|
Multiprocessing capability is a main design goal of the PowerUP product
line and the PowerUP system software. We are convinced, that every advanced
and progressive OS development has to incorporate multiprocessing, since
this is a main basic for the expandibility of future systems. This was the
reason to orient our development mainly on multiprocessing. We consider
an inadequate or even missing support of multiprocessing as a major restriction.
Already the current PowerUP boards are using both CPUs featuring parallel
multiprocessing. Although both CPUs dynamically share the same bus, a sufficient
memory access is guaranteed for both, because the peak memory bandwith is
appx 200 MB/sec. Dynamic bus allocation means, that to both CPUs alternatingly
four burst cycles access are granted if they request continous memory access;
if one CPU requires less or even no memory access, the other CPU gets more
bus cycles granted. Logic analyzer traces show, that both CPUs even on heavy
load, very often release the bus, which enables other bus masters like SCSI
DMA or additional CPUs to use the bus. A Mandelbrot calculation or a MPEG
decode for example requires the PPC to read a certain amount of data using
burst accesses, and subsequently during the calculation the bus is released.
During this period the bus is available to the 68k CPU, which can do other
tasks such as OS functions, preparing data for the next PPC task or interprete
data returned from the PPC. By using structured programming styles like
documented in our guidelines, the application
can take optimal advantage of both CPUs performance and the available memory
bandwith with full support of our hardware.
To get most out of a multiprocessing hardware, the software needs to
be adapted to the hardware. By the features of our PowerUP system software
this adaption is included as much as possible in the system libraries and
requires only minor changes to current application designs. By use of our
multiprocessing prepared message system it is possible to incorporate not
only additional PPC processors but also special GL-3D CPUs or DSPs or even
have a cluster of networked systems working simultaneously on a certain
task. Applications that use our PowerUP system software are prepared to
use these possibilities without or at least only minor changes. This can
be the base for creative development of hardware and software and we hope
that - even in these times of mass computing and nearly monopilistic standardization
of the technologies - this opens possibilities for creative developers to
built up fascinazing solutions and products for and with the Amiga far beyond
todays limitations.
We consider the sometimes arousing proposal that future Amigas will remain
single processor systems as not progressive and leading only to intermediate
solutions. All in all it is anyways just speculation. Even if the basic
machine will stay a single CPU system, there will be third party vendors
offering multi processor extensions for the Amiga.
|
