Re: Anyone using Ada with Real-Time Linux?

[Florian Weimer <fw@deneb.enyo.de>]

dmitry@elros.cbb-automation.de (Dmitry A. Kazakov) writes:

> [We are considering which OS platform to choose for an embedded "soft"
> real-time system. Our requirements are: 5 ms for the DAQ & control
> task and almost "no matter" for the TCP/IP tasks]

If the 5ms are a *requirement*, it's not "soft" real time. ;-)
(And you shouldn't use a standard Linux version.)

>>Whether this would fit the requirement I don't know; there might be
>>unavoidable delays, as Dmitry says.
>
> I heard that the Linux kernel is (or will be) preemptive. If so, there
> [I suppose] should be no big problem with I/O?

Usually, I/O isn't the problem.  Some FS operations and console
switching are major offenders, IIRC.

Perhaps you don't need a preemptive kernel.  For 2.2.x, there are
patches which add additional scheduling points to lower average
latency (but I don't know if you get an exact 5ms timing, perhaps with
a kernel module using the real-time clock interrupt).