Håkon Kvale Stensland

Associate Professor - Networks and Distributed Systems

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Email haakonks@ifi.uio.no

Mobile phone +47 41317406

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Visiting address Kristian Augusts gate 23 0164 Oslo

Postal address Postboks 1080 Blindern 0316 Oslo

Other affiliations Institutt for pedagogikk (Student)

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Senior Research Scientist at Simula Research Laboratory
Teaching IN5050 and IN1020 at the Department of Informatics, University of Oslo

Background

Håkon Kvale Stensland is a senior research scientist at the HPC Department at Simula Research Laboratory. He received his doctoral degree (Ph.D.) in 2015 from the Department of Informatics, University of Oslo. Håkon’s research interests are within the field of distributed processing, and heterogeneous processing architectures. He is also interested in the state of the art in heterogeneous multi-core processors.

Mirmotahari, Omid; Islam, Md Rifat Naim; Berg, Yngvar; Foss, Camilla & Stensland, Håkon Kvale (2023). Spillifisering for økt engasjement, fleksibilitet og alternativt læringsløp. NIKT: Norsk IKT-konferanse for forskning og utdanning. ISSN 1892-0713.
Elmokashfi, Ahmed Mustafa Abdalla; Sundnes, Joakim; Kvalbein, Amund; Naumova, Valeriya; Reinemo, Sven-Arne & Florvaag, Per Magne [Show all 8 contributors for this article] (2021). Nationwide rollout reveals efficacy of epidemic control through digital contact tracing. Nature Communications. ISSN 2041-1723. 12, p. 1–8. doi: 10.1038/s41467-021-26144-8. Full text in Research Archive Show summary
Fuelled by epidemiological studies of SARS-CoV-2, contact tracing by mobile phones has been put to use in many countries. Over a year into the pandemic, we lack conclusive evidence on its effectiveness. To address this gap, we used a unique real world contact data set, collected during the rollout of the first Norwegian contact tracing app in the Spring of 2020. Our dataset involves millions of contacts between 12.5% of the adult population, which enabled us to measure the real-world app performance. The technological tracing efficacy was measured at 80%, and we estimated that at least 11.0% of the discovered close contacts could not have been identified by manual contact tracing. Our results also indicated that digital contact tracing can flag individuals with excessive contacts, which can help contain superspreading related outbreaks. The overall effectiveness of digital tracing depends strongly on app uptake, but significant impact can be achieved for moderate uptake numbers. Used as a supplement to manual tracing and other measures, digital tracing can be instrumental in controlling the pandemic. Our findings can thus help informing public health policies in the coming months.
Rongved, Olav Andre Nergård; Hicks, Steven; Thambawita, Vajira L B; Stensland, Håkon Kvale; Zouganeli, Evi & Johansen, Dag [Show all 9 contributors for this article] (2021). Using 3D Convolutional Neural Networks for Real-time Detection of Soccer Events. International Journal of Semantic Computing (IJSC). ISSN 1793-351X. doi: 10.1142/S1793351X2140002X. Full text in Research Archive
Markussen, Jonas Sæther; Kristiansen, Lars Bjørlykke; Halvorsen, Pål; Kielland-Gyrud, Halvor; Stensland, Håkon Kvale & Griwodz, Carsten (2021). SmartIO: Zero-overhead Device Sharing through PCIe Networking. ACM Transactions on Computer Systems. ISSN 0734-2071. 38(1-2), p. 1–78. doi: 10.1145/3462545. Full text in Research Archive Show summary
The large variety of compute-heavy and data-driven applications accelerate the need for a distributed I/O solution that enables cost-effective scaling of resources between networked hosts. For example, in a cluster system, different machines may have various devices available at different times, but moving workloads to remote units over the network is often costly and introduces large overheads compared to accessing local resources. To facilitate I/O disaggregation and device sharing among hosts connected using Peripheral Component Interconnect Express (PCIe) non-transparent bridges, we present SmartIO. NVMes, GPUs, network adapters, or any other standard PCIe device may be borrowed and accessed directly, as if they were local to the remote machines. We provide capabilities beyond existing disaggregation solutions by combining traditional I/O with distributed shared-memory functionality, allowing devices to become part of the same global address space as cluster applications. Software is entirely removed from the data path, and simultaneous sharing of a device among application processes running on remote hosts is enabled. Our experimental results show that I/O devices can be shared with remote hosts, achieving native PCIe performance. Thus, compared to existing device distribution mechanisms, SmartIO provides more efficient, low-cost resource sharing, increasing the overall system performance.
