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EspañolGRANULARITY
:''See also: grain and film grain (disambiguation)
'Granularity' is a measure of the size of the components, or descriptions of components, that make up a system. Granularity is the relative size, scale, level of detail or depth of penetration that characterizes an object or activity. It is the "extent to which a larger entity is subdivided. For example, a yard broken into inches has finer granularity than a yard broken into feet."[1]
Systems of, or description in terms of, large components are called 'coarse-grained', and systems of small components are called 'fine-grained'; here ''coarse'' and ''fine'' are descriptions of the granularity of the system, or the granularity of description of the system.
An example of increasingly fine granularity: a list of nations in the United Nations, a list of all states/provinces in those nations, a list of all counties in those states, etc.
The terms "fine" and "coarse" are used consistently across fields; but the term "granularity" itself is not. For example, in investing, "more granularity" refers to more positions of smaller size, while photographic film that is "more granular" has fewer and larger chemical "grains".
A 'fine-grained' description of a system is a detailed, low-level model of it. A 'coarse-grained' description is a model where some of this fine detail has been smoothed over or averaged out. The replacement of a fine-grained description with a lower-resolution coarse-grained model is called 'coarse graining'. (See for example the view of the second law of thermodynamics in the article ''Maximum entropy thermodynamics'')
==In molecular dynamics==
Coarse graining modelling consists in replacing an atomistic
description of a biological molecule (fine details smoothed
over or averaged out) with a lower-resolution coarse-grained model (CG model).
CG models have been developed for investigating the longer time and length scale
dynamics that are critical to many biological processes, especially with
lipid membranes and proteins
(see this section for more and references).
In parallel computing, granularity means the amount of computation in relation to communication, i.e., the ratio of computation to the amount of communication.
'Fine-grained', or "tightly coupled", parallelism means individual tasks are relatively small in terms of code size and execution time. The data are transferred among processors frequently in amounts of one or a few memory words. 'Coarse-grained', or "loosely coupled", is the opposite: data are communicated infrequently, after larger amounts of computation.
The smaller the granularity, the greater the potential for parallelism and hence speed-up, but the greater the overheads of synchronization and communication. (The last two paragraphs are based on ''FOLDOC''.)
In Reconfigurable Computing and in Supercomputing these terms refer to the data path width. The use of about one bit wide processing elements like the configurable logic blocks (CLBs) in an FPGA is called 'Fine-grained' computing or 'Fine-grained' reconfigurability, whereas using wide data paths, such as, for instance 32 bits wide resources, like microprocessor CPUs or data-stream-driven data path units (DPUs) like in a reconfigurable datapath array (rDPA) is called 'Coarse-grained' computing 'Coarse-grained' reconfigurability.
The ''granularity'' of data refers to the fineness with which data fields are sub-divided. For example, a postal address can be recorded, with ''low granularity'', as one field:
# address = 200 2nd Ave. South #358, St. Petersburg, FL 33701-4313 USA
or with ''high granularity'', as many fields:
# street address = 200 2nd Ave. South #358
# city = St. Petersburg
# postal code = FL 33701-4313
# country = USA
or even higher granularity:
# street number = 200
# street = 2nd Ave. South #358
# city = St. Petersburg
# postal code state = FL
# postal-code-first-part = 33701
# postal-code-second-part = 4313
# country = USA
Higher granularity has overheads for data input and storage, but offers benefits in flexibility of data processing.
In credit portfolio risk modeling, granularity refers to the number of the exposures in the portfolio. The higher the granularity, the more positions are in a credit portfolio, providing a higher degree of size diversification, which in turn reduces concentration risk. This is colloquially known as "not putting all your eggs in one basket".
In photography, granularity is a measure of film grain. It is measured using a particular standard procedure but in general a larger
number means the grains of silver are larger and there are fewer grains in a given area.
At a September 2006 White House press briefing, presidential press secretary Tony Snow responded to a question about an asserted link that had existed between Saddam Hussein and al Qaeda terrorist Abu Musab al-Zarqawi. Snow said that Bush indicated there was "no operational relationship" between Zarqawi and Saddam but added, "we just don’t have that kind of granularity in terms of the relationship. And, therefore, we’re not going to outrun the facts."[2]
{{FootnotesSmall|resize=
★ Granular computing
★ Multiple granularity locking
★ Particle size (geology)
'Granularity' is a measure of the size of the components, or descriptions of components, that make up a system. Granularity is the relative size, scale, level of detail or depth of penetration that characterizes an object or activity. It is the "extent to which a larger entity is subdivided. For example, a yard broken into inches has finer granularity than a yard broken into feet."[1]
Systems of, or description in terms of, large components are called 'coarse-grained', and systems of small components are called 'fine-grained'; here ''coarse'' and ''fine'' are descriptions of the granularity of the system, or the granularity of description of the system.
