hardware 
         clock on shutdown. 
        

3. YMMV

4. $SYSTOHC apparently not available until 10.2.

Or, disable SpeedStep, PowerNow, or whatever clock speed changing method is used, in BIOS settings, if possible. This will noticeably shorten the battery run time on laptops, etc.
Comment 4 Greg Kroah-Hartman 2008-02-04 21:44:58 UTC 
Closing due to workaround being available.