Re: Oracle ventures into the O/S market.....?
- From: Nuno Souto <dbvision@xxxxxxxxxxxx>
- Date: Wed, 19 Apr 2006 06:10:09 +1000
Kevin Closson wrote,on my timestamp of 19/04/2006 2:47 AM:
Oh boy. Something tells me you haven't had your hands in the
Informix DSA code as much as I have. The threads scheduler in
that database server was anything BUT "simple time-sharing
round-robin threads". It was a brilliant database-smart scheduler
and as long as it ran on a good OS, you very seldon saw more than
5% of your processor cycles lost to kernel mode...and that
even at extremely high IO rates.
I must admit my knowledge of Informix stopped in 86:
didn't bother after that.
Still, if you spend the time scheduling in kernel mode or
database/user mode, it doesn't matter one tick: you
are still scheduling, the only change is the name.
Yeah, I know: context switches and all that. You
still have to have them unless you completely
replace the OS IO layer, in which case your system
stops being a general purpose computing facility and
becomes a database-only machine.
Those were a short-lived fad: no one can afford such
specialized systems anymore and most implementations
just died out. Sybase was an example of one that
survived by converting to all-software instead of
needing a dedicated computer to run. But it's still
the same old problem: if you put everything in user mode,
(or "db mode", semantics here) then it stops being
a general purpose OS.
What is needed is efficient ring architectures,
but those need another two or three years to flush
out properly. And they'll be used first for simulating
VM-like environments with multiple concurrent OSs in
the same multi-core CPU.
--
Cheers
Nuno Souto
in sunny Sydney, Australia
dbvision@xxxxxxxxxxxx
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