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Topic: Elevator algorithm

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	[No title]
		Suppose the elevator is on the third floor, and inside the elevator the "gound" and "basement" buttons are pressed.
		Elevator B is also going up (a few seconds behind elevator A) and will stop on the 4nd and 6th.
		Suppose there is only one elevator car, and that it runs on the standard algorithm, and that all elevator journeys have the ground floor as either starting point or destination (a reasonable assumption).
	www.math.niu.edu /~rusin/known-math/94/elevators (1348 words)

	Elevator - Wikipedia, the free encyclopedia
		Elevators are not an acceptable means of escape during a fire and should not be used by the Public for this purpose.
		Freight elevators are generally required to display a written notice in the car that the use by passengers is prohibited, though certain freight elevators allow dual use through the use of an inconspicuous riser.
		The elevator in the new city hall in Hannover, Germany is a technical rarity, and unique in Europe, as the elevator starts straight up, but then changes its angle by 15 degrees to follow the contour of the dome of the new city hall in Hannover.
	en.wikipedia.org /wiki/Elevator (5197 words)

	Elevator - free-definition (Site not responding. Last check: 2007-10-18)
		An elevator consists of a cab (also "cage" or "car") or platform, the ropes or cables required to raise and lower it using pulleys, and machinery to move the rope.
		In 1853, Elisha Otis introduced the safety elevator, which prevented the fall of the cab if the cable broke, and on March 23, 1857 his first elevator was installed at 488 Broadway in New York City.
		The elevator in the new city hall in Hannover is a technical rarity, and unique in Europe, as the elevator starts straight up, but then changes its angle by 15 degrees to follow the contour of the dome of the new city hall in Hannover.
	www.free-definition.com /Elevator.html (1248 words)

	AI Magazine: An AI-based approach to destination control in elevators - Articles (Site not responding. Last check: 2007-10-18)
		Like many other industries, the elevator industry is currently facing two main challenges: First, the continuous pressure to lower construction costs of buildings requires that the core space occupied by an elevator installation be reduced and that transportation performance be significantly improved.
		Most of the physical components of an elevator, for example, drives and shaft installations, are invisible to the passenger and can be exchanged without even being noticed, but the available services and their quality determine how an elevator installation is perceived by the customer.
		Two main criteria are used to evaluate an elevator control algorithm: First, the so-called HC5% value specifies the handling capacity of a group of cars within five minutes in terms of the percentage of the building population that is served.
	www.findarticles.com /p/articles/mi_m2483/is_3_23/ai_92806026 (1402 words)

	[No title]
		Most Linux block device drivers use a generic tunable "elevator" algorithm for scheduling block I/O. The /sbin/elvtune program can be used to trade off between throughput and latency.
		Changes to the elevator settings for a partition will apply to the elevator for the device the partition is on; all partitions on a device share the same elevator.
		Once you have found elvtune settings that give you your most satisfactory mix of latency and throughput for your application set, you can add the calls to the /sbin/elvtune program to the end of your /etc/rc.d/rc.local script so that they are set again to your chosen values at every boot.
	www.redhat.com /support/wpapers/redhat/ext3/tuning.html (833 words)

	[No title] (Site not responding. Last check: 2007-10-18)
		Clarified that ``callElevator...should not return until a non-full elevator reaches that floor'' means that the elevator should not be full when callElevator checks to see if an elevator has arrived; it's OK if it becomes full after the check and before callElevator returns.
		A scheduling algorithm is an infinite loop that services the floor it is on, decides which floor the elevator should go to next, and then goes to that floor.
		In the advanced algorithm, an elevator determines which direction to move based on the persons it needs to drop off and the floors at which persons have requested an elevator.
	www.cs.umd.edu /class/spring2004/cmsc433/p4 (2470 words)

	Elevator (Site not responding. Last check: 2007-10-18)
		Other locations have elevators that are located along the outside wall of buildings.
		This allows the elevator system to place cabs where they are most needed, and allow for the smooth running of the system.
		Cable/traction Elevators - Operate using a counterweight that allows the elevator to easily be pulled up or down using cables attached to the roof of the elevator car.
	www.yotor.com /wiki/en/el/Elevator.htm (1333 words)

	Elevator algorithm@Everything2.com
		One of the critical parts of the elevator algorithm is its simplicity and the speed at which decisions are made.
		An efficient elevator system is actually very complicated, and was the basis of the game Sim Tower by Maxis (the manual mentions some of this).
		There are special considerations with elevator systems that go beyond the simple elevator algorithm, such as the arrangment of express elevators, number of elevators present, peak usage and off-peak usage patterns, etc.
	everything2.com /index.pl?node_id=815179 (903 words)

	[No title]
		Elevator Scheduler ------------------ Your task is to implement part of an elevator simulation and to gather some statistics about it.
		Your algorithm must cause an elevator to become idle if it arrives at a floor and there are no outstanding requests.
		Write down a description of your elevator algorithm, since that will clarify your ideas and will be included later in your report, anyway.
	www.dgp.toronto.edu /people/JamesStewart/270/9697f/hwk3/hwk3.txt (1106 words)