Rongved, Olav Andre Nergård; Hicks, Steven; Lasantha Bandara Thambawita, Vajira; Stensland, Håkon Kvale; Zouganeli, Evi & Johansen, Dag [Show all 8 contributors for this article] (2020). Real-Time Detection of Events in Soccer Videos using 3D Convolutional Neural Networks. In Bulterman, Dick; Kankanhalli, Mohan S.; Muehlhaeuser, Max; Persia, Fabio; Sheu, Phillip C.Y. & Tsai, Jeffrey J.P. (Ed.), Proceedings of the 2020 IEEE International Symposium on Multimedia (ISM). IEEE (Institute of Electrical and Electronics Engineers). ISSN 978-1-7281-8698-6. p. 135–144. doi: 10.1109/ISM.2020.00030. Full text in Research Archive
Borgli, Hanna; Lasantha Bandara Thambawita, Vajira; Smedsrud, Pia; Hicks, Steven; Jha, Debesh & Eskeland, Sigrun Losada [Show all 19 contributors for this article] (2020). HyperKvasir, a comprehensive multi-class image and video dataset for gastrointestinal endoscopy. Scientific Data. ISSN 2052-4463. 7. doi: 10.1038/s41597-020-00622-y. Full text in Research Archive Show summary
Artificial intelligence is currently a hot topic in medicine. However, medical data is often sparse and hard to obtain due to legal restrictions and lack of medical personnel for the cumbersome and tedious process to manually label training data. These constraints make it difficult to develop systems for automatic analysis, like detecting disease or other lesions. In this respect, this article presents HyperKvasir, the largest image and video dataset of the gastrointestinal tract available today. The data is collected during real gastro- and colonoscopy examinations at Bærum Hospital in Norway and partly labeled by experienced gastrointestinal endoscopists. The dataset contains 110,079 images and 374 videos, and represents anatomical landmarks as well as pathological and normal findings. The total number of images and video frames together is around 1 million. Initial experiments demonstrate the potential benefits of artificial intelligence-based computer-assisted diagnosis systems. The HyperKvasir dataset can play a valuable role in developing better algorithms and computer-assisted examination systems not only for gastro- and colonoscopy, but also for other fields in medicine.
Lasantha Bandara Thambawita, Vajira; Hicks, Steven; Borglia, Hanna; Stensland, Håkon Kvale; Jha, Debesh & Svensen, Martin Kristoffer [Show all 26 contributors for this article] (2020). PMData: a sports logging dataset. In Alay, Özgü & Toni, Laura (Ed.), MMSys '20: Proceedings of the 11th ACM Multimedia Systems Conference. Association for Computing Machinery (ACM). ISSN 978-1-4503-6845-2. p. 231–236. doi: 10.1145/3339825.3394926. Full text in Research Archive
Rosenblad, Jon-Magnus; Hicks, Steven; Stensland, Håkon Kvale; Haugen, Trine B.; Halvorsen, Pål & Riegler, Michael (2019). Using 2D and 3D convolutional neural networks to predict semen quality. CEUR Workshop Proceedings. ISSN 1613-0073. 2670.
Hicks, Steven; Riegler, Michael; Smedsrud, Pia; Haugen, Trine B.; Randel, Kristin Ranheim & Pogorelov, Konstantin [Show all 13 contributors for this article] (2019). ACM Multimedia BioMedia 2019 Grand Challenge Overview. In Gravier, Guillaume; Hung, Hayley; Ngo, Chong-Wah & Ooi, Wei Tsang (Ed.), Proceedings of the 27th ACM International Conference on Multimedia. ACM Publications. ISSN 978-1-4503-6889-6. p. 2563–2567. doi: 10.1145/3343031.3356058.
Lux, Mathias; Halvorsen, Pål; Dang Nguyen, Duc Tien; Stensland, Håkon Kvale; Kesavulu, Manjo & Potthast, Martin [Show all 7 contributors for this article] (2019). Summarizing E-Sports Matches and Tournaments - The Example of Counter-Strike: Global Offensive. In Montagud, Mario; De Simone, Fransesca & Murray, Naill (Ed.), Proceedings of the 11th ACM Workshop on Immersive Mixed and Virtual Environment Systems. ACM Publications. ISSN 978-1-4503-6299-3. p. 13–18. doi: 10.1145/3304113.3326116.
Borgli, Rune Johan; Stensland, Håkon Kvale; Halvorsen, Pål & Riegler, Michael Alexander (2019). Saga: An Open Source Platform for Training Machine Learning Models and Community-driven Sharing of Techniques, Proceedings of Content Based Multimedia Information (CBMI 2019). IEEE conference proceedings. ISSN 978-1-7281-4673-7. doi: 10.1109/CBMI.2019.8877455.
