Håkon Kvale Stensland

Dr. Håkon Kvale Stensland

orcid

Research Focus & Metrics

Academic Career Length

14Years (2013-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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31 May 2020 in ACM Transactions on Computer Systems
Verified
Journal Article
Open access
JMJonas Markussen
Jonas Markussen
LKLars Bjørlykke Kristiansen
Lars Bjørlykke Kristiansen
Pål HalvorsenPål Halvorsen
Pål Halvorsen
HKHalvor Kielland-Gyrud
Halvor Kielland-Gyrud
HSHåkon Kvale Stensland
Håkon Kvale Stensland
CGCarsten Griwodz
Carsten Griwodz
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.

1 December 2013
Verified
Conference Paper
Closed access
MTMarius Tennoe
Marius Tennoe
EHEspen Helgedagsrud
Espen Helgedagsrud
MNMikkel Naess
Mikkel Naess
HAHenrik Kjus Alstad
Henrik Kjus Alstad
HSHåkon Kvale Stensland
Håkon Kvale Stensland
Pål HalvorsenPål Halvorsen
Pål Halvorsen
High resolution, wide field of view video generated from multiple camera feeds has many use cases. However, processing the different steps of a panorama video pipeline in real-time is challenging due to the high data rates and the stringent requirements of timeliness. We use panorama video in a sport analysis system where video events must be generated in real-time. In this respect, we present a system for real-time panorama video generation from an array of low-cost CCD HD video cameras. We describe how we have implemented different components and evaluated alternatives. We also present performance results with and without co-processors like graphics processing units (GPUs), and we evaluate each individual component and show how the entire pipeline is able to run in real-time on commodity hardware.

1 December 2018
Verified
Conference Paper
Closed access
TBTor Jan Derek Berstad
Tor Jan Derek Berstad
Michael Alexander RieglerMichael Alexander Riegler
Michael Alexander Riegler
HEHavard Espeland
Havard Espeland
TLThomas de Lange
Thomas de Lange
PSPia Helen Smedsrud
Pia Helen Smedsrud
Pål HalvorsenPål Halvorsen
Pål Halvorsen
The interest in neural networks has increased significantly, and the application of this type of machine learning is vast, ranging from natural image classification to medical image segmentation. However, many users of neural networks tend to use them as a black box tool. They do not access all of the possible variations, nor take into account the respective classification accuracies and costs. In our work, we focus on multiclass image classification, and in this research, we shed light on the trade-offs between systems using a single multiclass classification and multiple binary classifiers, respectively. We have tested these classifiers on several modern neural network architectures, including DenseNet, Inception v3, Inception ResNet v2, Xception, NASNet and MobileNet. We have compared several aspects of the performance of these architectures during training and testing using both classification styles in terms of classification speed and several classification accuracy metrics. Here, we present the results from experiments on a total of 99 networks: 11 multiclass and 88 individual binary networks, for an 8-class classification of medical images. In short, using multiple binary classification networks resulted in a more robust model (less variance) for the task at hand. However, on average, such a multi-network style performed the classification 7.6 times slower compared to a single network multiclass implementation. These collective findings show that both approaches can be applied to modern neural network structures. Several binary networks can often give more robust and increased classification accuracy, but at the cost of classification speed and resources consumption.

10 May 2016
Verified
Conference Paper
Open access
Michael Alexander RieglerMichael Alexander Riegler
Michael Alexander Riegler
KPKonstantin Pogorelov
Konstantin Pogorelov
JMJonas Markussen
Jonas Markussen
MLMathias Lux
Mathias Lux
HSHåkon Kvale Stensland
Håkon Kvale Stensland
SESigrun L. Eskeland
Sigrun L. Eskeland
In this paper, we present the computer-aided diagnosis part of the EIR system [9], which can support medical experts in the task of detecting diseases and anatomical landmarks in the gastrointestinal (GI) system. This includes automatic detection of important findings in colonoscopy videos and marking them for the doctors. EIR is designed in a modular way so that it can easily be extended for other diseases. For this demonstration, we will focus on polyp detection, as our system is trained with the ASU-Mayo Clinic polyp database [5].

30 September 2019 in International Journal of Semantic Computing
Verified
Journal Article
Open access
PDF file
MJMattis Jeppsson
Mattis Jeppsson
HEHåvard N. Espeland
Håvard N. Espeland
TKTomas Kupka
Tomas Kupka
RLRagnar Langseth
Ragnar Langseth
APAndreas Petlund
Andreas Petlund
Pål HalvorsenPål Halvorsen
Pål Halvorsen
360∘ panorama video displayed through Virtual Reality (VR) glasses or large screens offers immersive user experiences, but as such technology becomes commonplace, the need for efficient streaming methods of such high-bitrate videos arises. In this respect, the attention that 360∘ panorama video has received lately is huge. Many methods have already been proposed, and in this paper, we shed more light on the different trade-offs in order to save bandwidth while preserving the video quality in the user’s field-of-view (FoV). Using 360∘ VR content delivered to a Gear VR head-mounted display with a Samsung Galaxy S7 and to a Huawei Q22 set-top-box, we have tested various tiling schemes analyzing the tile layout, the tiling and encoding overheads, mechanisms for faster quality switching beyond the DASH segment boundaries and quality selection configurations. In this paper, we present an efficient end-to-end design and real-world implementation of such a 360∘ streaming system. Furthermore, in addition to researching an on-demand system, we also go beyond the existing on-demand solutions and present a live streaming system which strikes a trade-off between bandwidth usage and the video quality in the user’s FoV. We have created an architecture that combines RTP and DASH, and our system multiplexes a single HEVC hardware decoder to provide faster quality switching than at the traditional GOP boundaries. We demonstrate the performance and illustrate the trade-offs through real-world experiments where we can report comparable bandwidth savings to existing on-demand approaches, but with faster quality switches when the FoV changes.

1 December 2014
Verified
Conference Paper
Closed access
MWMartin Alexander Wilhelmsen
Martin Alexander Wilhelmsen
HSHåkon Kvale Stensland
Håkon Kvale Stensland
VGVamsidhar Reddy Gaddam
Vamsidhar Reddy Gaddam
AMAsgeir Mortensen
Asgeir Mortensen
RLRagnar Langseth
Ragnar Langseth
Pål HalvorsenPål Halvorsen
Pål Halvorsen
Over the last years, video streaming has become one of the most dominant Internet services. A trend now is that due to the increased availability of high-speed internet access, multimedia services are becoming more interactive and immersive. Examples of such applications are both cloud gaming and systems where users can interact with high-resolution content. Over the last few years, hardware video encoders have been built into commodity hardware. We evaluate one of these encoders in a scenario where we have individual streams delivered to the end users. Our results show that we can reduce almost half of the CPU time spent on video processing, while also greatly reducing the power consumption on the system. We also compare the visual video quality and the frame size of the hardware based encoder, and we find no significant difference compared to a software based approach.