From: Jerry Van Baren <gerald.vanbaren_at_smiths-aerospace.com>
Date: Thu, 06 Mar 2003 07:53:40 -0500

There is a high resolution timer patch for linux:
   http://www.ittc.ku.edu/utime/
Also included in KURT:
   http://www.ittc.ku.edu/kurt/

It works very well. I don't know if it has been accepted into the
mainstream kernel yet.

gvb


At 11:56 AM 3/6/2003 -0500, daniel_at_haxx.se wrote:
>On Wed, 5 Mar 2003, c s wrote:
>
> > While developing a mod to the wps, I noticed that the X11 simulator clock
> > was running much faster than the actual clock does on the Archos.
>
>It certainly does. And it runs differently on different computers as well.
>
>The reasoning behind this is that the simulator will never resemble the
>target when it comes to time or speed. Thus, we've mainly focused in getting
>the timer to run, not to be accurate.
>
> > I wrote a better fix that uses a separate thread that does nothing but
> > increment current_tick every 10ms, however there is a problem with it
> > because on many (most?) Linux systems the shortest wait you can do with a
> > call to poll() (or usleep(), or nanosleep() ) is 20ms. This makes
> > current_tick run at only 50Hz on systems that can't do a suspended wait of
> > only 10ms.
>
>I think you're overdoing the accuracy of the tick slightly.
>
>I think you should do whatever sleep you can do, and then read out the actual
>time it took and increase the tick counter accordingly. Then it doesn't
>matter if your system supports 10, 20 or 200 ms sleep accuracy.
>
> > Also I believe that similar problems exist in the win32 specific simulator
> > code, but I didn't look into details or fixes for the win32 code.
>
>I'm positive the problem is very similar there too, yes.
>
> > Is there any interest in using or improving the other fixes that I have
> > discussed? I have included some of the code that I wrote below if anyonone
> > is interested in the details of what I discussed above.
>
>I don't like the busy-sleep approach, but I'm certainly interested in
>improving this situation.
>
>--
> Daniel Stenberg -- http://rockbox.haxx.se/ -- http://daniel.haxx.se/



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Received on 2003-03-06