Xputers: FQA (3): |
Xputers:
FQA (1)
Xputers:
FQA (2)
Xputers and Hardware/Software Co-Design
Xputers and Custom Computing Machines
Xputers and Application-specific Processors
Xputers and ASIPs
Xputer Applications
The Xputer: more than just a General Purpose Accelerator
Hardware/Software Co-Design [1] has the goal to optimize the hardware/software trade-off in Partitioning an application problem into a software part (to run on the host) and an add-on accelerator hardware part. Researchers complaint [2] that a general model is missing, which brings the very wide variety of architectures under a common umbrella. The Xputer paradigm has the potential to be such a general model of hardware/software co-design (see here).
The design of custom computing machines [3]
[4] is similar to hardware/software
co-design.
The main difference is the use of fied-rgramabe ccelerators, whereas
hardware/software
co-design prefers hardwired add-om accelerators. Also here the Xputer
paradigm
has the potential to be a general model of hardware/software co-design
(see here),
which bridges the many gaps between the very wide variety of
architectures.
For implementing Application-specific accelerators a hardware
experts
are needed, even for FPGA-based custom somputing machines. Compilers
accepting
programming languages are not available for synthesis, so that these
ommercially
available platforms are far from the dream of software-only
implementation
of accelerators. The ASIP approach redesigns everything (see next
section),
even compiler and operating system are application-specific - a huge
effort,
as long as a very powerful repertory of generators is not available.
Custom
computing machines [3] [4]
are a tinker toy approach not permitting a systematic compilation
environment.
What we need are general purpose accelerators - technology platforms
suitable
for being supported by a novel class of application development tools.
compilation techniques. The key issue on the way to implementation [5]
of accelerators are general purpose compilation techniques instead of
specialized
compilers. We believe, that Xputer-based platform architectures are the
best basis of general purpose compilers for software-only accelerator
implementation.
ASIPs (Application-specific Instruction Set Processors [6]
[7] ) are developped by experimenting with
alternative
processor architectures for particular application samples. Their
alternative
perfornce data are derived by profiling from simulation. Each
alternative
requires a complete processor design, so that there is no compatibility
to existing software of any kind. That's why an ASIP development
environment
should have a bunch of generators like an architecture generator, a
compiler
generator, operating system generator, and a simulator generator. Also
see: Application-specific
Processors and Xputers
Xputers provide high speed-up factors for all applications with
halfways
or fully regular data depencencies, such as in DSP, image processing,
most
scientific applications and many others. For more details see section FQA
on Xputers.
The Xputer may also be used in stand-alone mode. E. g. this makes
sense
in embedded systems and in many other eapplication environments with
high
cost/performance trade-off requirements. Xputers are used as central
units,
the CPUs. This means an accelerator without a host: really a full
paradigm
switch. Also see software-only
accelerators.
The usual add-one hardware provides speed-up by software to hardware migration. In addition to his Xputers provide further speed-up by runtime to compile time migration (RT2CT migration). This is shown by comparative overhead analysis. An example is comples address computation (see fig. 26), which ona vonNeumann implementation has to be carried out at run time, whereas on an Xputer this may be done by compiling reconfiguration code to be downloaded into a data sequencer. In a grid-based design rule check implementation, for example, this has contributed one and half order of magnitude to speed-up (see fig. 26).
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