Markussen, Jonas Sæther; Kristiansen, Lars Bjørlykke; Borgli, Rune Johan; Stensland, Håkon Kvale; Seifert, Friedrich & Riegler, Michael Alexander [Show all 7 contributors for this article] (2019). Flexible device compositions and dynamic resource sharing in PCIe interconnected clusters using Device Lending. Cluster Computing. ISSN 1386-7857. 22(86), p. 1–24. doi: 10.1007/s10586-019-02988-0. Full text in Research Archive
Jeppsson, Mattis; Espeland, Håvard; Kupka, Tomas; Langseth, Ragnar; Petlund, Andreas & Peng, Qiaoqiao [Show all 13 contributors for this article] (2019). Efficient live and on-demand tiled HEVC 360 VR video streaming. International Journal of Semantic Computing (IJSC). ISSN 1793-351X. 13(3), p. 367–391. doi: 10.1142/S1793351X19400166. Full text in Research Archive
Henriksen, Fredrik Lund; Jensen, Rune; Stensland, Håkon Kvale; Johansen, Dag; Riegler, Michael & Halvorsen, Pål (2019). Performance of data enhancements and training optimization for neural network: A polyp detection case study. IEEE International Symposium on Computer-Based Medical Systems. ISSN 2372-9198. doi: 10.1109/CBMS.2019.00067. Full text in Research Archive
Borgli, Rune Johan; Halvorsen, Pål; Riegler, Michael & Stensland, Håkon Kvale (2019). Automatic Hyperparameter Optimization for Transfer Learning on Medical Image Datasets Using Bayesian Optimization. International Symposium on Medical Information and Communication Technology. ISSN 2326-828X. 2019-May. doi: 10.1109/ISMICT.2019.8743779.
Velazquez-Garcia, Francisco Javier; Halvorsen, Pål; Stensland, Håkon Kvale & Eliassen, Frank (2018). Dynamic Adaptation of Multimedia Presentations for Videoconferencing in Application Mobility. IEEE International Conference on Multimedia and Expo. ISSN 1945-7871. 2018-July, p. 1–6. doi: 10.1109/ICME.2018.8486565.
Markussen, Jonas Sæther; Kristiansen, Lars Bjørlykke; Stensland, Håkon Kvale; Seifert, Friedrich; Griwodz, Carsten & Halvorsen, Pål (2018). Flexible device sharing in PCIe clusters using device lending. In Silla, Federico & Cecilia, José M. (Ed.), Proceedings of the 47th International Conference on Parallel Processing Companion. Association for Computing Machinery (ACM). ISSN 978-1-4503-6523-9. p. 48:1–48:10. doi: 10.1145/3229710.3229759.
Gaddam, Vamsidhar Reddy; Langseth, Ragnar; Stensland, Håkon Kvale; Griwodz, Carsten; Riegler, Michael & Kupka, Tomas [Show all 10 contributors for this article] (2018). Camera Synchronization for Panoramic Videos. In Montagud, Mario; Cesar, Pablo; Boronat, Fernando & Jansen, Jack (Ed.), MediaSync: Handbook on Multimedia Synchronization. Springer. ISSN 978-3-319-65840-7. p. 565–592. doi: 10.1007/978-3-319-65840-7_20.
Velazquez-Garcia, Francisco Javier; Halvorsen, Pål; Stensland, Håkon Kvale & Eliassen, Frank (2018). Autonomic adaptation of multimedia content adhering to application mobility. Lecture Notes in Computer Science (LNCS). ISSN 0302-9743. 10853 LNCS, p. 153–168. doi: 10.1007/978-3-319-93767-0_11. Full text in Research Archive
Stokke, Kristoffer Robin; Stensland, Håkon Kvale; Griwodz, Carsten & Halvorsen, Pål (2017). Load Balancing of Multimedia Workloads for Energy Efficiency on the Tegra K1 Multicore Architecture. In Chen, Kuan-ta; Cesar, Pablo & Hsu, Cheng-Hsin (Ed.), Proceedings of the 8th ACM on Multimedia Systems Conference. Association for Computing Machinery (ACM). ISSN 978-1-4503-5002-0. p. 124–135. doi: 10.1145/3083187.3083195.
Pogorelov, Konstantin; Eskeland, Sigrun Losada; de Lange, Thomas; Griwodz, Carsten; Randel, Kristin Ranheim & Stensland, Håkon Kvale [Show all 11 contributors for this article] (2017). A Holistic Multimedia System for Gastrointestinal Tract Disease Detection. In Chen, Kuan-ta; Cesar, Pablo & Hsu, Cheng-Hsin (Ed.), Proceedings of the 8th ACM on Multimedia Systems Conference. Association for Computing Machinery (ACM). ISSN 978-1-4503-5002-0. p. 112–123. doi: 10.1145/3083187.3083189.
Bjørlykke Kristiansen, Lars; Markussen, Jonas; Stensland, Håkon Kvale; Riegler, Michael; Kohmann, Hugo & Seifert, Friedrich [Show all 9 contributors for this article] (2016). Device lending in PCI express networks . In Hellwagner, Hermann (Eds.), Proceedings of the ACM Workshop on Network and Operating Systems Support for Digital Audio and Video (NOSSDAV 2016). ACM Publications. ISSN 978-1-4503-4356-5. doi: 10.1145/2910642.2910650.
