| 1. |
- Brorsson, Mats, 1962-, et al.
(författare)
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Adaptive and flexible dictionary code compression for embedded applications
- 2006
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Ingår i: Proceedings of the 2006 international conference on Compilers, architecture and synthesis for embedded systems. - New York, NY, USA : ACM. - 1595935436 ; , s. 113-124
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Konferensbidrag (refereegranskat)abstract
- Dictionary code compression is a technique where long instructions in the memory are replaced with shorter code words used as index in a table to look up the original instructions. We present a new view of dictionary code compression for moderately high-performance processors for embedded applications. Previous work with dictionary code compression has shown decent performance and energy savings results which we verify with our own measurement that are more thorough than previously published. We also augment previous work with a more thorough analysis on the effects of cache and line size changes. In addition, we introduce the concept of aggregated profiling to allow for two or more programs to share the same dictionary contents. Finally, we also introduce dynamic dictionaries where the dictionary contents is considered to be part of the context of a process and show that the performance overhead of reloading the dictionary contents on a context switch is negligible while on the same time we can save considerable energy with a more specialized dictionary contents.
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| 2. |
- Collin, David, et al.
(författare)
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Added value of interpreter experience in occult and suspect hip fractures: a retrospective analysis of 254 patients.
- 2016
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Ingår i: Emergency Radiology. - : Springer Science and Business Media LLC. - 1438-1435 .- 1070-3004. ; 23:3, s. 229-234
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Tidskriftsartikel (refereegranskat)abstract
- The influence of experience in categorizing suspect and occult fractures on radiography compared to MRI and clinical outcome has not been studied. The aim of this study is to evaluate the importance of experience in diagnosing normal or suspect hip radiographs compared to MRI. Primarily reported normal or suspect radiography in 254 patients with low-energy hip trauma and subsequent MRI was re-evaluated by two experienced reviewers. Primary readings and review were compared. The prevalence of fractures among normal and suspect radiographic studies was assessed. Clinical outcome was used as reference. At review of radiography, 44 fractures (17 %) were found. Significantly more fractures were found among suspect cases than among normal cases. At MRI, all 44 fractures were confirmed, and further 64 fractures were detected (25 %). MRI detected all fractures with no missed fractures revealed at follow-up. There were a significantly higher proportion of fractures at MRI among the suspect radiographic diagnoses for both the primary report and at review than among occult cases. The more experienced reviewers classified radiography examinations with higher accuracy than primary reporting general radiologists. There was almost complete agreement on MRI diagnoses.
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| 3. |
- Collin, Mikael, et al.
(författare)
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A performance and energy exploration of dictionary code compression architectures
- 2011
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Ingår i: 2011 International Green Computing Conference and Workshops (IGCC). - : IEEE conference proceedings. - 9781457712227 ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- We have made a performance and energy exploration of a previously proposed dictionary code compression mechanism where frequently executed individual instructions and/or sequences are replaced in memory with short code words. Our simulated design shows a dramatically reduced instruction memory access frequency leading to a performance improvement for small instruction cache sizes and to significantly reduced energy consumption in the instruction fetch path. We have evaluated the performance and energy implications of three architectural parameters: branch prediction accuracy, instruction cache size and organization. To asses the complexity of the design we have implemented the critical stages in VHDL.
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| 4. |
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| 5. |
- Collin, Mikael, et al.
(författare)
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Improving Code Density of Embedded Software using a 2-level Dictionary Code Compression Architecture
- 2008
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Ingår i: 2008 13TH ASIA-PACIFIC COMPUTER SYSTEMS ARCHITECTURE CONFERENCE. - NEW YORK : IEEE. ; , s. 284-291
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Konferensbidrag (refereegranskat)abstract
- Dictionary code compression has been proposed to reduce the energy consumed in the instruction fetch path of processors or to reduce program footprint in memory With this technique, instructions, or instruction sequences, are in the binary code replaced with short code words that in run-time are replaced with the original instructions using the dictionary inside the data-path. We present here a new method with the aim to further improve on code density as compared to previously proposed dictionary code compression techniques. It is a 2-level approach capable of handling compression of both individual instructions and code sequences of 2-16 instructions. Our proposed approach is more flexible and has better dynamic compression ratio and fetch path energy consumption as compared to previously studied 1-level approaches. The energy consumed in the instruction fetch path is reduced with up to 56% as compared to using uncompressed instructions.
