The Linux-SRT integrated multimedia operating system: bringing QoS to the desktop

Childs, Stephen; Ingram, D.G.W.

doi:10.1109/rttas.2001.929879

Cited by 19 publications

(10 citation statements)

References 13 publications

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“…The conclusion of the first part of this work is that the effects of the scheduling policy are indeed quite heavy on real-time performance, and their importance outweighs the problems generated by the length of the noninterruptible primitives (which is being reduced by the new generation of accelerated graphical cards). This experimental observation is in perfect accordance with a similar conjecture formulated in [6]. In this case, case the authors propose a modification of the X11 server to support fixed priority scheduling.…”

Section: Introductionsupporting

confidence: 88%

QoS Support in the X11 Window System

Manica

Abeni

Palopoli

2008

2008 IEEE Real-Time and Embedded Technology and Applications Symposium

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In this paper, we consider the problem of providing QoS guarantees to the execution of applications using the X11 window system. In particular, we offer a system level analysis of the issues encountered when using X11 to serve realtime applications. By using a tracer developed for the purpose we analyse in depth the internal behaviour of the system. The result of the analysis puts on display the adverse effect played by a non real-time scheduler on the performance of time-sensitive applications. Based on this analysis, we propose an alternative solution based on the CBS scheduler and prove its effectiveness by an extensive set of experiments on real hardware.

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Section: Introductionsupporting

confidence: 88%

QoS Support in the X11 Window System

Manica

Abeni

Palopoli

2008

2008 IEEE Real-Time and Embedded Technology and Applications Symposium

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“…Many studies have recognized and tried to solve the inherent problem of general-purpose OSs not being able to adequately support multimedia and other soft realtime applications [23,1,3,2,14,7,24]. The fundamental problem is the coarse granularity of Hz (OS clock tick frequency).…”

Section: About Ticksmentioning

confidence: 99%

System noise, OS clock ticks, and fine-grained parallel applications

Tsafrir

Etsion

Feitelson

et al. 2005

Proceedings of the 19th Annual International Conference on Supercomputing

128

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As parallel jobs get bigger in size and finer in granularity, "system noise" is increasingly becoming a problem. In fact, fine-grained jobs on clusters with thousands of SMP nodes run faster if a processor is intentionally left idle (per node), thus enabling a separation of "system noise" from the computation. Paying a cost in average processing speed at a node for the sake of eliminating occasional processes delays is (unfortunately) beneficial, as such delays are enormously magnified when one late process holds up thousands of peers with which it synchronizes.We provide a probabilistic argument showing that, under certain conditions, the effect of such noise is linearly proportional to the size of the cluster (as is often empirically observed). We then identify a major source of noise to be indirect overhead of periodic OS clock interrupts ("ticks"), that are used by all general-purpose OSs as a means of maintaining control. This is shown for various grain sizes, platforms, tick frequencies, and OSs. To eliminate such noise, we suggest replacing ticks with an alternative mechanism we call "smart timers". This turns out to also be in line with needs of desktop and mobile computing, increasing the chances of the suggested change to be accepted.

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“…Linux-based RTOSes that exploit CPU reservation include Linux/RK (Oikawa and Rajkumar 1999), Linux-SRT (Childs and Ingram 2001), and AQuoSA (Palopoli et al 2009). Linux/RK implements both fixed-priority and EDF schedulers, though the EDF scheduler has not yet been extended to work on multicore platforms.…”

Section: Linux-based Rtoses and Cpu Schedulingmentioning

confidence: 99%

CPU scheduling and memory management for interactive real-time applications

2011

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In this paper, we propose, design, implement, and evaluate a CPU scheduler and a memory management scheme for interactive soft real-time applications. Our CPU scheduler provides a new CPU reservation algorithm that is based on the well-known Constant Bandwidth Server (CBS) algorithm but is more flexible in allocating the CPU time to multiple concurrently-executing real-time applications. Our CPU scheduler also employs a new multicore scheduling algorithm, extending the Earliest Deadline First to yield Window-constraint Migrations (EDF-WM) algorithm, to improve the absolute CPU bandwidth available in reservation-based systems. Furthermore, we propose a memory reservation mechanism incorporating a new paging algorithm, called Private-Shared-Anonymous Paging (PSAP). This PSAP algorithm allows interactive real-time applications to be responsive under memory pressure without wasting and compromising the memory resource available for contending best-effort applications. Our evaluation demonstrates that our CPU scheduler enables the simultaneous playback of multiple movies to perform at the stable framerates more than existing real-time CPU schedulers, while also improves the ratio of hard-deadline guarantee for randomly-generated task sets. Furthermore, we show that our memory management scheme can protect the simultaneous playback of multiple movies from the interference introduced by memory pressure, whereas these movies can become unresponsive under existing memory management schemes.

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The Linux-SRT integrated multimedia operating system: bringing QoS to the desktop

Cited by 19 publications

References 13 publications

QoS Support in the X11 Window System

QoS Support in the X11 Window System

System noise, OS clock ticks, and fine-grained parallel applications

CPU scheduling and memory management for interactive real-time applications

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