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Software prefetching for indirect memory accesses: A microarchitectural perspective

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Jones, TM 


jats:pMany modern data processing and HPC workloads are heavily memory-latency bound. A tempting proposition to solve this is software prefetching, where special non-blocking loads are used to bring data into the cache hierarchy just before being required. However, these are difficult to insert to effectively improve performance, and techniques for automatic insertion are currently limited.</jats:p> jats:pThis article develops a novel compiler pass to automatically generate software prefetches for indirect memory accesses, a special class of irregular memory accesses often seen in high-performance workloads. We evaluate this across a wide set of systems, all of which gain benefit from the technique. We then evaluate the extent to which good prefetch instructions are architecture dependent and the class of programs that are particularly amenable. Across a set of memory-bound benchmarks, our automated pass achieves average speedups of 1.3× for an Intel Haswell processor, 1.1× for both an ARM Cortex-A57 and Qualcomm Kryo, 1.2× for a Cortex-72 and an Intel Kaby Lake, and 1.35× for an Intel Xeon Phi Knight’s Landing, each of which is an out-of-order core, and performance improvements of 2.1× and 2.7× for the in-order ARM Cortex-A53 and first generation Intel Xeon Phi.</jats:p>



Software Prefetching, Compiler Analysis, Microarchitecture

Journal Title

ACM Transactions on Computer Systems

Conference Name

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Volume Title



Association for Computing Machinery (ACM)
EPSRC (1510365)
Engineering and Physical Sciences Research Council (EP/K026399/1)
Engineering and Physical Sciences Research Council (EP/M506485/1)
EPSRC [EP/K026399/1, EP/M506485/1], ARM Ltd.