L4Linux console using CPU

Adam Lackorzynski adam at os.inf.tu-dresden.de
Thu Jun 23 22:33:15 CEST 2005


On Thu Jun 23, 2005 at 22:25:31 +0200, Bert van Leeuwen wrote:
> Does anybody perhaps know why a DROPS virtual console focused on a L4Linux 
> virtual console uses up CPU time? Is this "normal" behaviour? My DROPS 
> console shows +- 25% CPU usage if the DROPS virtual console is focused on 
> the L4Linux terminal, +- 1% if the DROPS virtual console is focused on 
> something else (e.g. run console). From what I can tell, the thread running 
> the L4Linux virtual console is at priority 0xff, but the main L4Linux task 
> appears to be at default priority 0x10... Is this correct?

If your L4Linx is 2.6 and you're using the l4fb driver, then the driver
periodically refreshes the screen which costs CPU. You can switch that
off by giving "l4fb.refreshsleep=0" at the kernel command line. But then
user programs using the frame buffer (e.g. X) will not display anything.
Maybe giving a bigger value will suit you better.

Adam                 adam at os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/

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