WO2001065781A2 - Method and apparatus for high-speed generation of a priority metric for queues - Google Patents
Method and apparatus for high-speed generation of a priority metric for queues Download PDFInfo
- Publication number
- WO2001065781A2 WO2001065781A2 PCT/IL2001/000185 IL0100185W WO0165781A2 WO 2001065781 A2 WO2001065781 A2 WO 2001065781A2 IL 0100185 W IL0100185 W IL 0100185W WO 0165781 A2 WO0165781 A2 WO 0165781A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- queue
- time
- items
- queues
- waiting time
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/50—Queue scheduling
- H04L47/56—Queue scheduling implementing delay-aware scheduling
- H04L47/564—Attaching a deadline to packets, e.g. earliest due date first
- H04L47/566—Deadline varies as a function of time spent in the queue
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/50—Queue scheduling
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/50—Queue scheduling
- H04L47/56—Queue scheduling implementing delay-aware scheduling
- H04L47/562—Attaching a time tag to queues
Definitions
- the present invention relates to queuing systems. More particularly, the invention relates to a method and apparatus for real-time, efficient determination of queue priority in high-speed queuing systems.
- Queuing systems are widespread in technical applications such as communication and computer systems.
- items requiring some sort of service arbitrarily arrive at the system and are grouped to form queues, where they await this service to be rendered by a server.
- Items in the queues are serviced according to a certain discipline, such as First-In-First- Out (FIFO) or Last-In-First-Out (LIFO), with FIFO being the prevalent service discipline.
- FIFO First-In-First- Out
- LIFO Last-In-First-Out
- the goal of most scheduling disciplines is to achieve maximum utilization of system resources (servers) while maintaining at least a desired minimal level for the Quality-of-Service (QoS) experienced by queued items.
- the QoS is usually measured by several main parameters: (1) Mean service delay - the average amount of time that an item is expected to wait from arrival at the queue until it is served. (2) Delay variation - the variation of the delay among items. (3) Mean queue occupancy - the average number of items expected to be in a queue. (4) 'Loss probability' or 'blocking probability' - the probability of an item to arrive at a queue that cannot accommodate it, and thus be 'blocked' or 'lost'.
- PGMs priority-generating mechanisms
- a timer (counter) must be associated with each item in the queue from the moment it arrives until its departure.
- the hardware requirements for the implementation of a system based on such an approach render OIA infeasible for most practical implementations.
- the priority value In order for the priority value to represent accurately the queue's status it must express several queuing parameters such as the occupancy, average waiting time and QoS preference.
- priority determining algorithms should have minimum complexity, in order to necessitate as little hardware as possible, and to complete the calculation in as little time as possible.
- the role of the priority generating mechanism is significant since it constitutes the foundation for the scheduling system, thus directly affecting its performance.
- a method for establishing a queue priority for selecting one queue from at least two queues each containing items to be serviced comprising the steps of:
- EAWT estimated aggregate waiting time
- the present invention is directed to a method for real-time generation of priority values for each of a multiplicity of queues, each containing zero or more items waiting for service.
- One or more servers serve items in each of the queues.
- the invention is further directed to an implementation scheme based on estimating the aggregated waiting time of the items in each queue. Since the mechanism is applied to all queues in a similar manner, the description and analysis may be carried out for a single queue, independent of the structure of the whole queuing system. Using the proposed priority generating mechanism, the system may optimally utilize its resources (i.e. the servers) while complying with QoS requirements.
- the queue priority value is defined as a function combining the estimated aggregate waiting time (EAWT) of items in the queue with a predefined (or slowly changing) parameter assigned to the queue, named 'QoS-class'.
- EAWT estimated aggregate waiting time
- 'QoS-class' a predefined (or slowly changing) parameter assigned to the queue.
- the result encapsulates expressions for queue occupancy, item waiting time and the QoS-class parameter.
- such a technique is based on the assumption that the inter- arrival time is locally stationary or, in other words, that the duration between the respective arrivals of successive items found in the queue at any given time is close to a constant.
- the invention does not require a timer or counter to be associated with each item in the queue.
- the invention is also directed to an apparatus for real-time queue priority generation, comprising circuitry for determining the priority value according to statistical queuing information.
- Fig. 1 is an illustration of a basic FIFO queuing system
- Fig. 2 is a block diagram showing functionally a priority generating mechanism according to a preferred embodiment of the invention
- Fig. 3 is a flowchart of the algorithm underlying the priority generating mechanism shown in Fig. 2.
