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Subject: Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.32-6
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>Disk access - at least on top of a filesystem - is not real-time. But we
>can say it is some other device.
I am not quite sure you should make such a general statement. There are
a number of "real time" processes that access disk drives. Things that
come to mind include:
 - paging for a visual display system (think a high end flight simulator)
 - streaming data acquisition
 - several multimedia applications (video / audio)
The application I mentioned (simulating a real world system that uses
a disk drive) certainly falls within the real time range as well.

You certainly have to manage the application carefully. But with
preallocated (prefer contiguous) files, you can do quite a lot with
a disk in a real time system. The rates may not be as high as needed
for some applications, but the overall concept is certainly valid.

--Mark H Johnson
  <mailto:Mark_H_Johnson@raytheon.com>