Stokke, Kristoffer Robin; Stensland, Håkon Kvale; Halvorsen, Pål & Griwodz, Carsten (2016). High-Precision Power Modelling of the Tegra K1 Variable SMP Processor Architecture. In Le Beux, Sébastien (Eds.), Proceedings of IEEE 10th International Symposium on Embedded Multicore/Many-core Systems-on-Chip. IEEE (Institute of Electrical and Electronics Engineers). ISSN 978-1-5090-3530-4. p. 193–200. doi: 10.1109/MCSoC.2016.28.
Riegler, Michael; Larson, Martha; SPAMPINATO, CONCETTO; Halvorsen, Pål; Lux, Mathias & Markussen, Jonas [Show all 9 contributors for this article] (2016). Right inflight? A dataset for exploring the automatic prediction of movies suitable for a watching situation. In Timmerer, Christian (Eds.), Proceedings of the 7th International Conference on Multimedia Systems. Association for Computing Machinery (ACM). ISSN 978-1-4503-4297-1. doi: 10.1145/2910017.2910619.
Pogorelov, Konstantin; Riegler, Michael; Markussen, Jonas; Stensland, Håkon Kvale; Halvorsen, Pål & Griwodz, Carsten [Show all 8 contributors for this article] (2016). Efficient Processing of Videos in a Multi-Auditory Environment Using Device Lending of GPUs. In Timmerer, Christian (Eds.), Proceedings of the 7th International Conference on Multimedia Systems. Association for Computing Machinery (ACM). ISSN 978-1-4503-4297-1. doi: 10.1145/2910017.2910636. Show summary
In this paper, we present a demo that utilizes Device Lending via PCI Express (PCIe) in the context of a multi-auditory environment. Device Lending is a transparent, low-latency cross-machine PCIe device sharing mechanism without any the need for implementing application-specific distribution mechanisms. As workload, we use a computer-aided diagnosis system that is used to automatically find polyps and mark them for medical doctors during a colonoscopy. We choose this scenario because one of the main requirements is to perform the analysis in real-time. The demonstration consists of a setup of two computers that demonstrates how Device Lending can be used to improve performance, as well as its effect of providing the performance needed for real-time feedback. We also present a performance evaluation that shows its real-time capabilities of it.
Riegler, Michael; Pogorelov, Konstantin; Markussen, Jonas; Lux, Mathias; Stensland, Håkon Kvale & de Lange, Thomas [Show all 11 contributors for this article] (2016). Computer aided disease detection system for gastrointestinal examinations. In Timmerer, Christian (Eds.), Proceedings of the 7th International Conference on Multimedia Systems. Association for Computing Machinery (ACM). ISSN 978-1-4503-4297-1. doi: 10.1145/2910017.2910629.
Stensland, Håkon Kvale; Wilhelmsen, Martin Alexander; Gaddam, Vamsidhar Reddy; Mortensen, Asgeir Oldernes; Langseth, Ragnar & Griwodz, Carsten [Show all 7 contributors for this article] (2015). Using a Commodity Hardware Video Encoder for Interactive Applications. International Journal of Multimedia Data Engineering and Management. ISSN 1947-8534. 6(3). doi: 10.4018/ijmdem.2015070102.
Langseth, Ragnar; Gaddam, Vamsidhar Reddy; Stensland, Håkon Kvale; Griwodz, Carsten; Halvorsen, Pål & Johansen, Dag (2015). An Experimental Evaluation of Debayering Algorithms on GPUs for Recording Panoramic Video in Real-Time. International Journal of Multimedia Data Engineering and Management. ISSN 1947-8534. 6(3). doi: 10.4018/ijmdem.2015070101.
Gaddam, Vamsidhar Reddy; Langseth, Ragnar; Stensland, Håkon Kvale; Griwodz, Carsten; Johansen, Dag & Halvorsen, Pål (2015). Scaling virtual camera services to a large number of users. In Ooi, Wei Tsang; Feng, Wu-chi & Liu, Feng (Ed.), MMSys '15: Proceedings of the 6th ACM Multimedia Systems Conference. Association for Computing Machinery (ACM). ISSN 978-1-4503-3351-1. p. 93–96. doi: 10.1145/2713168.2713189.
Gaddam, Vamsidhar Reddy; Langseth, Ragnar; Stensland, Håkon Kvale; Griwodz, Carsten; Halvorsen, Pål & Landsverk, Øystein Skonseng (2014). Automatic Real-Time Zooming and Panning on Salient Objects from a Panoramic Video. In Hua, Kien A.; Rui, Yong & Steinmetz, Ralf (Ed.), MM’14 Proceedings of the 2014 ACM Conference on Multimedia. Association for Computing Machinery (ACM). ISSN 978-1-4503-3063-3. p. 725–726. doi: 10.1145/2647868.2654882.
