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Re: KDE changing system time

Russell Coker <russell@coker.com.au> wrote:

There's a discussion on the OxLug mailing list where people are saying that KDE messes with the system clock and Debian developers know about this.

What is it?

I've been running the latest Debian/unstable for the last 6 weeks with SE Linux banning such time changes and my logs indicate that KDE hasn't tried anything.

This is the result the logical fallacy of arguing from the "specific' to the "general", IMHO. The people who are making such "authoritative" statements probably started using KDE and noticed the system time was off about the same time. They connected the dots and began making proclaimations without much further research.

I have experienced this phenomena long before KDE became a reality! As it turns out, it is a function of several other factors at the hardware and OS level.

1. The hardware "clock" on the MB isn't always as stable a reference as one would assume. Bad design without too much consideration of inherent drift, and sometimes a failing power source on the BIOS make them poor time pieces over the long run. If you buy a "cheap" MB, then you probably are buying a poor timepiece in the bargin. You HAVE to correct the BIOS settings periodically, just like you have to set your wrist watch occasionally!

2. The system clock is run in the OS and is quite different from the "hardware" clock on the MB. It is a much less stable reference than the hardware clock and is normally synched with the hardware clock on bootup. On shutdown the two times are again compared, a drift rate is computed, and this drift rate is applied to the system clock the next time the computer is booted. IIRC, heavy disk usage and other OS functions can cause the system clock to miss a few beats, which accumulate over time and can cause a highly variable estimate of that drift rate on shutdown. Things that make heavy use of system resources will exacerbate this phenomena (KDE, X, large file transferes to & from the HD, compiling a kernel, graphics, etc.).

3. The longer your computer is "up" the bigger these differences between the two clocks become, unless corrected periodically. Servers, routers, and others with long "uptimes" are particularly prone to large time errors unless corrected.

I could go on into finer details, but you get the idea. We are dealing with an imperfect time keeping method to begin with, and it is ludicrous to state/or imply that KDE is the sole cause!

The fix to all this is to synch your computer(s) with an external, stable time reference. You can do this manually if you want, but it is quite easy to do it automatically. I have set up one of my LAN computers as a local time-server that is synched to an external time-reference and then I synch all my other LAN compters to my local time server. I have been running this config for over a year, while using KDE exclusively on all the computers, and I have NEVER had any problems nor seen "KDE messes with the sytem clock".

I would not place such people in a position of authority....

-Don Spoon-

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