	The Elevator Simulator Java Programming Challenge for Elevator Control
		The elevator challenge is an elevator simulator educational resource that allows users to practice their programming skills in developing an algorithm to control a group of elevators/lifts in different building scenarios.
		The goal of the Elevator Challenge is to provide students and hobbyists a chance to practice their programming skills by addressing a real-life problem - how to most efficiently control the elevators or lifts of a building.
		About Me The elevator challenge was born out of a long time curiosity in the control of elevators, especially after spending extended periods waiting in the lobby of office buildings and hotels.
	www.elevatorchallenge.com (324 words)

	LWN - Kernel
		These algorithms have traditionally worked by keeping the disk head moving in the same direction for as long as possible, in a way similar to the way normal building elevators work.
		The first is that the system currently does not use a pure elevator; it will put requests with a low sector number at the top of the queue regardless of the current head position.
		The longer-term plan is clearly to make it possible to plug in different elevator algorithms entirely, but that has not been implemented at this point.
	lwn.net /2000/1123/kernel.php3 (1263 words)

	CS 1538 Introduction to Simulation (Site not responding. Last check: 2007-10-18)
		Modern elevators are sophisticated machines with computerized controls and their behavior is typically managed by computer algorithms, whether they be simple or complex.
		Average wait time for a passenger from the time he / she arrives at the elevator area until he / she gets on the elevator.
		The results you obtained for each of your algorithms, and a comparison of the results between the two different algorithms.
	www.cs.pitt.edu /~ramirez/cs1538/assigs/assig3.html (1762 words)

	LWN - Kernel
		These algorithms have traditionally worked by keeping the disk head moving in the same direction for as long as possible, in a way similar to the way normal building elevators work.
		The first is that the system currently does not use a pure elevator; it will put requests with a low sector number at the top of the queue regardless of the current head position.
		The longer-term plan is clearly to make it possible to plug in different elevator algorithms entirely, but that has not been implemented at this point.
	old.lwn.net /2000/1123/kernel.php3 (1263 words)

	collision detection: A new elevator algorithm
		A few months ago, I blogged about a neat elevator hack that allows you to commandeer an elevator and go directly to your floor, without waiting for others.
		Now Fujitec America Inc. -- an elevator company whose tagline is "The Art and Science of Moving People" --has developed a technique that is both more ethical and more mathematically interesting: An algorithm that eases elevator bottlenecks by intelligently grouping passengers based on their destination.
		Also, from my university days I seem to remmember that the simplest disk access algorithms are very similar to elevator algorithms with each elevator being a drive head, and the floors being the data's location on the disk.
	www.collisiondetection.net /mt/archives/2006/01/_a_few_months_a.html (1224 words)

	Linux Block Device Architecture
		The elevator algorithm decides whether the buffer_head can be merged with an existing request (provided that the request remains contiguous).
		The elevator algorithm can suggest a request object after which the new request object can be inserted (so that when the queue is processed, the sectors are in a proper order), otherwise the new request object is added at the end of the queue.
		If a request object is 'suggested' by the algorithm but that is not adjacent to the buffer, the newly created request object will be added 'near' the suggested request object (i.e., front/back based on the return value of the algorithm).
	www.geocities.com /ravikiran_uvs/articles/blkdevarch.html (4546 words)

	Perl.com: Going Up?
		At the end of the simulation, the user receives a report showing the efficiency of the elevator algorithm based on the waiting and riding time of the passengers.
		Since the elevator threads are in an infinite loop the main thread needs a way to tell them when the simulation is over.
		Elevators simply travel from floor to floor opening and closing doors in response to buttons being pushed by people.
	www.perl.com /lpt/a/2002/09/04/threads.html (3525 words)

	environment variable (Site not responding. Last check: 2007-10-18)
		The elevator algorithm is a disk scheduling algorithm where the disk head moves like an elevator in the building.
		An encryption key is a number that is the input to an encryption algorithm and is used to encode a plain-text message into a cipher-text message.
		External fragmentation happens when a dynamic memory allocation algorithm allocates some memory and a small piece is left over that cannot be effectively used.
	axp.missouri.edu /cecs352/GLOSS/ge.htm (401 words)

	Elevator - Enpsychlopedia (Site not responding. Last check: 2007-10-18)
		These machines are generally the best option for basement or overhead traction use for speeds up to 350 ft/min.
		In one design (http://www.otis.com/products/detail/0,1355,CLI1_PRD735_PRT30_PST46_RES1,00.html) manufactured by Otis, the cab is lifted by a pair of hydraulic jacks, one on each side of the elevator.
		Elevator Moods (http://www.elevatormoods.com)-Fictional security films of elevator passengers.
	www.grohol.com /wiki/Elevator (5136 words)

	HW #1 (Site not responding. Last check: 2007-10-18)
		Suppose each I/O request asks for one block of data, and the start position of the disk arm is at the inner-most track of the disk.
		Part 2 (10 points): Assuming that the disk controller is using the first come first serve algorithm instead, recompute the parameters in Part 1.
		Name one possible improvement to the elevator algorithm, and show your reasoning.
	www-db.stanford.edu /~ullman/dbsi/sum99/handouts/hw1.html (496 words)

	Linux-Kernel Archive: By Thread
		Re: (reiserfs) Re: An elevator algorithm Xuan Baldauf
		Re: (reiserfs) Re: An elevator algorithm Hans Reiser
		Re: (reiserfs) Re: An elevator algorithm (patch) Jens Axboe
	www.uwsg.indiana.edu /hypermail/linux/kernel/0009.2 (3805 words)

	Untitled
		floors move passengers on and off elevators and move them from one list to another, then passenger creation/destruction is just a special case of passenger management for the first floor.
		A truly general elevator algorithm, one that never makes unnecessary motion, one that never leaves passengers stranded, one that doesn't pick up passengers going the wrong way for its motion, one that stops when it has no destinations, such an algorithm is complicated and very error prone.
		Adopt a simple, inefficient algorithm that will guaranteed coverage of all floors and eventual service of all passengers.
	courses.dce.harvard.edu /~cscie225/fall97/HW5.HTM (1019 words)

	COM 1330 Operating Systems (Site not responding. Last check: 2007-10-18)
		The disk drive is reading some sectors on cylinder 22 when the sequence of requests arrives.
		(This is only used in the Elevator algorithm where it determines the initial direction.) Show the order in which the cylinders are accessed, and show how long the disk drive takes to perform the seek to get to each cylinder.
		Show only the seek times and the total seek time for each algorithm.
	www.ccs.neu.edu /home/kenb/1330/finans.html (620 words)

	[No title] (Site not responding. Last check: 2007-10-18)
		A personal computer salesman visiting Brandeis remarked during his sales pitch that his company had devoted substantial effort to making their version of Unix very fast.
		As an example, he noted that their disk driver used the elevator algorithm and also queued multiple requests within a cylinder in sector order.
		A student, Harry Hacker, was impressed and bought one.
	www.cs.brandeis.edu /~mfc/cs31a/ps6.html (187 words)

	LKML: Gong Su: Re: Linux 2.4.x block device driver question
		I actually disabled the elevator algorithm by substituting in my own elevator_noop_merge function that simply always returns ELEVATOR_NO_MERGE.
		So each request will only have one buffer_head hanging off it (unless my naive idea of disabling the elevator algorithm didn't work?).
		It helped to prolong the life of the machine a little more but the machine still died eventually.
	lkml.org /lkml/2003/6/2/30 (210 words)

	[No title]
		The first is Shortest // Seek First and the latter is known as the Elevator algorithm.
		> algorithm; break; case 4: strcpy(input_file, argv[1]); cylinder = atoi(argv[2]); seek_time = atoi(argv[3]); cout
		> algorithm; break; case 5: strcpy(input_file, argv[1]); cylinder = atoi(argv[2]); seek_time = atoi(argv[3]); algorithm = argv[4]; break; default: cout << "Incorrect number of arguments!"; exit(1); } make_list(input_file, algorithm*, cylinder, seek_time); // now the next step return; }
	www.cs.uml.edu /~klippe/disk.txt (192 words)

	Linux-Kernel Archive by thread
		Re: linux-kernel-digest V1 #2824 (was: elevator) Jamie Lokier
		Re: [OFFTOPIC] Re: elevator algorithm bug in ll_rw_blk.c Alex P. Madarasz, Jr.
		Re: elevator algorithm considered irrelevant Rik van Riel
	www.ussg.iu.edu /hypermail/linux/kernel/9811.2 (5347 words)

	[No title] (Site not responding. Last check: 2007-10-18)
		Subject: Question about the elevator algorithm > I was wondering if you'd be able to further explain the implementation of the > Request buffer of the DiskDriver class.
		It is no longer in the the pending request buffer, but it is not yet completed (at least not until the processing is completed).
		> Also, concerning the elevator algorithm, is the DiskDriver thread supposed to > loop over all Requests in the current direction, and only change direction if > there's no Request's requiring a greater or equal cylinder up, and vice versa > for down?
	www.ccs.neu.edu /home/kenb/com1330/news/66 (176 words)

	Linux.com - Shall I explain elevator algorithm (+sawtooth etc)
		Linux.com - Shall I explain elevator algorithm (+sawtooth etc)
		I just wrote a response about it to the kernel list, so would a discussion of the elevator algorithm, and sawtooth algorithm (plus mention of minimum movement) be appreciated if I get it checked over by `someone who knows?'
		NewsForge --online technology news on Open Source, Linux and IT.
	www.linux.com /guides/khg/HyperNews/get/devices/block/2.shtml (150 words)

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