Re: Interesting scheduling times
Richard Gooch (rgooch@atnf.csiro.au)
Fri, 18 Sep 1998 19:30:05 +1000
Larry McVoy writes:
> Richard Gooch <rgooch@atnf.csiro.au>:
> : A good RT system would allow you to put it all on one computer and
> : data would not need to be shipped around (you'd use threads or
> : SHM). However, on such a system you will have a considerable number of
> : (low priority) user processes sitting on the run queue (the latest
> : generation of data reduction software is very modular and has lots of
> : processes doing different parts of the work). A dozen processes is not
> : unreasonable.
>
> A dozen CPU bound processes? You've seen this? Or you think it would
> happen? In every system like this that I've seen (and I've seen a bunch),
> people eventually weed it down to a CPU bound process/CPU, maybe two.
> The throughput of the system slows down otherwise. This is /especially/
> true on RT applications - any inefficiency can't be tolerated.
I can't verify right now, because that observing programme isn't
running now. But those systems do get busy.
And I'm not talking about RT applications with lots of processes, I'm
talking about non-RT processes with lots of processes.
As I said, the next generation of radio astronomy reduction software
is very modular. Someone running this software on a system is going to
have a fair number of processes on the run queue at least some of the
time. This will slow down the scheduling of RT processes.
Regards,
Richard....
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