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Kista, Sweden

The Swedish Institute of Computer Science, SICS, is an independent non-profit research organization with a research focus on applied computer science. The institute carries out research in a number of areas, including networked embedded systems, future Internet technologies, large scale network-based applications, and human-machine interaction. Research projects at SICS are typically carried out in cooperation with both industry and academia.In January 2005 SICS had approximately 88 employees, of which 77 are researchers and 30 have PhD degrees. The institute is located in the Kista district of Stockholm, with the main office in the Electrum building. Wikipedia.

Abrahamsson H.,Swedish Institute of Computer Science | Nordmark M.,TeliaSonera AB
Proceedings of the ACM SIGCOMM Internet Measurement Conference, IMC | Year: 2012

Today increasingly large volumes of TV and video are distributed over IP-networks and over the Internet. It is therefore essential for traffic and cache management to understand TV program popularity and access patterns in real networks. In this paper we study access patterns in a large TV-on-Demand system over four months. We study user behaviour and program popularity and its impact on caching. The demand varies a lot in daily and weekly cycles. There are large peaks in demand, especially on Friday and Saturday evenings, that need to be handled. We see that the cacheability, the share of requests that are not first-time requests, is very high. Furthermore, there is a small set of programs that account for a large fraction of the requests. We also find that the share of requests for the top most popular programs grows during prime time, and the change rate among them decreases. This is important for caching. The cache hit ratio increases during prime time when the demand is the highest, and aching makes the biggest difference when it matters most. We also study the popularity (in terms of number of requests and rank) of individual programs and how that changes over time. Also, we see that the type of programs offered determines what the access pattern will look like. © 2012 ACM. Source

Faxen K.-F.,Swedish Institute of Computer Science
Proceedings of the International Conference on Parallel Processing | Year: 2010

This paper deals with improving the performance of fine grain task parallelism. It is often either cumbersome or impossible to increase the grain size of such programs. Increasing core counts exacerbates the problem; a program that appears coarse-grained on eight cores may well look a lot more finegrained on sixty four. In this paper we present the direct task stack, a novel work stealing algorithm with unusually low overheads, both for creating tasks and for stealing. We compare the performance of our scheduler to Cilk++, the icc implementation of OpenMP 3.0 and the Intel TBB library on an eight core, dual socket Opteron machine. We also analyze the reasons why our techniques achieve consistent speed ups over the other systems ranging from 2-3x on many fine grained workloads to over 50 in extreme cases and show quantitatively how each of the techniques we use contribute to the improved performance. © 2010 IEEE. Source

Mottola L.,Swedish Institute of Computer Science
Proceedings of the 9th ACM/IEEE International Conference on Information Processing in Sensor Networks, IPSN '10 | Year: 2010

We present Squirrel, a stream-oriented programming framework for storage-centric sensor networks. The storage-centric paradigm - -where storage operations prevail over communication activity - -applies to scenarios such as batch data collection, delay-tolerant mobile applications, and disconnected operations in static networks. Squirrel simplifies developing such applications by decoupling data processing from storage, and by transparently handling the latter. We achieve this through: i) a modular programming abstraction, and ii) a lightweight run-time layer that efficiently allocates data to different storage areas, based on size vs. energy tradeoffs. We demonstrate Squirrel's effectiveness based on three real-world applications, each representing a different storage-centric scenario. The results show that - -while relieving programmers from a significant burden - -Squirrel achieves efficient utilization of storage areas, enabling energy savings independently of the storage technology. © 2010 ACM. Source

Mentis H.M.,Digital Systems | Johansson C.,Swedish Institute of Computer Science
Conference on Human Factors in Computing Systems - Proceedings | Year: 2013

With the increased availability of movement based interactive devices there is a growing interest in exploring the potential design space for engaging movement-based interactions. This has led to the exploration of different ways to sense and model movement such as Laban Movement Analysis' Effort qualities. However, little is understood in how movement qualities are perceived and experienced by users. We explored this in an interactive improvisational dance performance setting. From video analysis with a Laban Movement expert and post-performance interviews with audience members, we discuss the differences in how a movement quality was perceived. From these findings, we discuss implications for further efforts in designing interactive movement-based systems that strive to capitalize on movement qualities. Copyright © 2013 ACM. Source

Lindgren A.,Swedish Institute of Computer Science
Proceedings of the Annual International Conference on Mobile Computing and Networking, MOBICOM | Year: 2011

In this demo, we describe the design and implementation of fb-DTN, a gateway that allow users to access Facebook services over a Disruption Tolerant Network (DTN) in a convenient and secure manner. Our system enables users to read their news feed, post status updates and photos, and comment and like the posts of other people. We also show the importance of supporting applications like this in a DTN and allow demo session attendees to see this system in action. Source

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