Sun, 30 Apr 2000 [EMAIL PROTECTED] wrote:
> Sounds like b.s., but we will see.
Well...
"Linux developers have discussed redesigning the scheduler, but changing it to
process real-time requests (...)"
There is SCHED_FIFO and SCHED_RR in the current mainstream kernels. For Linux
2.4 it'll probably turn *hard* real-time - the patches have been available and
working for months, and seems to be going in last thing I heard, but *soft* real
time has been there for "ages".
Also, the statement that there is "no way to prioritize tasks" is bogus, even
without counting the real-time scheduling policies. Further, SCHED_FIFO and
SCHED_RR bypasses the normal timesharing completely, and can thus be seen as a
separate, higher priority scheduling class. Finally, the tasks in this
scheduling class *does have priorities*, just as normal tasks.
The only thing you *can't* do with a standard Linux kernel or even with the
lowlatency patch/2.4 (*) is to preempt the kernel to run a RT task. That's the
actual problem with RT scheduling under Linux, but this isn't mentioned at all
in the text!
I think this looks like an example of classical M$ style FUD. Technical
errors, missing facts, incorrect explanations of terms, "we invented this!" -
it's all there. This is the kind of stuff that makes me look for more serious
alternatives, if I should need a proprietary solution.
> On Sat, Apr 29, 2000 at 01:31:05PM +0200, Tomasz Motylewski wrote:
> >
> > Does anynone know something about http://www.wideopen.com/story/838.html
> >
> > They have completely neglected to mention already existing systems.
(*) Ingo did code a patch that enables/disables preemption when doing lengthy
but "safe" operations, but Linus wasn't exactly happy about it... Linus' idea is
that if anything takes long enough to cause more than the sub ms jitter we can
accept for multimedia RT, it's the offending kernel code that should be fixed -
not the symptom.
David Olofson
Programmer
Reologica Instruments AB
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