Title:
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Performance impact of unaligned memory operations in SIMD extensions for video CODEC applications
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Author:
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Álvarez Mesa, Mauricio; Salamí San Juan, Esther; Ramírez Bellido, Alejandro; Valero Cortés, Mateo
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Other authors:
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Universitat Politècnica de Catalunya. Departament d'Arquitectura de Computadors; Universitat Politècnica de Catalunya. CAP - Grup de Computació d'Altes Prestacions |
Abstract:
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Although SIMD extensions are a cost effective way to exploit the data level parallelism present in most media applications, we will show that they had have a very limited memory architecture with a weak support for unaligned memory accesses. In video codec, and other applications, the overhead for accessing unaligned positions without an efficient architecture support has a big performance penalty and in some cases makes vectorization counter-productive. In this paper we analyze the performance impact of extending the Altivec SIMD ISA with unaligned memory operations. Results show that for several kernels in the H.264/AVC media codec, unaligned access support provides a speedup up to 3.8times compared to the plain SIMD version, translating into an average of 1.2times in the entire application. In addition to providing a significant performance advantage, the use of unaligned memory instructions makes programming SIMD code much easier both for the manual developer and the auto vectorizing compiler |
Abstract:
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Peer Reviewed |
Subject(s):
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-Àrees temàtiques de la UPC::Enginyeria de la telecomunicació::Processament del senyal::Processament de la imatge i del senyal vídeo -Video compression -Parallel processing (Electronic computers) -Digital video -Video coding -Memory architecture -Multimedia computing -Video codecs -Compressió de vídeo -Processament en paral·lel (Ordinadors) -Vídeo digital |
Rights:
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Document type:
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Article - Published version Conference Object |
Published by:
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Institute of Electrical and Electronics Engineers (IEEE)
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