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Diffstat (limited to 'paper.tex')
| -rwxr-xr-x | paper.tex | 4 |
1 files changed, 2 insertions, 2 deletions
@@ -185,11 +185,11 @@ An TAO ORB can only schedule its CORBA requests correctly, if the underlying ope The operating system should support priorization of device i/o data. The real-time application must not beeing interrupted by incomming traffic on any device, excepted data the real-time application must react on (e.g. digital inputs). On a RT\_PREEMPT enabled linux, the most part of all ISR\footnote{interrupt service routine}s are done in kernel threads, which can be priorized from userspace. This solution has two little cons: IRQ sharing and the softirqs for networking. IRQ sharing prevents from a real per device priorization. The softirqs for networking handle the traffic of all NICs in the system. So the priorization of network data from a specific device is not possible. But in case real-time networking gets more and more important, the community works on a solution for this issue.
-real-time capable network drivers
-
+Not all NICs (especially their firmware and driver) are good for real-time networking. Many modern NICs don't request an interrupt for each received package. They only request an interrupt if a defined amount of data is received, or a defined timeout is over. Esspecially for real-time network communications with little data transfer, these cards causes high latencies.
\section{Conclusion}
+Using an object-orientated middleware for real-time communication over standard ethernet hardware, is especially in the automation industrie, not a trivial thing. But with ACE/TAO and RT\_PREEMPT enabled Linux it is no longer science-fiction.
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