Sorry to put a dampner on the whole thing, but does anyone have any more
ideas on the original problem?
Original problem: Can I specify which processes run on which CPUs in
Linux?
You should get the performance you need from out of the box scheduling. While
it seems nice to be able to say "I've got 4 processors, and I've got 4 jobs
that each need 90% CPU and I want to make sure that process 1 runs on
processor A ..." this should all be looked after for you by the
scheduling algorithm and you shouldn't need such fine grained control
over what runs where. Keep in mind the general aims of scheduling: it
attempts to give all proceses and users a fair use of
system resources, you want to be very sure of what you're doing if you
think it would be a good idea to go against that policy. You use 'nice' values
for those processes that are more important than others. Real Time
processes needs different scheduling because you have to guarentee you
don't lose your time slice, if you web search on "Real Time Linux"
you should find some material about this, I started reading a thesis
about this subject once but found it heavy going- I think some
versions of Unix had a nice value for real-time processes but don't
quote me.
There's some option to ps that should say which process is running on
which processor but I think it only ever showed one or two processes
that were actively running when the ps was taken, maybe "top" tells
you this info as well.
There's a general perception (or FUD?) in the Linux world that "Linux does
not scale well beyond 4 processors" whatever that means- you should
research this statement too as it might give you a few clues- I doubt
however that the ability to choose which processes run on which
processors is important to this question.
Finally the book "UNIX Systems for Modern Architectures: Symmetric
Multiprocesssing and Caching for Kernel Programmers" by Kurt Schimmel
sounds like it addresses SMP kernel issues and might be handy,
although you should be able to find lots of free stuff on the web. If
you do find some good stuff that answers your question, write up a
summary and post it to the list.
Good luck,
Stuart.
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