- Fig.l illustrates a queuing system 10 having one or more queues 11 each employing the First-In-First-Out FIFO queuing discipline, where items 12 arrive at the queue 11 and depart from it upon being served by a server 13.
- the item arrival process is assumed arbitrary.
- the time an item waits until it departs from the queue directly relates to the specific queue service statistics characterizing the system.
- Many scheduling schemes may be applied to determine which queue is to be served by available servers, each scheme directly influencing the item departure statistics. In an effort to provide higher priority to queues with items waiting for service longer than others, a measurement of the aggregate item waiting time is determined.
- a timer (counter) must be assigned to each item in the queue as means of tracking the amount of time by which it is delayed. This, however, is infeasible in many practical situations since a counter per item imposes impracticable hardware requirements, especially when long queues are to be maintained. It is a goal of the invention to provide an estimated metric of the aggregate waiting time of items in the queue using moderate hardware requirements, regardless of queue length. It is common practice in some systems to serve several items in a batch from the same queue whenever a server is assigned to serve the queue. According to the preferred embodiment of the invention, a time slot denotes the duration of time in which a server is assigned to serve a particular queue.
- This duration is measured in units of the period between the occurrence of a periodic event called a clock tick.
- the period between clock ticks may be chosen arbitrarily.
- Clock ticks are usually provided to the system in the form of a periodic clock signal.
- Clock ticks are also used as units for the measurement of the waiting time of items in the queue.
- the duration of a time slot can be fixed or variable, and may be chosen arbitrarily by the queuing system designer. The only limitation imposed on the time slot duration is that a server may not begin to serve the queue during the period of a time slot, nor can a server serving the queue cease to serve it during this period.
- the Estimated Aggregate Waiting Time is computed for a queue priority calculation at the end of each time- slot.
- EAWT is an estimate of the sum of waiting times (from arrival until the moment of calculation), in clock ticks, of all items in the queue.
- At the inter-arrival time of items
- At the inter-arrival time of items
- At the At between the arrival of any two adjacent items in the queue.
- an estimation of the EAWT is achieved by employing the following rules: 1. Let W t represent the EAWT at time t, and n t - the number of items in the queue at time t. Whenever a clock tick occurs, every item in the queue is considered to have waited an additional unit of time, hence:
- the EAWT at the begiiining of the time slot denoted by »-> soil / +/c , allows for calculating the EAWT at the end of the time slot using the EAWT known at its beginning.
- the EAWT is updated as follows:
- TS denotes the duration of the time-slot.
- W t can be combined with the QoS class parameter associated with the queue using any mathematical function such as multiplication, addition, exponentiation etc.
- the differentiation between queues using the QoS class parameter may vary in accordance with the application.
- Fig. 2 is a block diagram showing functionally a priority generating mechanism depicted generally as 20 and comprising an EAWT generator 21 responsive to indications of item arrival and departure and clock ticks for determining the Estimated Aggregate Waiting Time, as described above.
- the EAWT generator 21 is coupled to a Combiner 22, which combines the EAWT with a QoS parameter.
- the combined function is fed to a compander 23, whose output is the desired priority metric.
- Fig. 3 illustrates a flowchart of the algorithm for the priority generating mechanism.
- the (n,k) values may be extracted from a lookup table for gaining speed. This is applied mainly in cases where the assumption n » k » 1 does not necessarily hold.
- Calculation time may be substantially shortened, by making the n » k » 1 assumption, to an addition operation and a division. Multiplying the approximated ratio with the previous EAWT value attains an EAWT update.
- the invention is also directed, though not in a limited way, to an apparatus for generating real-time priority metric for use in queuing systems.
- the apparatus consists of an efficient approximation to the aggregate waiting time of items in FIFO-type queues, where the priority directly relates to the approximate aggregate waiting time and to the number of items in the queue, combined with a QoS-class parameter as described above.
- the apparatus according to the invention may be a suitably programmed computer.
- the invention contemplates a computer program being readable by a computer for executing the method of the invention.
- the invention further contemplates a machine-readable memory tangibly embodying a program of instructions executable by the machine for executing the method of the invention.
- the method and apparatus according to the invention have been described with regard to servicing queues in general, a particular application is in the field of communication networks.
- the method may be used to assign queue priorities in the high-speed, high- capacity packet-scheduling network described in our co-pending Israeli patent application no. 132694 filed on November 1, 1999 and entitled "Method and apparatus for high-speed, high-capacity packet-scheduling supporting quality of service in communications networks.
