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Topic: Latency (engineering)

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	Latency Summary
		In the case of cancer, the latency period for a small group of transformed cells to result in a tumor large enough to be detected is usually 10–20 years.
		Latency (engineering), a time delay between the moment something is initiated, and the moment its first effect begins.
		Latency in child sexuality, a psychoanalytic phase, extending from roughly age seven to twelve, during which sexuality is repressed or sublimated (now more commonly called "middle childhood" and "prepubescence").
	www.bookrags.com /Latency (623 words)

	Latency (engineering) - Wikipedia, the free encyclopedia
		Latency is a time delay between the moment something is initiated, and the moment one of its effects begins.
		Latency in a packet-switched network is measured either one-way (the time from the source sending a packet to the destination receiving it), or round-trip (the time from the source sending a packet to the source receiving a response).
		The latency of his trip is the time it takes him to go from his house in England to the hotel he is staying at in New York.
	en.wikipedia.org /wiki/Latency_(engineering) (909 words)

	Latency - Wikipedia, the free encyclopedia
		If an article link referred you here, you might want to go back and fix it to point directly to the intended page.
		Latency (engineering), a time delay between the moment something is initiated, and the moment its first effect begins.
		Latency (child sexuality), a psychoanalytic phase, extending from roughly age seven to twelve, during which sexuality is repressed or sublimated (now more commonly called "middle childhood" and "prepubescence").
	en.wikipedia.org /wiki/Latency (144 words)

	BioMedical Engineering OnLine \| Full text \| The effect of latency on bone lengthening force and bone mineralization: an ...
		The purpose of this study was to investigate the effect of latency on the development of bone lengthening force and bone mineralization during mandible distraction osteogenesis.
		The present study aims to investigate the effect of latency on the force needed to distract bone using internal distractor, to determine the effect of latency on mineralization of the newly formed bone, and to provide new methods to allow measurement of force developed during distraction using a strain gauge mounted to internal distractor device.
		In this study, the effect of latency is investigated by using the strain gauges mounted in the internal distractor device and the regenerated bone is evaluated by ultrastructural and mineral analysis.
	www.biomedical-engineering-online.com /content/5/1/18 (3791 words)

	Encyclopedia: Latency (engineering)
		A geosynchronous orbit is a geocentric orbit that has the same orbital period as the sidereal rotation period of the Earth.
		Classical mechanics is a model of the physics of forces acting upon bodies.
		Categories: Engineering This article is a comparison of latency and bandwidth in telecommunications.
	www.nationmaster.com /encyclopedia/Latency-%28engineering%29 (1307 words)

	Latency: Dictionary definition and more
		The engineering definition of latency is the time a message takes to traverse a system.
		Both latency and throughput have a dramatic effect on the design communications and computing systems, because improvements in one aspect often come at the expense of the other.
		Latencies higher than 100 ms make working with a real time music program non-usable.
	www.encyclopedian.com /la/Latency.html (331 words)

	ProSoundWeb \| Opening Pandora's Box? Latency And Digital Audio
		Latency is delay that occurs in audio systems due to the time it takes for sound to travel from place to place, and/or due to the time it takes for digital components to perform calculations.
		In fact, latencies in the 10 ms to 20 ms range actually have a stabilizing affect on tempo and are thought to be preferred over zero latency.
		Latencies less than approximately 10 ms to 15 ms are not perceived as echoes with in-ear monitors.
	www.prosoundweb.com /sr/tech/live/latency.php (3177 words)

	IDENTIFICATION OF INTERMEDIATE LATENCIES IN TRANSIENT VISUAL EVOKED POTENTIALS
		Latency measure depends on the point at which the latency is calculated and usually the peak presents irregularities, so that interpolation is then required.
		However, intermediate latencies between 100ms and 120ms or between 120ms and 130ms,etc. such as 112,123,145 etc the results shown that the intermediate latency cannot be predicted precisely.
		150 abnormal TVEP with latencies of 120, 140, 160, 180 and 200msec
	www.acadjournal.com /2006/V17/part1/p3 (2925 words)

