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Introduction
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September 2015 - May 2020
February 2010 - present
Publications
Publications (72)
The paper is dedicated to preliminary results and validation of the distributed solution for causal role attribution in gene network expansion problem. The key ingredients of the solution are the web application based on Shiny framework, RBOINC backend as an interface between R language and BOINC desktop grid framework, and parallel (multicore) imp...
In this paper, we introduce the tabu enhanced hybrid quantum optimization metaheuristic approach useful for optimization problem-solving on a quantum hardware. We address the theoretical convergence of the proposed scheme from the viewpoint of the collisions in the object which stores the tabu states, based on the Ising model. The results of numeri...
В работе предложены подходы к исследованию стохастических моделей вычислительных сетей из персональных компьютеров с помощью многосерверных систем обслуживания с избыточностью. Представлены перспективы и ограничения указанного подхода, а также возможные направления дальнейших исследований.
In this research, a single-server M-class retrial queueing system (orbit queue) with constant retrial rates and Poisson inputs is considered. The main purpose is to construct the upper and lower bounds of the stationary workload in this system expressed via the stationary workloads in the classical M/G/1 systems where the service time has M-compone...
In this paper we suggest the method for performance estimation of a realistic size supercomputer model. To do so, we apply exponential splitting to the generalized semi-Markov process model of a supercomputer and obtain the so-called artificial regeneration points which allows to apply regenerative confidence estimation. Numerical results illustrat...
In this paper we discuss preliminary results of experiments of distributed gene network expansion. As a proof of concept, we use the celebrated PC algorithm together with the novel RBOINC package within R environment, which turns out to be a convenient way of massively parallel numerical experiments conduction. Data parallelism at the distributed c...
In this paper we apply the distributed regenerative estimation of the steady-state performance to the supercomputer queueing model with heavy-tailed distributions. Discrete-event simulation by generalized semi-Markov processes is the key tool for the analysis. Based on extensive numerical simulation used, we illustrate the approach by delivering so...
In this paper we introduce the Tabu Enhanced Hybrid Quantum Optimization metaheuristic approach useful for optimization problem solving on a quantum hardware. We address the theoretical convergence of the proposed scheme from the viewpoint of the collisions in the object which stores the tabu states, based on the Ising model. The results of numeric...
In this paper we study a simultaneous service multiserver system which we call speed-scaling supercomputer, where speed-scaling is used to address the performance/power demand tradeoff. We treat the system by three-level modeling approach, using matrix-analytic method, generalized semi-Markov processes and small-scale technical system as the three...
In this paper we address the transient analysis of a markovian two-server supercomputer model where customers are served by a random number of servers simultaneously. The Markov process, which described the model's evolution, is of quasi-birth-death type. It is shown that, at least under low load conditions, the logarithmic norm method can be used...
We consider a single-server system with energy saving inactive state, non-zero setup, shutoff and hot reserve state. Matrix-analytic method is used to obtain the steady-state performance and average power demand, as well as study the energy-performance tradeoff in explicit way. Numerical results illustrate the model’s properties.KeywordsMatrix-Anal...
The convergence of a recently proposed tabu-enhanced quantum annealing algorithm depends critically on the finiteness of memory of the related stochastic process. We discuss the background of quantum annealing and the convergence issues of the tabu-enhanced algorithm. Given the details of the tabu data structure, the so-called tabu matrix, we consi...
R programming language is commonly used for statistical computing, data science and stochastic simulation. Existing packages for R allow to run parallel code on various parallel architectures, however, the support for distributed (volunteer) computing is rather weak. This article describes a new R package RBOINC that allows to run parallel code on...
In this paper we consider a single server queueing model with under general bulk service rule with infinite upper bound on the batch size which we call group clearance. The arrivals occur according to a batch Markovian point process and the services are generally distributed. The customers arriving after the service initiation cannot enter the ongo...
In this paper, we consider a queuing inventory system with heterogeneous customers of K types arriving according to a marked Markovian arrival process. Each class of customers differs by nature of the service they seek and different priorities are assigned for each class resulting in different levels of inventory admitted to exhaust for customers o...
