Specifying memory consistency of write buffer multiprocessors
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Write buffering is one of many successful mechanisms that improves the performance and scalability of multiprocessors. However, it leads to more complex memory system behavior, which cannot be described using intuitive consistency models, such as Sequential Consistency. It is crucial to provide programmers with a specification of the exact behavior of such complex memories. This article presents a uniform framework for describing systems at different levels of abstraction and proving their equivalence. The framework is used to derive and prove correct simple specifications in terms of program-level instructions of the sparc total store order and partial store order memories.The framework is also used to examine the sparc relaxed memory order. We show that it is not a memory consistency model that corresponds to any implementation on a multiprocessor that uses write-buffers, even though we suspect that the sparc version 9 specification of relaxed memory order was intended to capture a general write-buffer architecture. The same technique is used to show that Coherence does not correspond to a write-buffer architecture. A corollary, which follows from the relationship between Coherence and Alpha, is that any implementation of Alpha consistency using write-buffers cannot produce all possible Alpha computations. That is, there are some computations that satisfy the Alpha specification but cannot occur in the given write-buffer implementation.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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