HeMem: Scalable Tiered Memory Management for Big Data Applications and Real NVM


  • DRAM + NVM tiered memory

    • NVM: 8x capacity, 2x latency, assymetric read/write bandwidth, high overhead for small accesses

  • Hardware tiered memory

    • Example: Intel Optane Memory mode

      • no OS support needed

      • low overhead

      • no visibility into apps

      • limited to simple management techniques

  • Software tiered memory

    • Insights into applications, support complex policies

    • But

      • Does not scale to NVM capacity (due to page table overheads)

      • No support for asymmetric read / write bandwidth

      • Limited flexibility

  • HeMem design principles

    • Asynchronous memory access sampling with CPU performance counters

      • PEBS memory access sampling

    • Asynchronous memory migration with DMA offload

      • Hot/code classification

      • Mark the pages as WP

      • DMA copy memory in the background

    • Data scalability awareness

    • Focus on asymmetric NVM bandwidth

    • Flexibility

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