According to the keynote speakers at Microprocessor Forum
2003, microprocessor architecture, and the microprocessor
itself, is dead—or, at least, no longer evolving. This
would be very troubling news if it were true, but there's
no need to worry.
When Sun CTO Greg Papadopoulos said "microprocessors are
dead," he meant that discrete processors of the conventional
type—one CPU per chip—are no longer the best solution
for some high-end systems.
In saying that processor architectures have stopped evolving,
AMD CTO Fred Weber was actually pointing out that instruction-set
architecture (ISA) has become almost irrelevant to the costs
and capabilities of modern microprocessors. In his view, there
is no need for a new ISA such as Intel's IA-64; the PC and
server markets should consolidate on the AMD64 ISA instead.
AMD would naturally benefit from such an outcome, but Weber
offered strong quantitative arguments why this should happen.
As Weber pointed out, the influence of ISA on design effort,
transistor count, clock speed, and power consumption in today's
PC processors is almost negligible. Weber left room for future
work in application-specific instruction-set extensions such
as MMX, SSE, and 3DNow, but showed that the AMD64 ISA is a
good foundation for future processor development. Microarchitecture,
Weber said, is where the real action will be—and we agree
with that.
It is not apparent to me that Intel has proven the need
for IA-64, or that all of today's server customers could ever
be switched over to Itanium processors. During lunch at MPF,
I heard an anecdote from an engineer at a major OEM currently
building Xeon servers for its proprietary online transaction-processing
software. This engineer said that his company tested and rejected
Itanium because the x86-specific optimizations in its software
imposed terrible performance penalties on a simple IA-64 translation.
Itanium gave them one-fifth the performance at four times
the cost. No doubt this result could be drastically improved
with some effort, but why bother, he asked?
It would be difficult for Intel to license AMD64, but for
political rather than technical or financial reasons. Intel
could easily make the necessary changes to the Pentium 4 pipeline,
and it's reasonable to assume that Intel's manufacturing and
marketing strengths would preserve its market share. The trouble
is that Intel originated the x86 architecture and was responsible
for all the major improvements to the ISA over the years.
Intel even developed its own 64-bit extensions—the Yamhill
technology we believe was designed into the forthcoming Prescott
processor—though they may never see the light of day.
AMD64, even under another name, would be a very bitter pill
for Intel to swallow.
However the PC and server markets go, Weber was disregarding
current trends in embedded processors, where ISA changes are
essential to achieving the full potential of new concepts
in parallel processing. It's difficult to imagine AMD64 being
used by extreme-processor startups exploring heterogeneous
multiprocessing and VLIW pipelines.
Similarly, I'm sure there will always be room in the computer
industry for conventional chip-scale microprocessor cores,
no matter what Sun may do with Throughput Computing in server
systems. Simple microprocessors will always be the best answer
for some systems where the application-specific logic is best
developed separately from the CPU core.
In embedded systems, PCs, workstations, and supercomputers,
software that doesn't lend itself to parallel processing will
always be with us, creating permanent markets for the biggest,
fastest cores possible. What we call a "microprocessor" will
surely change in the coming years, but the microprocessor
will outlive us all.
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