A Case for Speculative Address Translation with Rapid Validation for GPUs
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Bibliographic record
Abstract
A unified address space is vital for heterogeneous systems as it enables efficient data sharing between CPUs and GPUs. However, GPU address translation faces challenges due to high TLB pressure, particularly with irregular and memory-intensive applications. Compared to an ideal scenario, we observe that address translation overheads cause a slowdown of up to 34.5% in modern heterogeneous systems. This paper introduces Avatar, a novel framework to accelerate address translation in GPUs. Avatar comprises two key components: Contiguity-Aware Speculative Translation (CAST) and In-Cache Validation (CAVA) mechanisms. Avatar identifies the potential for predicting virtual-to-physical address mapping by monitoring contiguous pages that lie in both virtual and physical address spaces. Leveraging this insight, CAST speculatively translates virtual addresses into physical addresses. This speculative address translation enables immediate data fetching into GPUs while addressing translation occurs in the background, reducing TLB-miss overhead. Unfortunately, modern GPUs lack support for speculative execution, which limits CAST's performance gain. Data fetched from speculated physical addresses is unusable until validation. CAVA addresses this limitation by quickly validating speculated physical addresses. To this end, CAVA embeds page mapping information into each 32B sector of 128B cache lines. Thus, CAVA enables fetching a sector block from memory for a speculated address and rapidly validating the speculative translation using the embedded mapping information. Our experiments show that Avatar achieves a 90.3% (high) speculation accuracy and improves GPU performance by 37.2% (on average).
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it