OpenCXD: An Open Real-Device-Guided Hybrid Evaluation Framework for CXL-SSDs
🤖 AI Summary
Existing CXL-SSD studies are constrained by the absence of hardware natively supporting the CXL.mem protocol, hindering accurate modeling of firmware behavior and underlying storage dynamics. To address this, we propose the first hybrid evaluation framework that integrates a cycle-accurate CXL.mem host-side simulator with a physical OpenSSD device executing production firmware—enabling co-execution of controller logic and real storage hardware. This framework pioneers the incorporation of actual firmware execution into CXL-SSD evaluation, overcoming key limitations of pure simulation in modeling firmware interactions, media scheduling, and device-level phenomena. Experimental results uncover critical performance bottlenecks previously invisible to conventional approaches—including firmware-path latency and CXL link utilization mismatch—thereby establishing a reproducible, high-fidelity empirical foundation for co-designing CXL-SSD architectures and firmware.
Application Category
📝 Abstract
The advent of Compute Express Link (CXL) enables SSDs to participate in the memory hierarchy as large-capacity, byte-addressable memory devices. These CXL-enabled SSDs (CXL-SSDs) offer a promising new tier between DRAM and traditional storage, combining NAND flash density with memory-like access semantics. However, evaluating the performance of CXL-SSDs remains difficult due to the lack of hardware that natively supports the CXL.mem protocol on SSDs. As a result, most prior work relies on hybrid simulators combining CPU models augmented with CXL.mem semantics and SSD simulators that approximate internal flash behaviors. While effective for early-stage exploration, this approach cannot faithfully model firmware-level interactions and low-level storage dynamics critical to CXL-SSD performance. In this paper, we present OpenCXD, a real-device-guided hybrid evaluation framework that bridges the gap between simulation and hardware. OpenCXD integrates a cycle-accurate CXL.mem simulator on the host side with a physical OpenSSD platform running real firmware. This enables in-situ firmware execution triggered by simulated memory requests. Through these contributions, OpenCXD reflects device-level phenomena unobservable in simulation-only setups, providing critical insights for future firmware design tailored to CXL-SSDs.
Problem
Research questions and friction points this paper is trying to address.
Evaluating CXL-SSD performance lacks native hardware support
Hybrid simulators miss firmware-level and low-level storage dynamics
Bridging gap between simulation and hardware for CXL-SSD evaluation
Innovation
Methods, ideas, or system contributions that make the work stand out.
Hybrid framework combining simulation and real hardware
Cycle-accurate CXL.mem simulator with physical OpenSSD
In-situ firmware execution for realistic performance insights
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