Task Scheduling for Highly Concurrent Analytical and Transactional Main-Memory Workloads
Bibliographic record
Abstract
Task scheduling typically employs a worker thread per hardware context to process a dynamically changing set of tasks. It is an appealing solution to exploit modern multi-core processors, as it eases parallelization and avoids unnecessary context switches and their associated costs. Naively bundling DBMS operations into tasks, however, can result in sub-optimal usage of CPU resources: highly contending transactional workloads involve blocking tasks. Moreover, analytical queries assume they can use all available resources while issuing tasks, resulting in an excessive number of tasks and an unnecessary associated scheduling overhead. In this paper, we show how to overcome these problems and exploit the performance benefits of task scheduling for main-memory DBMS. Firstly, we use application knowledge about blocking tasks to dynamically adapt the number of workers and aid the OS scheduler to saturate CPU resources. In addition, we show that analytical queries should issue a low number of tasks in cases of high concurrency, to avoid excessive synchronization, communication and scheduling costs. To achieve that, we maintain a concurrency hint, reflecting recent CPU availability, that partitionable analytical operations can use as a limit while adjusting their task granularity. We integrate our scheduler into a commercial main-memory column-store, and show that it improves the performance of mixed workloads, by up to 12.5% for analytical queries and 370% for transactional queries.
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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 | 0.001 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".