by Anton Shilov
05/10/2014 | 05:54 PM
Jim Keller, the legendary lead-developer behind K7 and K8 micro-architectures that were breakthroughs for AMD, is now back at AMD. Apparently, not only for the K12 ARMv8-based project, but also for a new high-performance x86 micro-architecture. According to unofficial information, the new micro-architecture will be unveiled sometimes towards late 2015.
While the Bulldozer micro-architecture and its derivatives provide an easy way to scale up the number of cores within a microprocessor, it also has a number of drawbacks that have so far have overshadowed all the advantages that the concept provides. AMD’s current multi-core microprocessors are built according to the so-called CMT [clustered multi-thread] design that [in AMD Bulldozer’s case] involves so-called dual-core “modules”.
Each dual-core module is alike a dual-core processor when it comes to integer power, and to a single-core processor with simultaneous multi-threading (SMT) capability in its floating-point performance (each module has two ALUs, yet, essentially, one FPU [floating point unit]). Since each module shares certain resources between two “cores”, in many cases their efficiency is not high enough.
To make the matters even worse, single-thread performance of AMD Bulldozer-derived architectures is lower compared to Intel’s. As a consequence, in many cases AMD’s eight-core FX-series central processing units are behind in terms of real world performance when compared to Intel’s quad-core chips that have the same number of floating point units (FPUs) which are more efficient compared to AMD’s FPUs.
Based on the unofficial information, everything is going to change in the next micro-architecture that is in development by AMD. Development of a new high-performance general-purpose x86 core from Advanced Micro Devices is currently in development headed by Jim Keller, according to Expreview web-site.
Not a lot of details about the new micro-architecture are known at present. What is recognized for sure is that it will drop CMT in favour of some kind of SMT (something akin to Intel’s HyperThreading) technology to improve performance in both single-threaded and multi-threaded cases.
Partly because the head of the development – Jim Killer – is basically a legend, it is hard to predict any ideas that his team might come up to during the designing process. Quite naturally, we are unlikely to see many details about the new x86 core by AMD before it actually decides to make a disclosure.
Jim Keller at an AMD event
All the latest instruction-set extensions to the x86 architecture will probably be supported by the new micro-architecture. Expect AVX 3.2 512-bit extensions among many others.
The new micro-architecture is reportedly set to be detailed by the end of 2015. At present it is unknown whether AMD will just reveal all the details or even introduce new actual products.
The all-new micro-architecture by AMD is set to emerge only in late 2015. But before that we will probably see the last and final play of the Bulldozer in the form of the Excavator cores that are projected to be present in the 2014 APUs code-named Carrizo and Toronto.
While the Excavator will definitely show what the Bulldozer micro-architecture is capable of, it will unlikely deliver performance that the public wants from it to compete against Intel’s Core i7-series microprocessors.
What is, perhaps, more important is that one of AMD’s official document detailed a sixteen-core AMD Bulldozer-derived processor. If the company pursues this opportunity an goes for a 16-core chip featuring Steamroller or Excavator cores, its new chips based on the new micro-architecture will only be available in 2016 or even 2017.
While nothing is clear now, a good news is that AMD has not given up high-end microprocessors for servers and clients, the Opteron and the FX-series.
AMD did not comment on the news-story.