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Date: 21 Sep 93 14:33:37 GMT
From: cis.ohio-state.edu!magnus.acs.ohio-state.edu!usenet.ins.cwru.edu!howland.
reston.ans.net!pipex!uknet!yorkohm!minster!ken@ucbvax.Berkeley.EDU
Subject: Report available via FTP
Message-ID: <748622017.20183@minster.york.ac.uk>
List-Id: <comp.lang.ada>

A report entitled "Implementing Analysable Hard Real-time Sporadic Tasks in
Ada 9X", by A. Burns and A.J. Wellings is available by FTP from the following 
site:

minster.york.ac.uk (IP address 144.32.128.41)

in the directory:

/pub/realtime/papers

in the file:

YCS209.ps.Z

The file is stored in compressed postscript format so be sure to set binary
mode when FTPing the report. The abstract of the report is as follows:

              In this paper we illustrate how systems containing hard
              real-time  sporadic  tasks  can  be  analysed for their
              worst case  behaviour.   In  order  to  undertake  this
              schedulability  analysis, it is necessary to define the
              minimum  inter-arrival  time  and/or  maximum   arrival
              frequency  of  sporadic tasks. Furthermore, at run-time
              it is essential to ensure that sporadic tasks  are  not
              invoked  more  often  than  has  been guaranteed by the
              analysis. We  assume  that  sporadics  are  invoked  by
              interrupts  and  that  interrupts  can  be masked under
              software control.

                   Sporadic tasks are often analysed using the notion
              of  bandwidth  preserving  sporadic  servers within the
              Rate Monotonic Scheduling Analysis scheme.  At run-time
              this  requires the underlying kernel to support complex
              execution time  monitoring  mechanisms.   Unfortunately
              such  mechanisms are not generally supported by Ada 9X.
              This paper  shows  that  by  using  Deadline  Monotonic
              Scheduling  Analysis  there  is  no  need  to resort to
              bandwidth  preserving   sporadic   servers,   and   the
              facilities available in Ada 9X can be used.

A number of other papers and reports written by the Real-Time Systems
Research Group at York are also available; the file INDEX in the directory
/pub/realtime/papers lists these.

--
Ken Tindell             Internet      : ken@minster.york.ac.uk
Computer Science Dept., Local FTP site: minster.york.ac.uk
University of York,     Tel.          : +44-904-433244         
YO1 5DD, UK             Fax.          : +44-904-432708