An Analysis of User-space Idle State Instructions on x86 Processors
Research output: Contribution to book/Conference proceedings/Anthology/Report › Conference contribution › Contributed › peer-review
Contributors
Abstract
Power consumption has become a limiting factor in all areas of computing. Hence, making the most of the available power budget is paramount. To use the available budget most efficiently, techniques like dynamic voltage and frequency scaling and idle states can be used. This work analyzes the instructions UMWAIT, TPAUSE, and MWAITX on three different systems. We analyze their instruction latencies, power consumptions, and dependencies on core frequencies. To do so, we introduce benchmarks to gather performance and power parameters, which can be used for future software optimizations. Key findings include: The expected sleep duration passed to UMWAIT and TPAUSE can influence the depth of the user idle state. The actual sleep duration of TPAUSE increases stepwise with an increasing expected sleep duration. Requesting a deeper idle state leads to an additional sleep duration, which increases with a lower core frequency. The core frequency influences the instruction latency of TPAUSE, where a low frequency can lead to an irregular performance pattern. The latency of TPAUSE, UMWAIT, and MWAITX is most often higher than requested on the evaluated systems. Core power consumption can be reduced by ∼20% ∼70% compared to the usage of PAUSE. The latency for waking a core in user idle reflects the underlying hardware architecture with tens (desktop architecture with shallow idle states) to hundreds (server architecture with deep idle states) of nanoseconds at nominal frequencies.
Details
| Original language | English |
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| Title of host publication | ICPE 2025 - Proceedings of the 16th ACM/SPEC International Conference on Performance |
| Publisher | Association for Computing Machinery, Inc |
| Pages | 232-239 |
| Number of pages | 8 |
| ISBN (electronic) | 9798400710735 |
| Publication status | Published - 5 May 2025 |
| Peer-reviewed | Yes |
Publication series
| Series | ICPE: ACM/SPEC International Conference on Performance Engineering |
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Conference
| Title | 16th ACM/SPEC International Conference on Performance |
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| Abbreviated title | ICPE 2025 |
| Conference number | 16 |
| Duration | 5 - 9 May 2025 |
| Website | |
| Location | York University |
| City | Toronto |
| Country | Canada |
External IDs
| ORCID | /0000-0001-9601-8683/work/186621393 |
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Keywords
Sustainable Development Goals
ASJC Scopus subject areas
Keywords
- energy efficiency, mwaitx, tpause, umwait, user-space idle states