A Wi(l)der Core Design
The 'wider' core design marks Zen 5 as a foundational architecture, departing from the 6-wide dispatch utilized since Zen 1. Future iterations of AMD's Zen architectures are expected to capitalize on this broadened core, focusing on maximizing the efficiency and performance gains it offers. As mentioned AMD's Zen 5 architecture introduces broader data pathways, which require adjustments to maintain data flow efficiency. To support these wider pipelines, AMD has upgraded the bandwidth of the L1 and L2 caches. This improvement is vital to prevent slowdowns that could undermine the effectiveness of the expanded pipelines. below a block diagram listing the architectural changes inbetween Zen 4 and Zen 5.
A standout detail of Zen 5 is the 50% increase in the size of the L1 cache, which luckily did not add any extra delay in data access—commonly seen with larger cache sizes. By overcoming this typical hurdle, AMD ensures that the larger cache enhances performance without drawbacks. These advancements in cache size and bandwidth are essential for keeping the processor performing well and efficiently, especially in managing the demands of the wider pipelines. Furthermore, the enhancements in the L1 and L2 caches in Zen 5 boost the processor's ability to handle large volumes of data swiftly. Quite beneficial for tasks that require intensive data processing.
Present in Zen 4, but with Zen 5, AMD has upgraded to a full 512-bit data path, enabling AVX-512 to operate at full speed. This transition reduces the latency of AVX-512 computations from three cycles in Zen 4 to two cycles in Zen 5. Previously, Zen 4 processed 512-bit AVX-512 workloads by splitting them into two 256-bit chunks to prevent significant frequency fluctuations, similar to Intel’s approach. However, Zen 5 eliminates this issue by integrating a complete 512-bit data path. The floating-point (FP) and vector math unit in Zen 5 includes six pipelines with reduced latency for floating-point addition (FADD) instructions, now requiring only two cycles instead of three. Additionally, Zen 5 can handle a greater number of in-flight FP instructions compared to its predecessor. AMD highlights the importance of AVX-512 for artificial intelligence (AI) applications, making these improvements crucial for the company's more all-around AI objectives.
