Re: hyperthreading

Mladen Gogala <mgogala_at_adelphia.net> wrote in message news:<pan.2004.01.11.06.15.24.204294_at_adelphia.net>...
> On Fri, 09 Jan 2004 14:42:18 -0800, Joel Garry wrote:
>
> >
> > Now all we need is the 2.6 kernel and Oracle properly threaded to use
> > it.
>
> You would like to replace fork-ed processes with threads?
> Why would that be good? The problem is that threads all share
> the same address space while processes have their own address
> spaces. Shared are only certain critical sections which are
> known as "Shared Global Area". I should also add that the threads
> implementations are OS specific (ranging from light-weight processes
> to user mode thread which are actually serially executed in such a
> way that user thinks that threads are run concurrently. The latter are
> know as "green threads".). Using threads instead of fork & SYSV IPC would
> probably have disastrous consequences for performance. It would turn even
> the best Unix systems into an Xtreme Perversion, XP for short.

I was hoping there would be coding that could be done on the Oracle side to take advantage of hyperthreading. The idea is to use hardware capabilities to improve things (I would speculate that such things as SGA buffer maintenance could benefit from this). If you get 30% improvement by using these capabilities, after the expense of a 50% decrease simply moving away from forks, that would indeed be silly. But if we're going to compete with other products optimized to use perversion, we must look at how everything works together and not be religious about ... whatever.

jg

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