Finite-difference time-domain on the cell/B.E. processor
Bibliographic record
Abstract
Finite-Difference Time-Domain (FDTD) is a kernel used to solve problems in electromagnetics applications such as microwave tomography. It is a data-intensive and computation-intensive problem. However, its computation scheme indicates that an architecture with SIMD support has the potential to bring performance improvement over traditional architectures without SIMD support. The Cell Broadband Engine (Cell/B.E.) processor is an implementation of a heterogeneous multicore architecture. It consists of one conventional microprocessor, PowerPC Processor Element (PPE), and eight SIMD co-processor elements, Synergistic Processor Elements (SPEs). One unique feature of an SPE is that it has 128-entry 128-bit uniform registers which support SIMD. Therefore, FDTD may be mapped well on Cell/B.E. processor. However, each SPE can directly access only 256KB local store (LS) both for instructions and data. The size ofLS is much less than what is needed for an accurate simulation of FDTD which requires large number of fine-grained Yee cells. In this paper, we design the algorithm on Cell/B.E. by efficiently using the asynchronous DMA (direct memory access) mechanism available on an SPE transferring data between its LS and the main memory via the high bandwidth bus on-chip EIB (Element Interconnect Bus). The new algorithm was run on an IBM Blade QS20 blades running at 3.2GHz. For a computation domain of 600 x 600 Yee cells, we achieve an overall speedup of 14.14 over AMD Athlon and 7.05 over AMD Opteron at the processor level.
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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 | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.010 | 0.002 |
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".