132 lines
2.4 KiB
Markdown
132 lines
2.4 KiB
Markdown
---
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title: "LogP machine"
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chunk: 1/1
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source: "https://en.wikipedia.org/wiki/LogP_machine"
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category: "reference"
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tags: "science, encyclopedia"
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date_saved: "2026-05-05T11:35:56.848173+00:00"
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instance: "kb-cron"
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---
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The LogP machine is a model for parallel computation.
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It aims at being more practical than the PRAM model while still allowing for easy analysis of computation.
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The name is not related to the mathematical logarithmic function: Instead, the machine is described by the four parameters
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L
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{\displaystyle L}
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,
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o
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{\displaystyle o}
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,
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g
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{\displaystyle g}
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and
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P
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{\displaystyle P}
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.
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The LogP machine consists of arbitrarily many processing units with distributed memory.
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The processing units are connected through an abstract communication medium which allows point-to-point communication. This model is pair-wise synchronous and overall asynchronous.
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The machine is described by the four parameters:
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L
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{\displaystyle L}
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, the latency of the communication medium.
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o
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{\displaystyle o}
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, the overhead of sending and receiving a message.
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g
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{\displaystyle g}
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, the gap required between two send/receive operations. A more common interpretation of this quantity is as the inverse of the bandwidth of a processor-processor communication channel.
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P
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{\displaystyle P}
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, the number of processing units.
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Each local operation on each machine takes the same time ('unit time'). This time is called a processor cycle. The units of the parameters
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L
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{\displaystyle L}
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,
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o
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{\displaystyle o}
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and
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g
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{\displaystyle g}
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are measured in multiples of processor cycles.
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== See also ==
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Bulk synchronous parallel
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Parallel programming model
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== Notes ==
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== References ==
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Culler, David; Karp, Richard; Patterson, David; Sahay, Abhijit; Schauser, Klaus Erik; Santos, Eunice; Subramonian, Ramesh; Von Eicken, Thorsten (July 1993), "LogP: Towards a realistic model of parallel computation", ACM SIGPLAN Notices, 28 (7): 1–12, CiteSeerX 10.1.1.319.7827, doi:10.1145/173284.155333 |