Stensland, Håkon Kvale; Gaddam, Vamsidhar Reddy; Tennøe, Marius; Helgedagsrud, Espen; Næss, Mikkel & Alstad, Henrik Kjus [Show all 9 contributors for this article] (2014). Processing Panorama Video in Real-time. International Journal of Semantic Computing (IJSC). ISSN 1793-351X. 08(02), p. 209–227. doi: 10.1142/S1793351X14400054.
Kellerer, Lorenz; Gaddam, Vamsidhar Reddy; Langseth, Ragnar; Stensland, Håkon Kvale; Griwodz, Carsten & Johansen, Dag [Show all 7 contributors for this article] (2014). Real-Time HDR Panorama Video. In Hua, Kien A.; Rui, Yong & Steinmetz, Ralf (Ed.), MM’14 Proceedings of the 2014 ACM Conference on Multimedia. Association for Computing Machinery (ACM). ISSN 978-1-4503-3063-3. p. 1205–1208. doi: 10.1145/2647868.2655049.
Mortensen, Asgeir Oldernes; Gaddam, Vamsidhar Reddy; Stensland, Håkon Kvale; Griwodz, Carsten; Johansen, Dag & Halvorsen, Pål (2014). Automatic Event Extraction and Video Summaries From Soccer Games. In Zimmermann, Roger (Eds.), MMSys '14: Proceedings of the 5th ACM Multimedia Systems Conference. ACM Publications. ISSN 978-1-4503-2705-3. p. 176–179. doi: 10.1145/2557642.2579374.
Gaddam, Vamsidhar Reddy; Langseth, Ragnar; Stensland, Håkon Kvale; Gurdjos, Pierre; Charvillat, Vincent & Griwodz, Carsten [Show all 8 contributors for this article] (2014). Be Your Own Cameraman: Real-Time Support for Zooming and Panning into Stored and Live Panoramic Video. In Zimmermann, Roger (Eds.), MMSys '14: Proceedings of the 5th ACM Multimedia Systems Conference. ACM Publications. ISSN 978-1-4503-2705-3. p. 168–171. doi: 10.1145/2557642.2579370.
Pettersen, Svein Arne; Johansen, Dag; Johansen, Håvard; Berg-Johansen, Vegard; Gaddam, Vamsidhar Reddy & Mortensen, Asgeir Oldernes [Show all 10 contributors for this article] (2014). Soccer Video and Player Position Dataset. In Zimmermann, Roger (Eds.), MMSys '14: Proceedings of the 5th ACM Multimedia Systems Conference. ACM Publications. ISSN 978-1-4503-2705-3. p. 18–23. doi: 10.1145/2557642.2563677.
Stensland, Håkon Kvale; Gaddam, Vamsidhar Reddy; Tennøe, Marius; Helgedagsrud, Espen; Næss, Mikkel & Alstad, Henrik Kjus [Show all 14 contributors for this article] (2014). Bagadus: An integrated real-time system for soccer analytics. ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP). ISSN 1551-6857. 10:14(1s). doi: 10.1145/2541011.
Tennøe, Marius; Helgedagsrud, Espen; Stensland, Håkon Kvale; Næss, Mikkel; Alstad, Henrik Kjus & Gaddam, Vamsidhar Reddy [Show all 9 contributors for this article] (2013). Efficient Implementation and Processing of a Real-time Panorama Video Pipeline. In Lin, Qian; Muhlhauser, Max & Sheu, Phillip C.Y. (Ed.), Proceedings of the 2013 IEEE International Symposium on Multimedia ISM 2013. IEEE (Institute of Electrical and Electronics Engineers). ISSN 978-0-7695-5140-1. p. 76–83. doi: 10.1109/ISM.2013.21.
Halvorsen, Pål; Sægrov, Simen; Mortensen, Asgeir Oldernes; Kristensen, David Kai Christen; Eichhorn, Alexander & Stenhaug, Magnus [Show all 11 contributors for this article] (2013). Bagadus: An Integrated System for Arena Sports Analytics – A Soccer Case Study. In Griwodz, Carsten (Eds.), MMSys '13: Proceedings of the 4th ACM Multimedia Systems Conference. Association for Computing Machinery (ACM). ISSN 978-1-4503-1894-5. p. 48–59. doi: 10.1145/2483977.2483982.
Raaen, Kjetil; Petlund, Andreas & Stensland, Håkon Kvale (2013). Demonstrating Hundreds of AIs in One Scene. Lecture Notes in Computer Science (LNCS). ISSN 0302-9743. 8215, p. 195–199. doi: 10.1007/978-3-642-41106-9_29.
Espeland, Håvard; Stensland, Håkon Kvale; Finstad, Dag Haavi & Halvorsen, Pål (2012). Reducing Processing Demands for Multi-Rate Video Encoding: Implementation and Evaluation. International Journal of Multimedia Data Engineering and Management. ISSN 1947-8534. 3(2). doi: 10.4018/jmdem.2012040101.