In this paper we obtain sufficient conditions for the multiclass multiserver model with automata-type transitions to have a product-form type explicit form of the stability criterion. We use the method to obtain stability conditions of an interesting simultaneous service multiserver model describing a supercomputer, both in case of phase-dependent...
We study certain properties of the function space of autocorrelation functions of unit, as well as finite state space Continuous Time Markov Chains (CTMCs). It is shown that under particular conditions, the L p norm of the autocorrelation function of arbitrary finite state space CTMCs is infinite. Several interesting inferences are made for point p...
The paper describes a discrete event simulation model of a Desktop Grid system. Firstly, we present a stochastic model of a volunteer computing project. We then employ the event simulation approach based on the generalized semi-Markov processes to develop a discrete event simulation model. Finally, using the simulation model, we describe a performa...
The effect of site preparation (mixed mounding and removal of the humus layer) under a shelterwood of mixed boreal forest along a forest interior-edge gradient on Norway spruce (Picea abies) seedlings was studied two years after planting. Mounds had a positive effect on root development, ectomycorrhiza formation and the absorption of nitrogen (N) a...
In this paper the simultaneous service multiserver queueing model with a small number of servers is studied. The customer occupies and releases a random number of servers simultaneously. The system admits speed scaling technique: both servers switch the service rate at arrival/departure instants according to randomized asynchronous speed scaling me...
In this paper, motivated by an increasing interest in Cognitive Radio wireless transmission systems, we study a stochastic model of a single node of such a system with underlay transmission and balking. The considered model is essentially a single-server system with an ON–OFF type environment governing the service time intensity and triggering the...
The motivation of mixing distributions in communication/queueing systems modeling is that some input data (e.g., service time in queueing models) may follow several distinct distributions in a single input flow. In this paper, we study the sensitivity of performance measures on proximity of the service time distributions of a multiserver system mod...
In this work, we consider an approximation of the so-called far-end-tail distribution of processes describing quality of service (QoS) performance of queueing systems. This approximation is based on the asymptotic equivalence between the excess distribution over a high threshold and the generalized Pareto distribution, for a wide class of the gover...
The paper deals with simultaneous service multi-server system, where customer occupies a random number of servers. The system also admits speed scaling mechanism by switching speed regimes at arrival/departure instants according to the corresponding transition probability matrices. Stability conditions for Markovian case of such a model were derive...
Queueing-inventory models have many practical applications and have been studied extensively in the literature. Most of the studies focus on models in which the the demands occur singly. Only a very few papers analyze models wherein the demands occur in batches. In this paper we consider batch demands in the context of two models, both of which ass...
In this work, we discuss various (stochastic) orderings between random variables, with focus on the failure rate comparison. Then these results are applied to construct a coupling of random variables. In particular, it is shown how to compare the failure rates of various distributions, including Exponential, Weibull, Pareto and Burr distributions....
A common approach to performance estimation of queueing system models is based on point estimators. Confidence intervals provide more insight on the system performance, and basically a regenerative structure of the studied process is required. However, classical regeneration epochs (arrivals into empty system) are too rare (or even might not exist)...
Exponential growth of the amount of data stored worldwide together with high level of data redundancy motivates the active development of data deduplication techniques. The overall increasing popularity of solid-state drives (SSDs) as primary storage devices forces the adaptation of deduplication techniques to technical peculiarities of this type o...
In this paper, we consider a single-server retrial model with multiple classes of customers. Arrival of customers follow independent Poisson rule. A new customer, facing a busy server upon his arrival, may join the corresponding (class-dependent) orbit queue with a class-dependent probability, or leaves the system forever (balks). The orbit queues...
We give a simple proof of the well-known property PASTA for the workload and queue size process in the queueing systems with Poisson input. The proof is based on a relation connecting the workload process at an arbitrary instants and the arrival instants of the customers and, in particular, yields famous Pollaczeck-Khintchine equality. It is then s...
