Characteristics of deterministic optimal routing for a simple traffic control problem

Oida, Kazumasa; Shinjo, Kazumasa

doi:10.1109/pccc.1999.749463

Cited by 7 publications

(15 citation statements)

References 15 publications

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“…While a great many papers have been written comparing the response time of different task assignment policies, e.g., [6,7,10,13,14,20,28,29], all of these papers conclude (via numerical analysis, simulation, or approximation) that, for high job-size variability, the SITA policy is superior to all the other common policies above. The reason for the superiority of SITA task assignment lies in the fact that SITA allows short jobs their own "express-line," thereby giving them isolation from long jobs.…”

Section: Introductionmentioning

confidence: 99%

“…There are several papers which specifically compare the performance of SITA to LWL [4,7,9,12,13,14,20,28,29]. All of these find that as job size variability is increased, SITA becomes far superior to LWL (for low C 2 , SITA may be worse than LWL because not all servers are utilized; however, this behavior changes quickly as C 2 is increased).…”

Section: Introductionmentioning

confidence: 99%

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Surprising results on task assignment in server farms with high-variability workloads

Harchol-Balter

Scheller‐Wolf

Young³

2009

Proceedings of the Eleventh International Joint Conference on Measurement and Modeling of Computer Systems

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This paper investigates the performance of task assignment policies for server farms, as the variability of job sizes (service demands) approaches infinity. Our results reveal that some common wisdoms regarding task assignment are flawed. The SizeInterval-Task-Assignment policy (SITA), which assigns each server a unique size range, was heretofore thought of by some as the panacea for dealing with high-variability job-size distributions. We show SITA to be inferior to the much simpler greedy policy, LeastWork-Left (LWL), for certain common job-size distributions, including many modal, hyperexponential, and Pareto distributions. We also define regimes where SITA's performance is superior, and prove simple closed-form bounds on its performance for the abovementioned distributions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surprising results on task assignment in server farms with high-variability workloads

Harchol-Balter

Scheller‐Wolf

Young³

2009

Proceedings of the Eleventh International Joint Conference on Measurement and Modeling of Computer Systems

View full text Add to dashboard Cite

show abstract

“…While a great many papers have been written comparing the response time of different task assignment policies, e.g., [5], [6], [9], [11], [12], [19], [22], [23], all of these papers conclude (via numerical analysis, simulation, or approximation) that, for high job-size variability, the SITA policy is superior to all the other common policies mentioned above. The reason for the superiority of SITA task assignment lies in the fact that SITA allows short jobs their own "expressline," thereby giving them isolation from long jobs.…”

Section: B the Advantages Of Sita For High Variabilitymentioning

confidence: 99%

“…By contrast, all other policies described above mix short and long jobs, allowing short jobs to get "stuck" behind long jobs, greatly increasing mean response time. The SITA policy (and its variants) has been part of the common wisdom in some form or other for a long time, and has been the focus of many papers including [18], [12], [11], [23], [8], [19], [6], [22], [10], [3], [1], [9], [5], [20].…”

Section: B the Advantages Of Sita For High Variabilitymentioning

confidence: 99%

“…There are several papers which specifically compare the performance of SITA to LWL [3], [6], [8], [10], [11], [12], [19], [22], [23]. All of these find that as job size variability is increased, SITA becomes far superior to LWL (for low C 2 , SITA may be worse than LWL because not all servers are utilized; however, this behavior changes quickly as C 2 is increased).…”

Section: B the Advantages Of Sita For High Variabilitymentioning

confidence: 99%

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Why segregating short jobs from long jobs under high variability is not always a win

Scheller‐Wolf

Young

2009

2009 47th Annual Allerton Conference on Communication, Control, and Computing (Allerton)

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Abstract-This paper investigates the performance of task assignment policies for server farms as the variability of job sizes (service demands) approaches infinity. The Size-IntervalTask-Assignment policy (SITA), which separates short jobs from long jobs, has long been viewed as the panacea for dealing with high-variability job-size distributions. A very recent paper [16] showed that this common wisdom is flawed: SITA can actually be inferior to the much simpler greedy policy, Least-Work-Left (LWL), for certain common job-size distributions, including many modal, hyperexponential, and Pareto distributions.The above finding leads one to question whether providing isolation for short jobs from long ones is inherently bad, or whether it is just SITA's strict isolation of short jobs that sometimes leads to poor performance. To answer this question, we consider a much more flexible policy, which we call "CycleStealing" (CS). The CS policy is very similar to LWL, in that short jobs can go to any queue, but it still provides short jobs isolation from longs (one server is reserved for short jobs). While CS has many of the same properties as LWL, including high utilization of both servers, we prove, surprisingly, that, for high variability job sizes, CS performs poorly whenever SITA performs poorly. This result suggests that the notion of isolating short jobs from long jobs, under high variability workloads, is sometimes simply not the right thing to do.

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A packet-size aware adaptive routing algorithm for parallel transmission server systems

Oida¹,

Saito²

2004

Journal of Parallel and Distributed Computing

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Characteristics of deterministic optimal routing for a simple traffic control problem

Cited by 7 publications

References 15 publications

Surprising results on task assignment in server farms with high-variability workloads

Surprising results on task assignment in server farms with high-variability workloads

Why segregating short jobs from long jobs under high variability is not always a win

A packet-size aware adaptive routing algorithm for parallel transmission server systems

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