IDF 2005: Intel reveals details of new CPU design - tech
(hx) 04:57 PM CEST - Aug,24 2005
- Post a comment As expected, Intel announced at its developer forum
a new processor architecture. Basically, the hardware designers took the
best elements of the Pentium M "Banias" architecture - such as power saving
features - as well as some functionalities of the current Netburst model of the
Pentium 4 - such as the quad-pumped bus - to create the new architecture that
will appear in desktop, mobile and server processors in the second half of 2006.
This
dual-core CPU design will support an array of Intel technologies, including
64-bit EM64T compatibility, virtualization, enhanced security, and active
management capabilities. Intel says the new chips will deliver big improvements
in performance per watt, especially compared to its Netburst-based offerings.
At 14 stages, the main pipeline will be a little bit longer than current
Pentium M processors. The cores will be a wider, more parallel design capable of
issuing, executing, and retiring four instructions at once. (Current x86
processors are generally three-issue.) The CPU will, of course, feature
out-of-order instruction execution and will also have deeper buffers than
current Intel processors. These design changes should give the new architecture
significantly more performance per clock, and somewhat consequently, higher
performance per watt.
Unlike Intel's current dual-core CPU designs, which don't really share resources
or communicate with one another except over the front-side bus, this new design
looks to be a much more intentionally multicore design. The on-die L2 cache will
be shared between the two cores, and Intel says the relative bandwidth per core
will be higher than its current chips. L2 cache size is widely scalable to
different sizes for different products. The L1 caches will remain separate and
tied to a specific core, but the CPU will be able to transfer data directly from
one core's L1 cache to another. Naturally, these CPUs will thus have two cores
on a single die.
The first implementation of the architecture will not include Hyper-Threading, but Intel (somewhat cryptically) says to expect additional threads over time. I don't believe that means HT capability will be built into silicon but not initially made active, because Intel expressly cited transistor budget as a reason for excluding HT.
On the memory front, the new architecture is slated to have the ever-present "improved pre-fetch" of data into cache, and it will also include what Intel calls "memory disambiguation." That sounds an awful lot like a NUMA arrangement similar to what's found on AMD's Opteron, but I don't believe it is. This feature seems to be related to a speculative load capability instead..
related links:
Pentium
cores present and future pictured @ TechReport,
Intel's New Architecture Details Revealed @ AnandTech
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