  In many embedded real-time systems, applications often interact with I/O
devices via read/write operations, which may incur considerable suspension
delays. Unfortunately, prior analysis methods for validating timing correctness
in embedded systems become quite pessimistic when suspension delays are
present. In this paper, we consider the problem of supporting two common types
of I/O applications in a multiprocessor system, that is, write-only
applications and read-write applications. For the write-only application model,
we present a much improved analysis technique that results in only O(m)
suspension-related utilization loss, where m is the number of processors. For
the second application model, we present a flexible I/O placement strategy and
a corresponding new scheduling algorithm, which can completely circumvent the
negative impact due to read- and write-induced suspension delays. We illustrate
the feasibility of the proposed I/O-placement-based schedule via a case study
implementation. Furthermore, experiments presented herein show that the
improvement with respect to system utilization over prior methods is often
significant.
