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Extending statistical cache models to support detailed pipeline simulators
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. (UART)
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. (UART)
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. (UART)
2014 (English)In: 2014 IEEE International Symposium On Performance Analysis Of Systems And Software (Ispass), IEEE Computer Society, 2014, p. 86-95Conference paper, Published paper (Refereed)
Abstract [en]

Simulators are widely used in computer architecture research. While detailed cycle-accurate simulations provide useful insights, studies using modern workloads typically require days or weeks. Evaluating many design points, only exacerbates the simulation overhead. Recent works propose methods with good accuracy that reduce the simulated overhead either by sampling the execution (e.g., SMARTS and SimPoint) or by using fast analytical models of the simulated designs (e.g., Interval Simulation). While these techniques reduce significantly the simulation overhead, modeling processor components with large state, such as the last-level cache, requires costly simulation to warm them up. Statistical simulation methods, such as SMARTS, report that the warm-up overhead accounts for 99% of the simulation overhead, while only 1% of the time is spent simulating the target design. This paper proposes WarmSim, a method that eliminates the need to warm up the cache. WarmSim builds on top of a statistical cache modeling technique and extends it to model accurately not only the miss ratio but also the outcome of every cache request. WarmSim uses as input, an application's memory reuse information which is hardware independent. Therefore, different cache configurations can be simulated using the same input data. We demonstrate that this approach can be used to estimate the CPI of the SPEC CPU2006 benchmarks with an average error of 1.77%, reducing the overhead compared to a simulation with a 10M instruction warm-up by a factor of 50x.

Place, publisher, year, edition, pages
IEEE Computer Society, 2014. p. 86-95
Series
IEEE International Symposium on Performance Analysis of Systems and Software-ISPASS
National Category
Computer Sciences
Identifiers
URN: urn:nbn:se:uu:diva-224221DOI: 10.1109/ISPASS.2014.6844464ISI: 000364102000010ISBN: 978-1-4799-3604-5 (print)OAI: oai:DiVA.org:uu-224221DiVA, id: diva2:715851
Conference
ISPASS 2014, March 23-25, Monterey, CA
Projects
UPMARCAvailable from: 2014-05-06 Created: 2014-05-06 Last updated: 2018-12-14Bibliographically approved
In thesis
1. Efficient Memory Modeling During Simulation and Native Execution
Open this publication in new window or tab >>Efficient Memory Modeling During Simulation and Native Execution
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Application performance on computer processors depends on a number of complex architectural and microarchitectural design decisions. Consequently, computer architects rely on performance modeling to improve future processors without building prototypes. This thesis focuses on performance modeling and proposes methods that quantify the impact of the memory system on application performance.

Detailed architectural simulation, a common approach to performance modeling, can be five orders of magnitude slower than execution on the actual processor. At this rate, simulating realistic workloads requires years of CPU time. Prior research uses sampling to speed up simulation. Using sampled simulation, only a number of small but representative portions of the workload are evaluated in detail. To fully exploit the speed potential of sampled simulation, the simulation method has to efficiently reconstruct the architectural and microarchitectural state prior to the simulation samples. Practical approaches to sampled simulation use either functional simulation at the expense of performance or checkpoints at the expense of flexibility. This thesis proposes three approaches that use statistical cache modeling to efficiently address the problem of cache warm up and speed up sampled simulation, without compromising flexibility. The statistical cache model uses sparse memory reuse information obtained with native techniques to model the performance of the cache. The proposed sampled simulation framework evaluates workloads 150 times faster than approaches that use functional simulation to warm up the cache.

Other approaches to performance modeling use analytical models based on data obtained from execution on native hardware. These native techniques allow for better understanding of the performance bottlenecks on existing hardware. Efficient resource utilization in modern multicore processors is necessary to exploit their peak performance. This thesis proposes native methods that characterize shared resource utilization in modern multicores. These methods quantify the impact of cache sharing and off-chip memory sharing on overall application performance. Additionally, they can quantify scalability bottlenecks for data-parallel, symmetric workloads.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2019. p. 73
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1756
Keywords
performance analysis, cache performance, multicore performance, memory system, memory bandwidth, memory contention, performance prediction, multi-threading, multiprocessing systems, program diagnostics, commodity multicores, multithreaded program resource requirements, performance counters, scalability bottleneck, scalability improvement
National Category
Computer Systems
Research subject
Computer Science
Identifiers
urn:nbn:se:uu:diva-369490 (URN)978-91-513-0538-7 (ISBN)
Public defence
2019-02-15, Sal VIII, Universitetshuset, Biskopsgatan 3, Uppsala, 09:15 (English)
Opponent
Supervisors
Projects
UPMARC
Available from: 2019-01-23 Created: 2018-12-14 Last updated: 2019-12-02

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Nikoleris, NikosEklöv, DavidHagersten, Erik

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