| From: | Oliver Roberts |
| Date: | 07 Aug 2000 at 14:47:43 |
| Subject: | Re: morphos ;-) |
On 07-Aug-00 11:50:26 BST, Michael.Merkel wrote:
>> The "Blackbox" emulation was meant for future PPC-only systems
>> to emulate the missing 68k CPU. But those systems never appeared.
> and why not going the "morphos way" by simply disabling the 68k processor
> with the ability to let ppc native programs run at full speed without
> those context switches? if i understand it right only this would give the
> possibility to have a really fast system.
This appears to be a common mis-conception, brought on by the MorphOS
hype machine, I guess :) Until MorphOS contains a totally 68k free
rendition of AmigaOS, MorphOS PPC apps will still not be able to run at
"full" speed.
Why? Well, with WarpOS (and PowerUp) 68k code is obviously run on the 68k,
which obviously involves context-switches, although 68k code can also be
run asynchronously (e.g. a PPC program can be running some code on the 68k
while running code on the PPC, simultaneously - my WarpJPEG and PNG
datatypes maximise this). With MorphOS, PPC apps will still have to use
68k code (e.g. for disk/io) and although this is perhaps not as much as
the overhead associated with a dual-cpu system context-switch, there is
overhead involved and, of course, the emulated 68k code will be slow
(especially for users who are used to using a 68060). And, of course,
apps that utilized the dual-cpu setup before, will not be as fast in
MorphOS because everything is running on the PPC.
Really, the main reason the 68k cpu is disabled in MorphOS is to remove
the overhead required in keeping the 68k and PPC caches synchronised -
MorphOS doesn't have that overhead, but things still get bogged down
because there's still a lot of 68k code in the OS, and MorphOS has to
emulate that on the PPC (which slows down apps which mainly use the PPC -
like the Distributed.net RC5 clients, for example).
As I mentioned, 68060 users will probably notice the difference most,
since the 68k emulation is not capable of the same speed. True, the
native PPC apps will be fast, but what about all the existing software
that is 68k only? And there's also the fact, that all the 68k cpu power
is being wasted. Why settle for the PPC only, when you can have a system
which uses 68k and PPC processors side-by-side? As an example, you
can play mp3s on the PPC, and all your 68k software will still run at
full speed. With MorphOS, playing mp3s will slow everything down.
MorphOS has it's advantages, but it's disadvantages currently outweigh
those, IMHO. That's just my take on the situation. Anyone, please do
correct me if you think I'm wrong :)