Messages in this thread | | | Date | Mon, 6 Mar 2000 11:29:47 +0200 | From | Tuukka Toivonen <> | Subject | Re: Linux kernerl preemptive ?? |
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On Sat, 4 Mar 2000, Alexey Zhuravlev wrote: > Tuukka Toivonen wrote: > > Some people (mainly Larry McVoy) have proposed that this shouldn't be > > done. He has proposed another way how scalability should be achieved. But > > since you didn't ask that, I stop my story here. > very interesting. Can you continue from this point?
The best answer would be an url to the larry's postscript documents, which describe this. He has posted the urls here earlier, but I don't remember it anymore. Someone else to repost it? Or try searching archives for "larry mcvoy labs" or something =)
I have once read his papers and followed discussion here, but I'm not really qualified to answer. However, I'll do my best...
The main idea seems to be to duplicate the kernel data structures in memory. For example, 32-way SMP system might have 8 copies of kernel data, each running as 4-way SMP system. This means that the kernel copy A accessing its own data structures locks only its own data -- kernel copies B, C, ... are not locked and can run at full speed.
This also means that the cache coherency is not necessary between different copies of kernel.
The kernel copies would communicate via shared memory blocks. For example, buffer cache might be shared.
As I have understood, Larry has mainly talked this kind of operating system on dedicated hardware, like SGI Origin 2000. My own opinion is (please correct me if I'm wrong) is that it might help on Intel-style (ie. shared bus) too, but the problem with Intel style hardware is that the bus saturates easily. Unlike on Origin 2000, which doesn't have a shared bus but a kind of switch between nodes, of which each have several CPUs.
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