> > This is a fairly big move, one I don't think any of the major Unices have
> > done.
> The other Unices are at least evenly split, or mostly preemptible.
> Typically, a more complex strategy is used where spinlocks can sleep
> after a few spins. This patch is very conservative in that regard,
> it basically just uses the structure we already have, SMP spinlocks.
I did not know other Unices were (in general) preemptible. Solaris is?
The only one I thought was preemptible was Irix.
Anyhow, you are right about the simplistic approach we take. There are
a few alternatives: mixing mutexes and shorter locks, priority-bearing
semaphores, changing the way the preemption count works, etc.
> > The only reason the patch is not _huge_ is because the Linux
> > kernel is already setup for concurrency of this nature -- it does SMP.
> > I suggest you read
> > http://www.linuxdevices.com/articles/AT4185744181.html
> > http://www.linuxdevices.com/articles/AT5152980814.html
> > http://kpreempt.sourceforge.net
> > and my previous threads on this issue, for more informaiton.
> Hmm, how did you read those and come to such a different conclusion?
What different conclusion? What are you even arguing with me about?
Do you think I am against a preemptible kernel? I _posted_ the damn
patch, of course I am not.
I probably agree with whatever you are thinking.
-- Robert M. Love rml at ufl.edu rml at tech9.net
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