	Apps Communications,Inc. - Latency
		Latency is the time between the started moment and ending moment of packet transfer.
		The word derives from the fact that during the period of latency the effects of an action are latent, meaning "potential" or "not yet observed".
		Latency in a packet-switched network is measured in two ways; one direction (the time between the source sending the packet to the completion at the destination), or round-trip from the source to the destination and back to the source.
	www.appscorp.net /latency.asp (153 words)

	Engineering server-driven consistency for large scale dynamic web services
		Read latency is primarily determined by the fraction of reads that a client can not serve locally.
		Read latency for consistency misses may be orders of magnitude higher than that for local hits, especially when the network is congested or the server is busy.
		In general, we conclude that although previous studies have examined extreme assumptions for prefetching [26,14], it appears that for this workload, modest amounts of prefetching are desirable for minimizing response time when short volume leases are used, and little prefetching is needed at all for long volume leases.
	www10.org /cdrom/papers/264 (9811 words)

	Improving HTTP Latency (Site not responding. Last check: 2007-10-21)
		Latency caused by client or server slowness, however, can in principle be solved simply by buying a faster computer, or faster disks, or more memory.
		For the local case, long-lived connections without pipelining reduces latency by only about 5% to 15%; this implies that the reduction in round trips is more important that the per-connection overheads.
		Note that for the relatively small transfers associated with the median image size, slow-start latencies cannot account for much of the delay; in these tests, the TCP MSS was 1460 bytes, and traces showed that slow-start did not limit the window size.
	archive.ncsa.uiuc.edu /SDG/IT94/Proceedings/DDay/mogul/HTTPLatency.html (4613 words)

	Real-Time Systems from Processing Graphs
		Latency is the interval between the time when a signal arrives from the external sensor and the time when the processed signal is available to the output device.
		Although system engineers have been unable to analyze the properties of latency and memory requirements in PGM graphs, we have shown that this is not an intrinsic property of the methodology.
		The latency bounds developed in [9] are being used to determine the number of processors and the amount of memory required in the new system for the application to meet its mission requirements.
	cse.unl.edu /~goddard/ProcessingGraphResearch.html (2211 words)

	JINSPIRED JXInsight Insights - Network Latency Overhead
		The customer had suspected that network latency costs were impacting the performance of the remote clients but the test staff were not convinced that the network costs could account for such large differences especially because of the network capacity available.
		The first performance engineering task performed was to create an isolated test environment that could be monitored separately from the user population.
		Once this was done 2 users from local and remote geographical locations logged into the isolated application server and performed the opening of one of the forms that was deemed "terribly" slow when executed remotely.
	www.jinspired.com /products/jxinsight/networklatency.html (780 words)

	Ixia awarded patent for real-time data latency measurement methodology (Site not responding. Last check: 2007-10-21)
		Ixia’s engineers and executives named as inventors on the patent are Joel Weissberger, Mark MacWhirter, Manley Klassen, and Errol Ginsburg, the firm’s founder, president, and CEO.
		Latency is a key factor in performance of business-critical applications, including business management software, voice over IP, virtual private network security, network quality of service, and others.
		Ixia uses its technology to provide real-time latency measurements at wire speeds of up to 10 Gigabits per second, which gives network managers the information they need to better plan their network and optimize performance of their network applications.
	www.manufacturing.net /ctl/index.asp?layout=articlePrint&articleID=CA414699 (347 words)

	Using Latency to Evaluate Interactive System Performance
		In this paper, we propose a set of new techniques for performance measurement in which latency is measured in the context of a workload that is realistic, both in terms of the application used and the rate at which user- initiated events are generated.
		The latencies measured are relatively small for Notepad and reflect both the simplicity of the application and the relatively fast PC that we used for our experiments.
		The cumulative latency graph shows that both versions of Windows NT demonstrate similar performance for the short-latency keystrokes, and the majority of the per formance difference is a result of the ability of NT 4.0 to handle the long-latency events much more efficiently.
	www.eecs.harvard.edu /~vino/perf/osdi_full.html (8468 words)

