caa a22 4500 477132871 CHVBK 20180405111708.0 cr unu---uuuuu 170330e19970601xx s 000 0 eng 10.1007/s005300050057 doi (NATIONALLICENCE)springer-10.1007/s005300050057 I/O scheduling for digital continuous media [Elektronische Daten] [Deepak R. Kenchammana-Hosekote, Jaideep Srivastava] Abstract.: A growing set of applications require access to digital video and audio. In order to provide playback of such continuous media (CM), scheduling strategies for CM data servers (CMS) are necessary. In some domains, particularly defense and industrial process control, the timing requirements of these applications are strict and essential to their correct operation. In this paper we develop a scheduling strategy for multiple access to a CMS such that the timing guarantees are maintained at all times. First, we develop a scheduling strategy for the steady state, i.e., when there are no changes in playback rate or operation. We derive an optimal Batched SCAN (BSCAN) algorithm that requires minimum buffer space to schedule concurrent accesses. The scheduling strategy incorporates two key constraints: (1) data fetches from the storage system are assumed to be in integral multiples of the block size, and (2) playback guarantees are ensured for frame-oriented streams when each frame can span multiple blocks. We discuss modifications to the scheduling strategy to handle compressed data like motion-JPEG and MPEG. Second, we develop techniques to handle dynamic changes brought about by VCR-like operations executed by applications. We define a suite of primitive VCR-like operations that can be executed. We show that an unregulated change in the BSCAN schedule, in response to VCR-like operations, will affect playback guarantees. We develop two general techniques to ensure playback guarantees while responding to VCR-like operations: passive and active accumulation. Using user response time as a metric we show that active accumulation algorithms outperform passive accumulation algorithms. An optimal response-time algorithm in a class of active accumulation strategies is derived. The results presented here are validated by extensive simulation studies. Springer-Verlag Berlin Heidelberg, 1997 Key words: Continuous media - I/O scheduling - Frame-oriented streams -VCR-like operations nationallicence Kenchammana-Hosekote Deepak R. Department of Computer Science, University of Minnesota, MN 55455, USA e-mail: {kencham,srivasta}@cs.umn.edu, US aut Srivastava Jaideep Department of Computer Science, University of Minnesota, MN 55455, USA e-mail: {kencham,srivasta}@cs.umn.edu, US aut https://doi.org/10.1007/s005300050057 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s005300050057 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kenchammana-Hosekote Deepak R. Department of Computer Science, University of Minnesota, MN 55455, USA e-mail: {kencham,srivasta}@cs.umn.edu, US aut NATIONALLICENCE 700 1- Srivastava Jaideep Department of Computer Science, University of Minnesota, MN 55455, USA e-mail: {kencham,srivasta}@cs.umn.edu, US aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer