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Here is how I have had it explained to me previously (with regard to telephony):
Latency is a measure of the time taken to traverse a space between any given points of transmission including elements of measured resistance eg conversions and codecs etc.
eg Where z-a is the transmission (in order a,b,c,d,e,f,....y,z,) and Point1 is place of Origin and Point2 is place of receipt
Point1 Point2 | | z-a.....................>...............z-a ----------------------------------------- The measure of this period = Latency
Between Point1 and Point2 there may be a number of resistant systems eg relays, hops, codecs, AD/DA conversions etc
Latency in this example is therfore the period taken for a specific point within the transmission (in this example the letter "a" but alternatively any point of the sequence transmitted eg any letter between a and z)to pass Point 1 and be effectively received (in original type state) at Point2.
Latency is easily percieved during live television interviews with persons on the other side of the globe wher the transmission is relayed by satellite.
Rough and ready but I hope this contributes
Phil Wright
This article attempts to define a word-concept by examples. Another way is by formal definition. The reference to the workflow paper provides a formal definition of operational latency. Formal definitions exist for the other types as well. Communication latency also has a formal definition in terms of Propagation delay and Velocity of propagation.
The example involving turning around an aircraft is too long. Most of its surface area does not deal with latency as much as parallelizing workflows. This article will be more useful to engineers (or their aspirants) if examples can be trimmed and formal definitions (or pointers to these definitions) provided. Vonkje 13:56, 28 July 2005 (UTC)
When measuring the performance of a software system, we refer to latency as the time a request spends "on the wire" before getting to the software system. We use the term "response time" to talk about the entire operation from a user's perspective. Martin Fowler discusses this in his book "Patterns of Enterprise Application Architecture" on page 7 - 8. (Fowler is one of the most respected authors in the software field).
I would have to agree that latency refers to the time that an operation is not actively being processed, but rather just being communicated from one point to another.
Also note that the word latent means "dormant" or "inactive". From this perspective, a request is inactive until it reaches the system that is going to process it.
-- Javid Jamae 01:43, 07 Apr 2005 (UTC)
One of the most common usages of 'latency' now is for the time lag after a user initiates an action on a computer. For example, the delay between pressing a button and confirmation that the expected action has been taken.
To me (at least) this kind of latency has become at least as important as 'speed' (bandwidth, processing speeds, etc.)
Maybe there should be a section on it here?
Sam Dutton ( talk) 07:12, 6 September 2008 (UTC)
If we consider latency in general all the above definitions are correct. Latency could be defined as the time required for an arbitrary system to change it state from state A to state B. The important thing is what we define to be states A and B.
We can say that initial state A is just before we send an instruction to CPU and final state B is when instruction is processed. So the whole time from start to finish is latency.
But we can also say that state B is when instruction reaches the CPU and starts executing. Then the latency is only the time spent in communicating the instruction (and data) to CPU.
If we would look even more closely we could see that even this latency or "inaction" is not really an inaction. Still some process of communicating the instruction to the CPU is running and it has its own latency. And so on....
TommoZ
I do not question the definition in the Oxford dictionary which says: latent Pronunciation: /ˈleɪt(ə)nt/
Definition of latent adjective
In comparison to delay delay Pronunciation: /dɪˈleɪ/ Definition of delay verb [with object]
noun
Common Usage & References However as latency is used as professional jargon in engineering as delay in event driven systems. Examples hereof are in the recognized works such as:
Other sources concur to the simple definition of latency as
Latency: A measure of time delay experienced in a real-time system.
Such as:
For anyone who want to repeat this study feel free to recycle my search string: http://scholar.google.co.uk/scholar?start=50&q=definition+of+latency+and+delay&hl=en&as_sdt=0,5 — Preceding unsigned comment added by 3swv7y6543 ( talk • contribs) 14:45, 11 November 2012 (UTC)
![]() | This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Here is how I have had it explained to me previously (with regard to telephony):
Latency is a measure of the time taken to traverse a space between any given points of transmission including elements of measured resistance eg conversions and codecs etc.
eg Where z-a is the transmission (in order a,b,c,d,e,f,....y,z,) and Point1 is place of Origin and Point2 is place of receipt
Point1 Point2 | | z-a.....................>...............z-a ----------------------------------------- The measure of this period = Latency
Between Point1 and Point2 there may be a number of resistant systems eg relays, hops, codecs, AD/DA conversions etc
Latency in this example is therfore the period taken for a specific point within the transmission (in this example the letter "a" but alternatively any point of the sequence transmitted eg any letter between a and z)to pass Point 1 and be effectively received (in original type state) at Point2.
Latency is easily percieved during live television interviews with persons on the other side of the globe wher the transmission is relayed by satellite.
Rough and ready but I hope this contributes
Phil Wright
This article attempts to define a word-concept by examples. Another way is by formal definition. The reference to the workflow paper provides a formal definition of operational latency. Formal definitions exist for the other types as well. Communication latency also has a formal definition in terms of Propagation delay and Velocity of propagation.
The example involving turning around an aircraft is too long. Most of its surface area does not deal with latency as much as parallelizing workflows. This article will be more useful to engineers (or their aspirants) if examples can be trimmed and formal definitions (or pointers to these definitions) provided. Vonkje 13:56, 28 July 2005 (UTC)
When measuring the performance of a software system, we refer to latency as the time a request spends "on the wire" before getting to the software system. We use the term "response time" to talk about the entire operation from a user's perspective. Martin Fowler discusses this in his book "Patterns of Enterprise Application Architecture" on page 7 - 8. (Fowler is one of the most respected authors in the software field).
I would have to agree that latency refers to the time that an operation is not actively being processed, but rather just being communicated from one point to another.
Also note that the word latent means "dormant" or "inactive". From this perspective, a request is inactive until it reaches the system that is going to process it.
-- Javid Jamae 01:43, 07 Apr 2005 (UTC)
One of the most common usages of 'latency' now is for the time lag after a user initiates an action on a computer. For example, the delay between pressing a button and confirmation that the expected action has been taken.
To me (at least) this kind of latency has become at least as important as 'speed' (bandwidth, processing speeds, etc.)
Maybe there should be a section on it here?
Sam Dutton ( talk) 07:12, 6 September 2008 (UTC)
If we consider latency in general all the above definitions are correct. Latency could be defined as the time required for an arbitrary system to change it state from state A to state B. The important thing is what we define to be states A and B.
We can say that initial state A is just before we send an instruction to CPU and final state B is when instruction is processed. So the whole time from start to finish is latency.
But we can also say that state B is when instruction reaches the CPU and starts executing. Then the latency is only the time spent in communicating the instruction (and data) to CPU.
If we would look even more closely we could see that even this latency or "inaction" is not really an inaction. Still some process of communicating the instruction to the CPU is running and it has its own latency. And so on....
TommoZ
I do not question the definition in the Oxford dictionary which says: latent Pronunciation: /ˈleɪt(ə)nt/
Definition of latent adjective
In comparison to delay delay Pronunciation: /dɪˈleɪ/ Definition of delay verb [with object]
noun
Common Usage & References However as latency is used as professional jargon in engineering as delay in event driven systems. Examples hereof are in the recognized works such as:
Other sources concur to the simple definition of latency as
Latency: A measure of time delay experienced in a real-time system.
Such as:
For anyone who want to repeat this study feel free to recycle my search string: http://scholar.google.co.uk/scholar?start=50&q=definition+of+latency+and+delay&hl=en&as_sdt=0,5 — Preceding unsigned comment added by 3swv7y6543 ( talk • contribs) 14:45, 11 November 2012 (UTC)