Real time response under linux

Graham Perkins (
Tue, 20 Aug 1996 11:31:45 +0100

Hi all,

I am currently working on a project which involves the prediction of the
transmission interval for a number of outstations operating over a UHF
radio link. Each outstation only has the ability to transmit and
therefore cannot determine if the band is currently occupied. The
central receiving station has to determine when each outstation is next
going to transmit and the probability of collisions with other

Due to other requirements, TCP/IP networking etc Linux seemed a
possibility. However, standard Linux only has a timer resolution of 10ms
and lacks the real time response I require. I believe the signal
processing is not performed by the timer interrupt handler but is left
to the scheduler. Exacting when my process gets to execute, after the
signal is processed, is at the mercy of the scheduler. With all these
variable delays prediction is more or less impossible.

If anybody is working on using Linux for real time control or knows how
I could possibly address the above problems I would like to hear from
you. I have considered writing a real time executive which would run
linux as a 'task' - would anybody like to comment?

Thanks to those who respond to this request.

Graham Perkins

Graham Perkins                                  Specialix Research Ltd
Suite 2, Cobb House, 2 Oyster Lane, Byfleet, Surrey, England, KT14 7DU
      Tel: +44(0)1932 35221 ext 432       Fax: +44(0)1932 352349
                 ** Intelligence is only relative **