SU1714614A1 - Device for simulating queueing systems - Google Patents

Abstract

The invention relates to specialized electronic modeling tools and is intended to investigate queuing systems. The purpose of the invention is to expand the scope of application of the simulation of cyclic reception request cycling, from service queues. The device contains a block of random-pulse generators. blocks of counters, blocks of elements I. OR. prohibition, block of reversible queue length counters, reversible counter of occupied channels, elements AND, OR, prohibition. New in the device is a block of analysis of the queue and the second block of elements I. 2 Il.

Description

The invention relates to specialized electronic modeling tools for the investigation of queuing systems.

A device for simulating a QS containing a logic unit, an input flow generator, a control unit, a clock pulse generator, counters, a measurement unit of 1 time of service channel occupancy is known.

The disadvantage of this device is the low accuracy of the simulation.

 Closest to the proposed technical solution is a device for simulating QS. containing low priority rate generator, high priority rate generator, high and low priority rate meters, high and low priority rate failure counters, five aanpieTa elements, nine AND elements, five OR elements, reversible counter channels, high priority queue reversible queue counter, low priority reversible queue counter, random time delay block.

The disadvantage of this device is. that it does not allow to simulate the QS with the cyclic discipline of receiving from the queue to service;

The purpose of the invention is to expand the range of application of the device by simulating a cyclic discipline of taking a quota from the queue to service.

The main idea of this discipline is service. that from a non-uniform flow, requisitions are organized to queues (k is the number of requisitions types), each of which is assigned a priority. Applications with a higher priority do not interrupt service for low-priority applications. After the completion of the service of any application, the queue priorities are changed in a round robin so that the last served queue has the lowest priority, the next highest priority and then in a circle in order to kill the priority. Such a service discipline is characteristic of systems in which the queues have the same priority and cannot be preferred.

To achieve this goal, a device for simulating queuing systems, containing a block of random pulse generators, a block of incoming quotes, a block of unserved queuing meters, a block of reversing queue length counters, a reversing busy counter, three elements OR, And , two groups of elements And, the first block of elements And, two elements of the prohibition, a block of random timesHbik delays, a group of elements of the ban, the outputs of the block of random-pulse generators of the order are connected It is possible to count the inputs of the block of incoming order counters, the first inputs of the elements of the first group and the information inputs of the elements of the prohibition group whose control inputs are combined with the second inputs of the same elements of the first group and connected respectively to the outputs of the elements of the second group, the outputs of the elements of the first the groups are connected to the corresponding inputs of the block of unserved servicing counters, the outputs of the prohibition elements of the group are connected respectively to the inputs of the first OR element and to the information inputs of the first About the block of elements And whose outputs are connected respectively to the summing inputs of the block of the reversing queue length counters, the bit outputs of the reversing counters of which are connected respectively to the inputs of the elements AND of the second group, the output of the first element OR is connected to the information input of the first prohibition element whose output is connected to the summing input reversible counter of occupied channels, the bit outputs of which are connected respectively to the inputs of the element I, the output of which is connected to the control input of the first And the control input of the first prohibition element, the output of the second element OR is connected to the control input of the second prohibition element, the output of which is connected to the subtractive input of the reversing counter of occupied channels, the block of prohibition elements, two blocks of OR elements, the second block AND elements and a queue analysis block consisting of two AND groups, a group of NOT elements and a group of OR elements; moreover, in the queue analysis block, the output of each OR element of the group is connected to the first inputs of the corresponding And the constituent elements of the first and second groups, and the outputs of NOT elements connected respectively with the group

the second inputs of the elements of the second group, the output of the K-th element of the second group (K 1, N-1) is connected to the first input of the (K + 1) -th element of the OR group, and the output of the N-ro element of the second group is connected to the first input the first element OR of the group, the outputs of the elements AND the first group of the block of analysis of the queue are connected respectively to the subtractive inputs of the block of the reverse queue length counters and to the inputs of the first

5 groups of the first block of OR elements, the inputs of the second group of which are connected respectively to the outputs of the prohibition block, the control input of which is connected to the output of the AND element, and the information inputs of the block of prohibition elements are connected respectively to the outputs of the prohibition elements of the group, the outputs of the first block of OR elements are connected correspondingly, with random block inputs

