Lock-Free High-performance Hashing for Persistent Memory via PM-aware Holistic Optimization
Bibliographic record
Abstract
Persistent memory (PM) provides large-scale non-volatile memory (NVM) with DRAM-comparable performance. The non-volatility and other unique characteristics of PM architecture bring new opportunities and challenges for the efficient storage system design. For example, some recent crash-consistent and write-friendly hashing schemes are proposed to provide fast queries for PM systems. However, existing PM hashing indexes suffer from the concurrency bottleneck due to the blocking resizing and expensive lock-based concurrency control for queries. Moreover, the lack of PM awareness and systematical design further increases the query latency. To address the concurrency bottleneck of lock contention in PM hashing, we propose clevel hashing, a lock-free concurrent level hashing scheme that provides non-blocking resizing via background threads and lock-free search/insertion/update/deletion using atomic primitives to enable high concurrency for PM hashing. By exploiting the PM characteristics, we present a holistic approach to building clevel hashing for high throughput and low tail latency via the PM-aware index/allocator co-design. The proposed volatile announcement array with a helping mechanism coordinates lock-free insertions and guarantees a strong consistency model. Our experiments using real-world YCSB workloads on Intel Optane DC PMM show that clevel hashing, respectively, achieves up to 5.7× and 1.6× higher throughput than state-of-the-art P-CLHT and Dash while guaranteeing low tail latency, e.g., 1.9×–7.2× speedup for the p99 latency with the insert-only workload.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".