Load balancing (computing): Difference between revisions

Revision as of 17:22, 31 March 2025

Revision as of 12:53, 23 April 2025

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Unlike static load distribution algorithms, dynamic algorithms take into account the current load of each of the computing units (also called nodes) in the system. In this approach, tasks can be moved dynamically from an overloaded node to an underloaded node in order to receive faster processing. While these algorithms are much more complicated to design, they can produce excellent results, in particular, when the execution time varies greatly from one task to another.

Dynamic load balancing architecture can be more [[Modular design|modular]] since it is not mandatory to have a specific node dedicated to the distribution of work. When tasks are uniquely assigned to a processor according to their state at a given moment, it is a unique assignment. If, on the other hand, the tasks can be permanently redistributed according to the state of the system and its evolution, this is called dynamic assignment.<ref>{{cite journal |last1=Alakeel |first1=Ali |title=A Guide to Dynamic Load Balancing in Distributed Computer Systems |journal=International Journal of Computer Science and Network Security (IJCSNS) |date=November 2009 |volume=10 |url=https://www.researchgate.net/publication/268200851}}</ref> Obviously, a load balancing algorithm that requires too much communication in order to reach its decisions runs the risk of slowing down the resolution of the overall problem.

===Hardware architecture===

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[[File:Load_Balancing_divisible_tasks.png|thumb|Load balancing algorithm depending on divisibility of tasks]]

By dividing the tasks in such a way as to give the same amount of computation to each processor, all that remains to be done is to group the results together. Using a [[prefix sum]] algorithm, this division can be calculated in [[logarithmic time]] with respect to the number of processors.{{factcitation needed|date=October 2022}}

If, however, the tasks cannot be subdivided (i.e., they are [[Linearizability|atomic]]), although optimizing task assignment is a difficult problem, it is still possible to approximate a relatively fair distribution of tasks, provided that the size of each of them is much smaller than the total computation performed by each of the nodes.<ref name="Sequential and parallel algorithms"/>

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Many telecommunications companies have multiple routes through their networks or to external networks. They use sophisticated load balancing to shift traffic from one path to another to avoid [[network congestion]] on any particular link, and sometimes to minimize the cost of transit across external networks or improve [[Reliability (computer networking)|network reliability]].

Another way of using load balancing is in [[network monitoring]] activities. Load balancers can be used to split huge data flows into several sub-flows and use several network analyzers, each reading a part of the original data. This is very useful for monitoring fast networks like [[10 Gigabit Ethernet|10GbE]] or STM64, where complex processing of the data may not be possible at [[wire speed]].<ref>{{cite conference | last1=Noormohammadpour | first1=Mohammad | last2=Raghavendra | first2=Cauligi S. | title=IEEE INFOCOM 2018 - IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS) | chapter=Poster abstract: Minimizing flow completion times using adaptive routing over inter-datacenter wide area networks | publisher=IEEE | date=2018 | isbn=978-1-5386-5979-3 | doi=10.1109/INFCOMW.2018.8406853 | doi-access=free | pagepages=1–2| arxiv=1802.09080 }}</ref>

===Data center networks===