5 time delays, the outputs of which are connected respectively to the information inputs of the second block of AND elements and the inputs of the third OR element, the output of which is connected to the information input

0 of the second prohibition element, the bit outputs of the reversible counters of the block of reversible counters of the queue length are connected respectively to the inputs of the second block of OR elements, the outputs of which are connected respectively to the inputs of the elements of the NOT group and the second inputs of the AND elements of the first group of the queue analysis unit and the inputs of the second element OR, output which is connected to the control input of the second

0 of the AND block, the K-th output of which is connected to the second input (K + 1) of the-th OR element of the group of the analysis queue block, and the N-th output of the second block of AND elements connected to the second input of the first OR element

5 groups of the block of the analysis of queue.

Thus, in order to expand the field of application of the device by simulating a cyclic discipline

0 a block of prohibition elements, two blocks of OR elements, a second block of AND elements, a block of queue analysis consisting of two groups of AND elements, a group of NOT elements and a group of OR elements are added to it.

. Figure 1 shows the scheme of the proposed device; figure 2 - block diagram of the analysis.

The device contains a block of 1 random-pulse-voltage generators, block 5

incoming counters, block 6 counters of unattended requests, block 19 reversible queue length counters, reversible, counter 10 occupied channels, first 4, second 21 and third 8 OR elements, element 11, first 3 and second 17 groups of elements AND , the first 16 and second 18 blocks of elements And, the first 15 and second 9 elements of the ban, block 7 of occasional time delays, a group of 2 elements of the ban, block 14 of the elements of the ban, the first 12 and second 13 blocks of elements OR, block 20 analysis of the queue, consisting from the first 23 and second 24 groups of elements And, a group of 25 elements H and groups of 26 or.

The device works as follows.

When at least one channel is free in the system, the signal from the output of the AND 11 oTcyt element is present, and the pulses from block 1 of the random time interval generators through the open prohibition elements of group 2, the OR 4 element and the open prohibition element 15 arrive at the summing input of the counter 10 of the number occupied channels, increasing its code by one, which means the occupation of one channel. In addition, pulses from the outputs of the prohibition elements of group 2 through the open prohibition elements of block 14 and block 12 of the elements OR arrive at the corresponding input of the flare 7 LINES of random time delays, which simulates the process of servicing a non-uniform flow of demand. A pulse from a block of 7 random time delay lines, which appeared on one of its outputs after a time equal to a random service duration. An appropriate type of signal, through the element OR 8, the open prohibition element 9 enters the subtracting input of the counter 10 of the number of occupied channels and writes off from it a unit, thereby simulating the destruction of one channel. At the moment of time when all the channels are occupied, a signal arrives at the output of element 11 and arrives at the control inputs of block 16 of elements AND, prohibition elements of block 14 and element 15.that the AND unit 16 otkr1vayuts elements prohibition unit 14 and the element 15 are closed and the pulses from the generator unit 1 is passed to the respective inputs of the summing block 19 reversible counters of applications are in the queue for simulating setting wok acc favoring queue,

In the case when the queues are not empty, signals are present at the output of the corresponding OR elements of block 13 and at the output of the OR element 21; Last closes

the prohibition element 9 prohibits the passage of 1e pulses from the output of the element OR 8 to the subtracting input of the reversible counter 10 (since the service channels should not be released) and opens the elements AND block 18, allowing the passage of signals from the outputs of the block 7 random time delays to the information inputs of the block 20 analysis.

0 The signals from the output of the elements OR of the block 13 are fed to the corresponding control inputs of the analysis block 20. In this case, the latter ensures the selection of the highest priority non-empty queue, which is accompanied by the appearance of a signal at the corresponding output of the analysis unit. This signal arrives at the subtractive input of the corresponding reversible counter of block 19, writing off a unit from it, and simultaneously

0 through the corresponding element OR of block 12 - to the corresponding input of block 7, imitating the receipt of the application from the highest priority service queue.

5 At the moment when all the places of any queue are occupied, the output of the corresponding AND element of group 17 is a signal arriving at the control inputs of the corresponding elements.