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2001235953A AU2001235953A1 (en) | 2000-02-28 | 2001-02-28 | Method and apparatus for high-speed generation of a priority metric for queues |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IL13475500A IL134755A0 (en) | 2000-02-28 | 2000-02-28 | Method and apparatus for high-speed generation of a priority metric for queues |
IL134755 | 2000-02-28 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2001065781A2 true WO2001065781A2 (en) | 2001-09-07 |
WO2001065781A3 WO2001065781A3 (en) | 2001-12-13 |
Family
ID=11073878
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IL2001/000185 WO2001065781A2 (en) | 2000-02-28 | 2001-02-28 | Method and apparatus for high-speed generation of a priority metric for queues |
Country Status (4)
Country | Link |
---|---|
US (1) | US20030055938A1 (en) |
AU (1) | AU2001235953A1 (en) |
IL (1) | IL134755A0 (en) |
WO (1) | WO2001065781A2 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007158926A (en) * | 2005-12-07 | 2007-06-21 | Fujitsu Ltd | Message control program, message control apparatus, and message control method |
EP2807567B1 (en) | 2012-01-27 | 2018-03-07 | Marvell World Trade Ltd. | Systems and methods for dynamic priority control |
US11237835B2 (en) * | 2015-03-23 | 2022-02-01 | Middleware, Inc. | System and method for processing data of any external services through API controlled universal computing elements |
US11941462B2 (en) | 2015-03-23 | 2024-03-26 | Middleware, Inc. | System and method for processing data of any external services through API controlled universal computing elements |
US10455445B2 (en) * | 2017-06-22 | 2019-10-22 | Rosemount Aerospace Inc. | Performance optimization for avionic wireless sensor networks |
US11153922B2 (en) | 2019-10-15 | 2021-10-19 | Rosemount Aerospace, Inc. | Directional wireless communications onboard aircraft |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0491367A2 (en) * | 1990-12-19 | 1992-06-24 | Bull HN Information Systems Inc. | A queue managing method for an electronic mail system |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3354689B2 (en) * | 1994-02-28 | 2002-12-09 | 富士通株式会社 | ATM exchange, exchange and switching path setting method thereof |
JP3315588B2 (en) * | 1996-05-16 | 2002-08-19 | 株式会社日立製作所 | ATM switch for traffic flow control |
DE19653118C2 (en) * | 1996-12-19 | 2000-11-23 | Siemens Ag | Method for the optimized transmission of ATM cells over connection sections |
CA2242219A1 (en) * | 1997-10-03 | 1999-04-03 | Newbridge Networks Corporation | Classes of service in an mpoa network |
US6108307A (en) * | 1997-12-12 | 2000-08-22 | Newbridge Networks Corporation | Frame relay priority queses to offer multiple service classes |
US6246691B1 (en) * | 1998-08-14 | 2001-06-12 | Siemens Aktiengesellschaft | Method and circuit configuration for the transmission of message units in message streams of different priority |
US6625122B1 (en) * | 1999-11-24 | 2003-09-23 | Applied Micro Circuits Corporation | Selection of data for network transmission |
-
2000
- 2000-02-28 IL IL13475500A patent/IL134755A0/en unknown
-
2001
- 2001-02-28 AU AU2001235953A patent/AU2001235953A1/en not_active Abandoned
- 2001-02-28 US US10/203,719 patent/US20030055938A1/en not_active Abandoned
- 2001-02-28 WO PCT/IL2001/000185 patent/WO2001065781A2/en active Application Filing
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0491367A2 (en) * | 1990-12-19 | 1992-06-24 | Bull HN Information Systems Inc. | A queue managing method for an electronic mail system |
Non-Patent Citations (1)
Title |
---|
CHANGHWAN OH ET AL: "PRIORITY CONTROL ATM FOR SWITCHING SYSTEMS" IEICE TRANSACTIONS ON COMMUNICATIONS, INSTITUTE OF ELECTRONICS INFORMATION AND COMM. ENG. TOKYO, JP, vol. E75 - B, no. 9, 1 September 1992 (1992-09-01), pages 894-904, XP000321325 ISSN: 0916-8516 * |
Also Published As
Publication number | Publication date |
---|---|
WO2001065781A3 (en) | 2001-12-13 |
AU2001235953A1 (en) | 2001-09-12 |
IL134755A0 (en) | 2001-04-30 |
US20030055938A1 (en) | 2003-03-20 |
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