Managing Memory Tiers with CXL in Virtualized Environments
Talkat 18th USENIX Symposium on Operating Systems Design and Implementation (OSDI '24) · 2024-07-10..07-12
summary
Introduces Intel Flat Memory Mode, a hardware-managed, cacheline-granular CXL tier that acts as a direct-map exclusive cache with zero CPU overhead and huge-page compatibility, evaluated on a preproduction Xeon (Granite Rapids) and an Astera Labs CXL card across 115 cloud workloads; hardware tiering gives near-DRAM performance for >82% of workloads but produces two failure modes — cross-VM contention and intra-VM conflicting access patterns — causing up to 34% slowdowns. Adds Memstrata, a hypervisor allocator using page coloring and an online slowdown estimator (L3 miss-latency proxy) to assign dedicated local DRAM, reducing outlier slowdowns to under ~6%.
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