Raaen, Kjetil; Espeland, Håvard; Stensland, Håkon Kvale; Petlund, Andreas; Halvorsen, Pål & Griwodz, Carsten (2012). LEARS: A Lockless, Relaxed-Atomicity State Model for Parallel Execution of a Game Server Partition. International Conference on Parallel Processing Workshops (ICPPW). ISSN 1530-2016. p. 382–389. doi: 10.1109/ICPPW.2012.55.
Sægrov, Simen; Eichhorn, Alexander; Emerslund, Jørgen; Stensland, Håkon Kvale; Griwodz, Carsten & Johansen, Dag [Show all 7 contributors for this article] (2012). Demo: BAGADUS An Integrated System for Soccer Analysis. In Bobda, Christophe (Eds.), Sixth International Conference on Distributed Smart Cameras, ICDSC 2012. IEEE conference proceedings. ISSN 978-1-4503-1772-6.
Raaen, Kjetil; Espeland, Håvard; Petlund, Andreas; Stensland, Håkon Kvale; Halvorsen, Pål & Griwodz, Carsten (2011). A Demonstration Of a Lockless, Relaxed Atomicity State Parallel Game Server (LEARS). In Shirmohammadi, Shervin (Eds.), Workshop on Network and Systems Support for Games (NetGames 2011). IEEE Press. ISSN 978-1-4577-1932-5. p. 1–3. doi: 10.1109/netgames.2011.6080994. Show summary
Games where thousands of players can interact concurrently pose many challenges with regards to the massive parallelism. Earlier work within the field suggests that this is difficult due to synchronization issues. In this paper, we present an implementation of a game server architecture based on a model that allows for massive parallelism. The system is evaluated using traces from live game sessions that has been scaled up to generate massive workloads. We measure the differences in server response time for all objects that need timely updates. We also measure how the response time for the multithreaded implementation varies with the number of threads used. Our results show that the case of implementing a game-server can actually be highly parallel problem.
Finstad, Dag Haavi; Stensland, Håkon Kvale; Espeland, Håvard & Halvorsen, Pål (2011). Improved Multi-Rate Video Encoding. In Liao, Anthony Y. H. (Eds.), International Symposium on Multimedia. IEEE Press. ISSN 978-0-7695-4589-9. p. 293–300. doi: 10.1109/ism.2011.53.
Espeland, Håvard; Beskow, Paul; Stensland, Håkon Kvale; Olsen, Preben Nenseth; Kristoffersen, Ståle B & Griwodz, Carsten [Show all 7 contributors for this article] (2011). P2G: A Framework for Distributed Real-Time Processing of Multimedia Data. In Sheu, Jang-Ping & Wang, Cho-Li (Ed.), Proceedings of the International Workshop on Scheduling and Resource Management for Parallel and Distributed Systems (SRMPDS) - The 2011 International Conference on Parallel Processing Workshops. IEEE Press. ISSN 978-0-7695-4511-0. p. 416–426. doi: 10.1109/icppw.2011.22.
Beskow, Paul; Stensland, Håkon Kvale; Espeland, Håvard; Kristiansen, Espen Angell; Olsen, Preben Nenseth & Kristoffersen, Ståle B [Show all 8 contributors for this article] (2011). Processing of Multimedia Data using the P2G Framework. In Feng, Wu-chi (Eds.), ACM International Conference on Multimedia (MM), 2011. ACM Publications. ISSN 978-1-4503-0616-4. p. 819–820. doi: 10.1145/2072298.2072475.
Stensland, Håkon Kvale; Griwodz, Carsten; Myrseth, Martin Øinæs & Halvorsen, Pål (2010). Cheat Detection Processing: A GPU versus CPU Comparison. In Cheok, Adrian David; Huang, Jiung-Yao & Ishibashi, Yutaka (Ed.), Workshop on Network and Systems Support for Games (NetGames 2010). IEEE conference proceedings. ISSN 978-1-4244-8354-9.
Stensland, Håkon Kvale; Espeland, Håvard; Griwodz, Carsten & Halvorsen, Pål (2010). Tips, Tricks and Troubles: Optimizing for Cell and GPU. In Bulterman, Dick C. A. (Eds.), The 20th International Workshop on Network and Operating Systems Support for Digital Audio and Video (NOSSDAV 2010). ACM Publications. ISSN 978-1-4503-0043-8.
Lunde, Carl Henrik Holth; Espeland, Håvard; Stensland, Håkon Kvale & Halvorsen, Pål (2009). Improving File Tree Traversal Performance by Scheduling I/O Operations in User space. In Sheng, Zhong (Eds.), Proceedings of the 28th IEEE International Performance Computing and Communications Conference. IEEE conference proceedings. ISSN 978-1-4244-5736-6.
