Published in Processors

Exclusive details on AMD's Zen

by on13 August 2015


No more shared FPU per two cores

Our well informed industry sources have shared a few more details about the AMD's 2016 Zen cores and not it appears that the architecture won't use the shared FPU like Bulldozer. 

The new Zen uses a SMT Hyperthreading just like Intel. They can process two threads at once with a Hyperthreaded core. AMD has told a special few that they are dropping the "core pair" approach that was a foundation of Bulldozer. This means that there will not be a shared FPU anymore.

Zen will use a scheduling model that is similar to Intel's and it will use competitive hardware and simulation to define any needed scheduling or NUMA changes.

Two cores will still share the L3 cache but not the FPU. This because in 14nm there is enough space for the FPU inside of the Zen core and this approach might be faster.

We mentioned this in late April where we released a few details about the 16 core, 32 thread Zen based processor with Greenland based graphics stream processor. 

Zen will apparently be ISA compatible with Haswell/Broadwell style of compute and the existing software will be compatible without requiring any programming changes.

Zen also focuses on a various compiler optimisation including GCC with target of SPECint v6 based score at common compiler settings and Microsoft Visual studio with target of parity of supported ISA features with Intel.

Benchmarking and performance compiler LLVM targets SPECint v6 rate score at performance compiler settings.

We cannot predict any instruction per clock (IPC improvement) over Intel Skylake, but it helps that Intel replaced Skylake with another 14nm processor in later part of 2016. If Zen makes to the market in 2016 AMD might have a fighting chance to narrow the performance gap between Intel greatest offerings.  

Last modified on 13 August 2015
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