* Refinement and simplification of Berti using academic simulators: We first developed an improved and simpler version of Berti, extensively tested across numerous industrial workloads using academic simulators. A key outcome was the removal of timestamps from the L1D cache, simplifying its design. The resulting prefetcher, named Berto (Berti Optimized), was also evaluated with our previously developed Store Prefetch Bursts (SPB) technique, which showed that Berti already captured most of its prefetching benefits.
* Implementation of a local delta prefetcher in hardware: The next step was to implement a prefetcher in hardware using Verilog. For this, it was important to understand the cache interface offered to the prefetcher. Some processors offer richer interfaces, while others are more limited. In any case, these interfaces usually provide less information than academic simulators. Therefore, before implementing, we needed to select the target processor to accommodate its interface or extend it if necessary. After discussions with companies and academic partners, we chose the Sargantana core, developed by the Barcelona Supercomputing Center under the European Processor Initiative. However, Sargantana's L1D interface was quite limited, and extending it was not straightforward. Thus, we adapted our prefetcher to their interface instead of extending the interface itself. The resulting prefetcher was named DeltaRegion. It does not use IP for obtaining local deltas but instead uses nearby memory accesses as proxies for local behavior.
* Testing and refinement of the prefetcher in a real processor: After designing and implementing our prefetcher, we tested it on the Sargantana processor and began a process of fine-tuning to improve performance by identifying suboptimal design choices. After this process, our prefetcher outperformed Sargantana's native prefetcher by around 9% when running the typical workloads used by the Barcelona Supercomputing Center to test the Sargantana core.
* Business model analysis: We held meetings with industry partners and conducted a market survey to identify potential customers for our product. There is interest from industry in our prefetcher. The most promising path for technology transfer identified during this process is working together with industry partners to shape our prefetching methodology to their needs and licensing our products to them.