An example of increasingly fine granularity: a list of nations in the United Nations, a list of all states/provinces in those nations, a list of all counties in those states, etc.
The terms "fine" and "coarse" are used consistently across fields; but the term "granularity" itself is not. For example, in investing, "more granularity" refers to more positions of smaller size, while photographic film that is "more granular" has fewer and larger chemical "grains".
| Contents |
| In physics |
| In computing |
| In Reconfigurable Computing and Supercomputing |
| Data Granularity |
| In credit portfolio risk management |
| In photographic film |
| General examples |
| References |
| See also |
In physics
A 'fine-grained' description of a system is a detailed, low-level model of it. A 'coarse-grained' description is a model where some of this fine detail has been smoothed over or averaged out. The replacement of a fine-grained description with a lower-resolution coarse-grained model is called 'coarse graining'. (See for example the view of the second law of thermodynamics in the article ''Maximum entropy thermodynamics'')
==In molecular dynamics==
Coarse graining modelling consists in replacing an atomistic
description of a biological molecule (fine details smoothed
over or averaged out) with a lower-resolution coarse-grained model (CG model).
CG models have been developed for investigating the longer time and length scale
dynamics that are critical to many biological processes, especially with
lipid membranes and proteins
(see this section for more and references).
In computing
In parallel computing, granularity means the amount of computation in relation to communication, i.e., the ratio of computation to the amount of communication.
'Fine-grained', or "tightly coupled", parallelism means individual tasks are relatively small in terms of code size and execution time. The data are transferred among processors frequently in amounts of one or a few memory words. 'Coarse-grained', or "loosely coupled", is the opposite: data are communicated infrequently, after larger amounts of computation.
The smaller the granularity, the greater the potential for parallelism and hence speed-up, but the greater the overheads of synchronization and communication. (The last two paragraphs are based on ''FOLDOC''.)
In Reconfigurable Computing and Supercomputing
In Reconfigurable Computing and in Supercomputing these terms refer to the data path width. The use of about one bit wide processing elements like the configurable logic blocks (CLBs) in an FPGA is called 'Fine-grained' computing or 'Fine-grained' reconfigurability, whereas using wide data paths, such as, for instance 32 bits wide resources, like microprocessor CPUs or data-stream-driven data path units (DPUs) like in a reconfigurable datapath array (rDPA) is called 'Coarse-grained' computing 'Coarse-grained' reconfigurability.
Data Granularity
The ''granularity'' of data refers to the fineness with which data fields are sub-divided. For example, a postal address can be recorded, with ''low granularity'', as one field:
# address = 200 2nd Ave. South #358, St. Petersburg, FL 33701-4313 USA
or with ''high granularity'', as many fields:
# street address = 200 2nd Ave. South #358
# city = St. Petersburg
# postal code = FL 33701-4313
# country = USA
or even higher granularity:
# street number = 200
# street = 2nd Ave. South #358
# city = St. Petersburg
# postal code state = FL
# postal-code-first-part = 33701
# postal-code-second-part = 4313
# country = USA
Higher granularity has overheads for data input and storage, but offers benefits in flexibility of data processing.
In credit portfolio risk management
In credit portfolio risk modeling, granularity refers to the number of the exposures in the portfolio. The higher the granularity, the more positions are in a credit portfolio, providing a higher degree of size diversification, which in turn reduces concentration risk. This is colloquially known as "not putting all your eggs in one basket".
In photographic film
In photography, granularity is a measure of film grain. It is measured using a particular standard procedure but in general a larger
number means the grains of silver are larger and there are fewer grains in a given area.
General examples
At a September 2006 White House press briefing, presidential press secretary Tony Snow responded to a question about an asserted link that had existed between Saddam Hussein and al Qaeda terrorist Abu Musab al-Zarqawi. Snow said that Bush indicated there was "no operational relationship" between Zarqawi and Saddam but added, "we just don’t have that kind of granularity in terms of the relationship. And, therefore, we’re not going to outrun the facts."[2]
References
{{FootnotesSmall|resize=
See also
★ Granular computing
★ Multiple granularity locking
★ Particle size (geology)
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