	[No title] (Site not responding. Last check: 2007-10-21)
		Read latency is the time it takes a microprocessor to read a piece of data into a register in response to a load instruction.
		These results clearly show that latency degrades as the number of system processors is increased and that latency improves as the system's bandwidth--number of memory banks--is increased.
		The cache latency to first data is 20 ns, and with one 3.33-ns processor cycle of wave pipelining, its maximum bandwidth is 915 MB/s.
	www.research.compaq.com /wrl/DECarchives/DTJ/DTJH04/DTJH04SC.TXT (15373 words)

	Embedded.com - Linux scheduler latency
		Latency is really a shorthand term for the phrase latent period, which is defined by webster.com to be 'the interval between stimulus and response'.
		In the context of the Linux kernel, scheduler latency is the time between a wakeup (the stimulus) signaling that an event has occurred and the kernel scheduler getting an opportunity to schedule the thread that is waiting for the wakeup to occur (the response).
		Information from Ingo Molnar is that interrupt latency for recent x86 hardware is on the order of 10µs, while interrupt handler duration is typically tens to at most low-hundreds of microseconds, and scheduling duration is a few microseconds.
	www.embedded.com /story/OEG20020628S0066 (5312 words)

	Performance Measurements of MPLS Traffic Engineering and QoS
		The challenge of traffic engineering is how to make the most effective use of the available bandwidth in a large IP backbone networks, or place the traffic over them so that we can achieve the best performance characteristics from the same IP networks even in the event of congestion.
		Obviously, the round-trip latency dramatically increases for the congested IGP path, while it is minimal for packets traversing the MPLS explicit LSPs.
		The results of the average round-trip latency for both TCP flows are shown in Figure 10.
	www.isoc.org /isoc/conferences/inet/01/CD_proceedings/T43 (5819 words)

	Exploring the Bounds of Web Latency Reduction from Caching and Prefetching
		The last three rows show the percent of latency reduced by the simulated caching proxy, the cache hit ratio and the size of the cache that would be required to hold all cached data.
		To examine the variation of latency reduction across separate events, Figure 5 shows histograms of the percent of latency reduced at each event for passive caching, local prefetching, server-hint based prefetching and server-hint based with unlimited storage caching.
		In the workload studied, 57% of the latency is external latency that can be removed by caching or prefetching; 20% of the latency is external latency that cannot be removed, from events such as first contacts or queries; 23% of the latency appears to be internal latency.
	www.cse.ucsc.edu /~tmk/publications/ideal (4880 words)

	Latency
		Latency is directly related to the spindle speed of the drive and such is influenced solely by the drive's spindle characteristics.
		For reading large continuous blocks of data, latency is a relatively minor factor because it will only happen while waiting to read the first sector of a file.
		The use of cylinder and head skewing on modern drives is intentionally designed to reduce latency considerations when switching between consecutive heads or cylinders on long sequential reads or writes.
	www.pcguide.com /ref/hdd/perf/perf/spec/posLatency-c.html (620 words)

	Engineering and Hosting Adaptive Freshness-Sensitive Web Applications on Data Centers
		However, this is achieved at the expense of overheads due to (a) invalidation of cached dynamic content in the edge caches and (b) synchronization of database replicas in the data center.
		The network latency between the end users and the data center has limited impact to the response time since the network latency is low.
		We also observe that the response time increases at a faster rate with longer network latency; as we can see from the figure, the slope of the plot for the network latency of 1250 ms is much steeper than that for the network latency of 250 ms.
	www2003.org /cdrom/papers/refereed/p161/p161-li.html (8088 words)

