The LogP machine is a model for
parallel computation
Parallel computing is a type of computation in which many calculations or processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different for ...
.
[Culler et al. 1993]
It aims at being more practical than the
PRAM
Pram or PRAM may refer to: a bulbous growth on senior canines, varying in size, usually benign and painless. If it bursts, it will ooze pus and blood.
Places
* Pram, Austria, a municipality in the district of Grieskirchen in the Austrian state of ...
model while still allowing for easy analysis of computation.
The name is not related to the
mathematical logarithmic function: Instead, the machine is described by the four parameters
,
,
and
.
The LogP machine consists of arbitrarily many processing units with
distributed memory
In computer science, distributed memory refers to a multiprocessor computer system in which each processor has its own private memory. Computational tasks can only operate on local data, and if remote data are required, the computational task m ...
.
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.
The machine is described by the four parameters:
*
, the
latency of the communication medium.
*
, the
overhead of sending and receiving a message.
*
, the gap required between two send/receive operations. A more common interpretation of this quantity is as the inverse of the
bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
of a processor-processor communication channel.
*
, the number of processing units.
Each local operation on each machine takes the same time ('unit time'). This time is called a processor cycle. The units of the parameters
,
and
are measured in multiples of processor cycles.
See also
*
Bulk synchronous parallel The bulk synchronous parallel (BSP) abstract computer is a bridging model for designing parallel algorithms. It is similar to the parallel random access machine (PRAM) model, but unlike PRAM, BSP does not take communication and synchronization fo ...
*
Parallel programming model
In computing, a parallel programming model is an abstraction of parallel computer architecture, with which it is convenient to express algorithms and their composition in programs. The value of a programming model can be judged on its ''generality' ...
Notes
References
Educational abstract machines
Theoretical computer science
Models of computation
Parallel computing
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