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| 6. |
- Collin, Mikael, et al.
(författare)
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Low Power Instruction Fetch using Profiled Variable Length Instructions
- 2003
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Konferensbidrag (refereegranskat)abstract
- Computer system performance depends on high access rate and low miss rate in the instruction cache, which also affects energy consumed by fetching instructions. Simulation of a small computer typical for embedded systems show that up to 20% of the overall processor energy is consumed in the instruction fetch path and as much as 23% of the execution time is spent on instruction fetch. One way to increase the instruction memory bandwidth is to fetch more instructions each access without increasing the bus width. We propose an extension to a RISC ISA, with variable length instructions, yielding higher information density without compromising programmability. Based on profiling of dynamic instruction usage and argument locality of a set of SPEC CPU2000 applications, we present a scheme using 8- 16- and 24-bit instructions accompanied by lookup tables inside the processor. Our scheme yields a 20-30% reduction in static memory usage, and experiments show that up to 60% of all executed instructions consist of short instructions. The overall energy savings are up to 15% for the entire data path and memory system, and up to 20% in the instruction fetch path.
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| 7. |
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| 8. |
- Collin, Mikael, et al.
(författare)
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Two-Level Dictionary Code Compression : a New Scheme to Improve Instruction Code Density of Embedded Applications
- 2009
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Ingår i: CGO 2009. - LOS ALAMITOS : IEEE COMPUTER SOC. - 9780769535760 ; , s. 231-242
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Konferensbidrag (refereegranskat)abstract
- Dictionary code compression is a technique which has been studied as a method to reduce the energy consumed in the instruction fetch path of processors. Instructions or instruction sequences in the code are replaced with short code words. These code words are later used to index a dictionary which contains the original uncompressed instruction or an entire sequence. In this paper, we present a new method which improves on code density compared to previously published dictionary methods. It uses a two-level dictionary design and is capable of handling compression of both individual instructions and code sequences of 2-16 instructions. The two dictionaries are in separate pipeline stages and work together to decompress sequences and instructions. The impact on storage size for the dictionaries is rather small as the sequences in the dictionary are stored as individually compressed instructions, instead of normal instructions. Compared to previous dictionary code compression methods we achieve improved dynamic compression rate, potential for better performance with reasonable static compression rate and with still small dictionary size suitable for context switching.
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| 9. |
- Collin, Peter, et al.
(författare)
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Composite bridges with prefabricated decks
- 1998
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Ingår i: Proceedings / Nordic Steel Construction Conference 98. - Oslo : Norwegian Steel Association. - 8291466025
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Konferensbidrag (refereegranskat)
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| 10. |
- Collin, Peter, et al.
(författare)
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Innovative prefabricated composite bridges
- 2002
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Ingår i: IABSE symposium Melbourne 2002. - Zürich : International Association for Bridge and Structural Engineering.
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Konferensbidrag (refereegranskat)abstract
- The competitiveness of composite bridges depends on several circumstances such as site conditions, local costs of material and staff and the contractor's experience. One major advantage compared to concrete bridges is that the steel girders can carry the weight of the formwork and the wet concrete. Another advantage is the savings in construction time, which saves some money for the contractor but even more so for the road users, a fact that usually is neglected when evaluating alternative bridge designs. A further step to improve the competitiveness of composite bridges is to prefabricate not only the steel girders, but also the concrete deck. In this paper a new concept with dry joints between the elements is described.
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