	NetworkDesigner.net - All about Network Design
		The term comes from the field of electrical engineering, where bandwidth represents the total distance or range between the highest and lowest signals on the communication channel (band).
		Latency refers generally to delays in processing network data, of which there are several kinds.
		This high latency is due primarily to propagation delay as the request message travels at the speed of light to the distant sattelite station and back to the home network.
	www.networkdesigner.net /bandwidth-latency.htm (754 words)

	TELECOMMUNICATION - Companies, Services, Equipment, Technology, Business
		The art of the telecommunications engineer is to analyse the physical properties of the line or transmission medium, and the statistical properties of the message in order to design the most effective encoding and decoding mechanisms.
		This has important economic implications and engineers will research what defects may be tolerated in the signal yet not affect the viewing or hearing experience too badly.
		One of the roles of the telecommunications engineer is to analyse the physical properties of the line or transmission medium, and the statistical properties of the message in order to design the most effective encoding and decoding mechanisms.
	www.telecommunication.teleactivities.net (1054 words)

	Memory structure and data integrity (Site not responding. Last check: 2007-10-21)
		CAS Latency is the number of clock cycles that occur from the input of a command to the output of data.
		Even though the DDR memory chips both use a CAS latency of 2 cycles, the DDR memory system, with the same basic clock rate, can offer up to twice the effective throughput of the synchronous system as shown in the diagram.
		Latency : The length of time, usually expressed in clock cycles, from when a request to read a memory location has occurred and when the data is actually ready.
	www.supinfo-projects.com /en/2004/mem%5Fcircuits%5F2004/1 (2483 words)

	Proceedings of the Third Symposium on Operating Systems Design and Implementation, February 22-25, 1999, New Orleans, ...
		Thread latency is defined to be the delay from the time at which an ISR signals a waiting thread until the time at which the signaled thread executes the first instruction after the wait is satisfied.
		In the case of interrupt latency, because the driver cannot read the time stamp counter at the instant when the hardware interrupt is asserted, the driver I/O read routine reads the time stamp register and sets a timer to expire in a given number of milliseconds.
		As an example of how detailed latency data can be used to forecast quality of service for multimedia applications and low latency drivers, we present a brief analysis of soft modem quality of service as a function of the size and the number of buffers (and thus, the allowable latency in servicing the buffers).
	www.usenix.org /publications/library/proceedings/osdi99/full_papers/cota/cota_html/cota.html (7875 words)

	The effect of latency on bone lengthening force and bone mineralization: an investigation using strain gauge mounted ...
		The duration of latency has been investigated in experimental study 1516171819202122 to determine the ideal latency period.
		The most central zone of the 0-day latency group, observation of low density of SEM micrograph demonstrated fibrous tissue with some osteoid were scattering × 30.
		The most central zone of 4-day latency group, observation of low density of SEM micrograph demonstrated fibrous tissue with some osteoid were scattering × 400.
	www.biomedical-engineering-online.com /content/xml/1475-925x-5-18.xml (3599 words)

	Circuit Cellar - Digital Library - CCO
		Because the entire frame is stored before any decisions are made, there is a delay (or latency) between the time the frame is received and the time it begins transmission on the appropriate output port.
		The latency varies depending on the length of the frame.
		In addition, the latency of the cut-through method is fixed, because forwarding can always begin as soon as the destination MAC address is received.
	www.circuitcellar.com /library/ccofeature/antonakos0502/9.htm (347 words)

	Embedded.com - Interrupt Latency
		Latency as defined by CPU vendors varies from zero (the processor is ready to handle an interrupt right now) to the max time specified.
		Average latency is just the time accumulated into total_time (normalized to microseconds) divided by the number of times the ISR ran (iterations).
		Very speedy processors may run so much faster than the timer tick rate that they always log latencies of zero (though this may indicate that, for all practical purposes, latencies are short enough to not be significant).
	www.embedded.com /story/OEG20010918S0052 (2111 words)

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