Lunde, C.H.; Espeland, H.; Stensland, Håkon Kvale; Halvorsen, Pål & Petlund, Andreas (2009). Improving Disk I/O Performance on Linux. In Wetter, Dirk (Eds.), UpTimes - Proceedings of Linux-Kongress and OpenSolaris Developer Conference 2009. German Unix User Group. ISSN 978-3-86541-358-1. p. 61–70.
Espeland, Håvard; Lunde, C.H.; Stensland, Håkon Kvale; Griwodz, Carsten & Halvorsen, Pål (2008). Transparent Protocol Translation and Load Balancing on a Network Processor in a Media Streaming Scenario. In Griwodz, Carsten & Wolf, Lars (Ed.), Network and Operating System Support for Digital Audio and Video, 18th International Workshop, NOSSDAV 2008,. Association for Computing Machinery (ACM). ISSN 978-1-60558-157-6. p. 129–130.
Stensland, Håkon Kvale; Griwodz, Carsten & Halvorsen, Pål (2008). Evaluation of Multi-Core Scheduling Mechanisms for Heterogeneous Processing Architectures. In Griwodz, Carsten & Wolf, Lars (Ed.), Network and Operating System Support for Digital Audio and Video, 18th International Workshop, NOSSDAV 2008,. Association for Computing Machinery (ACM). ISSN 978-1-60558-157-6. p. 33–38. Show summary
Abstract = General-purpose CPUs with multiple cores are established products, and new heterogeneous technology like the Cell broadband engine and general-purpose GPUs bring an even higher degree of true multi-processing into the market. However, means for utilizing the processing power is immature. Current tools typically assume that exclusive use of these resources is sufficient, but this assumption will soon be invalid because the interest in using their processing power for general-purpose tasks. Among the applications that can benefit from such technology is transcoding support for distributed media applications, where remote participants join and leave dynamically. Transcoding consists of several clearly separated processing operations that consume a lot of resources,such that individual processing units are unable to handle all operations of a session of arbitrary size. The individual operations can then be distributed over several processing units, and data must be moved between them according to the dependencies between operations. Many multi-processor scheduling approaches exist, but to the best of our knowledge, a challenge is still to find mechanisms that can schedule dynamic workloads of communicating operations while taking both the processing and communication requirements into account. For such applications, we believe that feasible scheduling can be performed in two levels, i.e., divided into the task of placing a job onto a processing unit and the task of multitasking time-slices within a single processing unit. We have implemented some simple high-level scheduling mechanisms and simulated a video conferencing scenario running on topologies inspired by existing systems from Intel, AMD, IBM and nVidia. Our results show the importance of using an efficient high-level scheduler.
Espeland, H.; Lunde, C.H.; Stensland, Håkon Kvale; Griwodz, Carsten & Halvorsen, Pål (2007). Transparent Protocol Translation for Streaming. In Lienhart, Rainer & Prasad, Anand R. (Ed.), ACM International Multimedia Conference (ACM MM). Association for Computing Machinery (ACM). ISSN 978-1-59593-702-5. p. 771–774.

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Borgli, Rune Johan; Pogorelov, Konstantin; Riegler, Michael; Markussen, Jonas Sæther; Stensland, Håkon Kvale & Halvorsen, Pål [Show all 9 contributors for this article] (2019). Efficient Processing of Medical Videos in a Multi-auditory Environment Using Gpu Lending.
Pogorelov, Konstantin; Eskeland, Sigrun Losada; de Lange, Thomas; Griwodz, Carsten; Randel, Kristin Ranheim & Stensland, Håkon Kvale [Show all 11 contributors for this article] (2017). A Holistic Multimedia System for Gastrointestinal Tract Disease Detection.
Stokke, Kristoffer Robin; Stensland, Håkon Kvale; Halvorsen, Pål & Griwodz, Carsten (2016). A High Precision Power Model for the Tegra K1 CPU, GPU and RAM".
Stokke, Kristoffer Robin; Stensland, Håkon Kvale; Griwodz, Carsten & Halvorsen, Pål (2016). A high-precision, hybrid GPU, CPU and RAM power model for generic multimedia workloads.
Stokke, Kristoffer Robin; Stensland, Håkon Kvale; Griwodz, Carsten & Halvorsen, Pål (2015). Energy Efficient Continuous Multimedia Processing Using the Tegra K1 Mobile SoC.
Stokke, Kristoffer Robin; Stensland, Håkon Kvale; Halvorsen, Pål & Griwodz, Carsten (2015). Why Race-to-Finish is Energi-Inefficient for Continuous Multimedia Workloads.
Gaddam, Vamsidhar Reddy; Langseth, Ragnar; Stensland, Håkon Kvale; Griwodz, Carsten; Halvorsen, Pål & Johansen, Dag (2015). Scaling virtual camera services to a large number of users.