We present regeneration techniques for perfomance estimation of multiserver system characteristics. Providing a necessary background of classical and weak regeneration notions, we focus on less well-known and mainly new construction of artificial classical regeneration, as well as recent method of regenerative envelopes for modeling modern energy e...
In this research paper we consider the matrix polynomial equation arising naturally in the equilibrium analysis of a structured G∕M∕1-type Markov process. We obtain an explicit expression for the unknown rate matrix R being 2 × 2 matrix. The method is based on symbolic solution of the determinantal polynomial equation. Using Cayley–Hamilton theorem...
Cloud computing is continuing to prove its flexibility and versatility in helping industries and businesses as well as academia as a way of providing needed computing capacity. As an important alternative to cloud computing, desktop grids allow to utilize the idle computer resources of an enterprise/community by means of distributed computing syste...
Presentation of the result at DCCN 2017 conference
A stochastic model of a multiserver queueing system with simultaneous service of a customer by a random number of servers and threshold-based (hysteretic) control of the service rate is presented. The performance and quality-of-service measures of the model are defined. Numerical results of experiments studying the dependence of performance/energy...
In this paper, we study a multiserver system in which each customer requires a random number of servers simultaneously and a random but identical service time at all occupied servers. This model describes the dynamics of modern high performance clusters. Stability criteria of this system (under exponential assumptions) have been proved earlier for...
In this paper, we study the stability conditions of the multiserver system in which each customer requires a random number of servers simultaneously and a random service time, identical at all occupied servers. We call it cluster model since it describes the dynamics of the modern multicore high performance clusters (HPC). Stability criterion of an...
In this paper, we consider a model of communication system with state-dependent service rate. This mechanism allows to change service rate to increase the efficiency of the system. Motivation of such a system is discussed as well. Then we present the regenerative proof of the sufficient stability conditions of the system which is based on the negat...
In this paper we develop a novel approach to confidence estimation of the stationary measures in high performance multiserver queueing systems. This approach is based on construction of the two processes which are, respectively, upper and lower (stochastic) bounds for the trajectories of the basic queue size process in the original system. The main...
We continue to develop a novel approach for confidence estimation of the stationary measures in the model describing high performance multiserver queueing systems, such as high performance clusters (HPC). We call this model cluster model. This model is described by a stochastic process, and in the framework of the approach, we construct two envelop...
We propose a new approach which allows to accelerate verification of the stability criterion of a multiserver
model with simultaneous service for large number of servers. This approach reduces a state space related to calculation of a basic normalization constant included in the stability condition. Moreover, this result allows to obtain a stable c...
In this paper, we consider
a state-dependent mechanism
which can be used to reduce mean power consumption in modern communication and computer systems. This mechanism allows to change flexibly the service rate so as to increase the energy efficiency of the system. We focus on computer systems with sojourn time dependent service rate, and present a...
The workload model of a high-performance cluster is considered in the context of an upgrade (increase the computational power) or downgrade (save energy) problems. Analytical solutions are found that provide stochastic stability of the workload. The results of numerical experiments with log-files of a real workload are presented.
Some recent results presented at Aalto University, including the stability criterion and it’s accelerated version, exact solution for a single-server green computing model, some tasks in the volunteer computing research
A multiserver model with simultaneous service as a model of a high performance computing cluster is viewed. The stability criterion of the model under the assumptions of i. i. d. exponentially distributed driving sequences is considered. The condition is applied to the problem of optimal task deadline selection. Simulation results are presented, th...
A multi-server model with simultaneous service and
concurrent server release is considered. A stability condition
of the model (under exponential assumptions) is presented. A
method for fast evaluation of the stability criterion is obtained.
The condition allows to verify the stability of a supercomputer
at design time, provided that the governing...
We give a short survey of the moment properties of the basic regenerative queueing processes. Moreover, we show applicability of the regenerative simulation to estimate a steady-state performance measure of the positive recurrent basic process possessing long-range dependence. The moment properties of the embedded renewal process of regenerations p...