Adaptive track scheduling to optimize concurrency and vectorization in GeantV

Journal Article · Fri May 22 00:00:00 EDT 2015 · Journal of Physics. Conference Series

DOI:https://doi.org/10.1088/1742-6596/608/1/012003· OSTI ID:1332185

Apostolakis, J. ^[1]; Bandieramonte, M. ^[2]; Bitzes, G. ^[3]; Brun, R. ^[1]; Canal, P. ^[4]; Carminati, F. ^[1]; Licht, J. C. De Fine ^[5]; Duhem, L. ^[6]; Elvira, V. D. ^[4]; Gheata, A. ^[1]; Jun, S. Y. ^[4]; Lima, G. ^[4]; Novak, M. ^[1]; Sehgal, R. ^[7]; Shadura, O. ^[8]; Wenzel, S. ^[1]

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1. European Organization for Nuclear Research (CERN), Geneva (Switzerland)
2. Univ. of Catania and INAF, Catania (Italy)
3. Univ. of Athens (Greece)
4. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
5. Univ. of Copenhagen (Denmark)
6. Intel Corp., Santa Clara, CA (United States)
7. Bhabha Atomic Research Center (BARC), Mumbai (India)
8. National Technical Univ. of Ukraine, "Kyiv" Politechnic Institute (Ukraine)

The GeantV project is focused on the R&D of new particle transport techniques to maximize parallelism on multiple levels, profiting from the use of both SIMD instructions and co-processors for the CPU-intensive calculations specific to this type of applications. In our approach, vectors of tracks belonging to multiple events and matching different locality criteria must be gathered and dispatched to algorithms having vector signatures. While the transport propagates tracks and changes their individual states, data locality becomes harder to maintain. The scheduling policy has to be changed to maintain efficient vectors while keeping an optimal level of concurrency. The model has complex dynamics requiring tuning the thresholds to switch between the normal regime and special modes, i.e. prioritizing events to allow flushing memory, adding new events in the transport pipeline to boost locality, dynamically adjusting the particle vector size or switching between vector to single track mode when vectorization causes only overhead. Lastly, this work requires a comprehensive study for optimizing these parameters to make the behaviour of the scheduler self-adapting, presenting here its initial results.

• Research Organization: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: AC02-07CH11359
• OSTI ID: 1332185
• Report Number(s): FERMILAB-CONF-14-590-CD; 1372955
• Journal Information: Journal of Physics. Conference Series, Vol. 608, Issue 1; ISSN 1742-6588
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS