Re: RT patch acceptance

[Valdis.Kletnieks@vt.edu]

On Sun, 29 May 2005 09:00:49 MDT, Zwane Mwaikambo said:
> On Sun, 29 May 2005 Valdis.Kletnieks@vt.edu wrote:

> > I'd be wildly surprised if media apps *were* commonplace on an operating
> > system that didn't supply the needed scheduling infrastructure.
> > 
> > That's as straw-man as commenting that applications that used more than 16
> > processors weren't commonplace on Linux before the scalability work that made
> > it feasible to build systems with more than 2 CPUs....
> 
> I'm not talking about Linux (which should be obvious as Linux isn't an 
> RTOS), so it has nothing to do with Linux capabilities. I'm referring to 
> general hard realtime applications and their use of realtime operating 
> systems.

As amply shown by the Ardour and linux-audio crowds, the *MAJOR* thing keeping
realtime apps from spreading further is the lack of usable RT support in CTOS
operating systems.  Yes, you *can* do realtime audio - if you're willing to not
use a common operating system and run some specialized RTOS instead.  This is
frequently a show-stopper for small-time use - if there's an additional $5K
cost to getting and installing an RTOS (quite likely you need a new computer,
or redo the one you have to dual-boot), it may not be a problem for a large
recording studio - but it *is* a problem for a small studio or a home user.
So you end up with "The 150 places that buy 48-channel mixers are using RT,
but the 40,000 people who buy 4/8 channel mixers aren't" - by your standards,
nobody's interested in 48-channel mixing boards either.

So tell me - who was using SMP with large numbers of processors *before* the
Linux kernel?  Hmm.. You could buy an SGI Onyx.  A Sun E10K.  The IBM gear.
And for some odd reason, there wasn't many sites that just weren't doing
SMP - it wasn't that long ago that a 48-CPU Sun was enough to get you on the
Top500 supercomputer list.  Now everybody and their pet llama has a 128-node
system, it seems....

Large-scale SMP, realtime, whatever.  It doesn't matter - you're pointing at it and
saying "But nobody *uses* it" when nobody can afford the technology, when there's
plenty of people lining up and saying "We *would* be using it if it were accessible".

Nobody drives around in Rolls Royces and Bentleys either - and 20 years ago, you
could have used that to say "But nobody drives luxury cars".  That's changed
considerably - you get a company that decides to make a Lexus, with 95% of the
quality at 10% of the price, and you can see a *lot* of them on the road.....

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