Stokke, Kristoffer Robin; Stensland, Håkon Kvale; Halvorsen, Pål & Griwodz, Carsten (2015). Energy Efficient Video Encoding Using the Tegra K1 Mobile Processor.
Stokke, Kristoffer Robin; Stensland, Håkon Kvale & Halvorsen, Pål (2015). Energy and Performance Optimisation of a Simple Video Encoder on the JetsonTK1.
Kellerer, Lorenz; Gaddam, Vamsidhar Reddy; Langseth, Ragnar; Stensland, Håkon Kvale; Griwodz, Carsten & Johansen, Dag [Show all 7 contributors for this article] (2014). Real-Time HDR Panorama Video.
Mortensen, Asgeir Oldernes; Gaddam, Vamsidhar Reddy; Stensland, Håkon Kvale; Griwodz, Carsten; Johansen, Dag & Halvorsen, Pål (2014). Automatic Event Extraction and Video Summaries From Soccer Games.
Gaddam, Vamsidhar Reddy; Langseth, Ragnar; Stensland, Håkon Kvale; Gurdjos, Pierre; Charvillat, Vincent & Griwodz, Carsten [Show all 8 contributors for this article] (2014). Be Your Own Cameraman: Real-Time Support for Zooming and Panning into Stored and Live Panoramic Video.
Pettersen, Svein Arne; Johansen, Dag; Johansen, Håvard; Berg-Johansen, Vegard; Gaddam, Vamsidhar Reddy & Mortensen, Asgeir Oldernes [Show all 10 contributors for this article] (2014). Soccer Video and Player Position Dataset.
Tennøe, Marius; Helgedagsrud, Espen; Næss, Mikkel; Alstad, Henrik Kjus; Stensland, Håkon Kvale & Gaddam, Vamsidhar Reddy [Show all 9 contributors for this article] (2013). Efficient Implementation and Processing of a Real-time Panorama Video Pipeline.
Halvorsen, Pål; Sægrov, Simen; Mortensen, Asgeir Oldernes; Kristensen, David Kai Christen; Eichhorn, Alexander & Stenhaug, Magnus [Show all 11 contributors for this article] (2013). Bagadus: An Integrated System for Arena Sports Analytics – A Soccer Case Study.
Sægrov, Simen; Eichhorn, Alexander; Emerslund, Jørgen; Stensland, Håkon Kvale; Griwodz, Carsten & Johansen, Dag [Show all 7 contributors for this article] (2012). BAGADUS: An Integrated System for Soccer Analysis (Demo).
Espeland, H.; Lunde, C.H.; Stensland, Håkon Kvale; Griwodz, Carsten & Halvorsen, Pål (2007). Transparent Protocol Translation for Streaming.
Stensland, Håkon Kvale; Halvorsen, Pål & Griwodz, Carsten (2015). Processing Multimedia Workloads on Heterogeneous Multicore Architectures. Akademika Publishing. ISSN 1501-7710. Full text in Research Archive Show summary
Processor architectures have been evolving quickly since the introduction of the central processing unit. For a very long time, one of the important means of increasing per- formance was to increase the clock frequency. However, in the last decade, processor manufacturers have hit the so-called power wall, with high heat dissipation. To overcome this problem, processors were designed with reduced clock frequencies but with multiple cores and, later, heterogeneous processing elements. This shift introduced a new challenge for programmers: Legacy applications, written without parallelization in mind, gain no benefits from moving to multicore and heterogeneous architectures. Another challenge for the programmers is that heterogeneous architecture designs are very different with respect to caches, memory types, execution unit organization, and so forth and, in the worst case, a programmer must completely rewrite the application to obtain the best performance on the new architecture. Multimedia workloads, such as video encoding, are often time sensitive and interac- tive. These workloads differ from traditional batch processing workloads with no real-time requirements. This work investigates how to use modern heterogeneous architectures ef- ficiently to process multimedia workloads. To do so, we investigate both simple and complex workloads on multiple architectures to learn about the properties of these archi- tectures. When programing multimedia workloads, it is very important to know how the algorithms perform on the target architecture. In addition, achieving high performance on heterogeneous architectures is not a trivial task, often requiring detailed knowledge about the architecture. We therefore evaluate several optimizations so we can learn how best to write programs for these architectures and avoid potential pitfalls. We later use the knowledge gained to propose a framework design and language called Parallel Pro- cessing Graph (P2G). The P2G framework is designed for multimedia workloads and supports heterogeneous architectures. To demonstrate the feasibility of the framework, we construct a proof-of-concept implementation. Two simple workloads show that we can express multimedia workloads in the system. We also demonstrate the scalability of the designed solution.

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Published June 30, 2011 7:47 AM - Last modified Mar. 11, 2022 1:30 PM

Research groups

Networks and Distributed Systems (ND)