0 prohibition of group 2 and element AND of group 3. At the same time, the element of prohibition of group 2 is closed, the element AND of group 3 is opened, and the pulses from block 1 of the generators pass through the element AND of group 3, imitating the flow

5 for rejected service. The number of such applications of each type is counted by the corresponding counter of block 6. The analysis block 20 operates as follows .;

0. The presence of the application in the corresponding queue ensures the presence of a signal at the control input Yi of the corresponding channel 22 of the analysis unit. This signal opens the element of And Group 23 and through the element

5 NOT group 25 closes the AND element of the group 24. An impulse from the information “move Ui arrives at the OR element of the 260 + 1) -th channel element. Depending on which of the AND elements of groups 23 and 24 is open (which is determined by the presence or absence of applications in this queue), the signal from the output of the OR element of group 26 passes either to the output of the analysis block (AND element of group 23) or through the element AND group 24 to the second

5 input element OR group 26 of the next channel, etc. Thus, the last served queue has the lowest priority, the next is the highest priority and then in a circle in order of decreasing priority. This effect is achieved by the indicated

connections of information inputs of the analysis block and interchannel links in the analysis block.

The correspondence of the types of inhomogeneous flow is achieved in the following way. The number of random pulse generators of the application in block 1 (and hence the number of outputs of this unit) is equal to the number of types of application flows, i.e. Each generator generates pulses imitating the receipt of a quota of the same type.

The number X of channel elements of random time delays in block 7 is also equal to the number of types of applications serviced (X is the number of service channels). Each element of this block simulates servicing applications of the same type and can be performed according to the scheme shown in Fig.2. Thus, the connection of the outputs of block 1 of the generators through the corresponding prohibition elements of group 2, block 14 and the elements of OR block 12 with the corresponding inputs of block 7 makes it possible to achieve a simulation of the service of each type of request in its element of the random time delay. For counting the number of applications in each queue, a separate reversible counter is used from the components of block 19. The bit outputs of each counter are connected to the inputs of the corresponding AND element of group 17 and the corresponding OR element of block 13.

By adjusting the generators of block 1 and the elements of block 7, it is possible to vary the parameters of the simulated process for servicing a heterogeneous flow of applications with a cyclic discipline for receiving applications from a queue.

The statistical characteristics of the operation of the QS simulated by this device are calculated by known methods based on the readings of the counters.

Claims (1)

The Invention Formula A device for simulating queuing systems, comprising a block of random pulse generators, a block of incoming orders, a block of unattended requests, a block of reverse queue length counters, a busy channel counter, three elements OR, And, two groups of elements And, the first block of elements And, two elements of the prohibition, the block of random time delays, a group of elements of the prohibition, the outputs of the block of random-pulse generators, the quotation is connected to strokes counters for received block wok, first inputs of AND gates of the first group and the data inputs prohibition elements of the group, the control inputs of which are combined with the second inputs of the same elements AND of the first group and connected respectively to the outputs of the elements AND of the second group, the outputs of the elements of the prohibition of the group are connected respectively to the inputs of the first OR element and to the information inputs of the first block of AND elements whose outputs are connected respectively, with summing inputs, a block of reversible queue length counters, the discharge outputs of which reversible counters are connected respectively with the inputs of the second elements Group 5, output of the first element OR - with information entry of the first element the prohibition, the output of which is connected to the summing input of the reversible counter occupied channels, the bit outputs of which are connected respectively to the inputs of the AND element, the output of which is connected to the control inputs of the first block of AND elements and the first prohibition element, the output of the second OR element is connected to 5, the control input of the second prohibition element, the output of which is connected to the subtractive input of the reversible counter of occupied channels, so that, in order to expand the scope of application by simulating a cyclic acceptance discipline from queues to service, it additionally contains a block of prohibition elements, two blocks of OR elements, a second block of AND elements and 5 block of the analysis of the queue consisting of two groups of elements AND, a group of elements NOT and a group of elements OR, and in the block of analysis of the queue the output of each element OR of the group is connected to the first inputs of the corresponding elements AND of the first and second groups, and the outputs of the elements are NOT groups of respectively with the second inputs of the elements of the second group, the output of the K-th element of the second group (K 1, N-1) is connected to the first input of the (K + 1) -th element of the OR group, and the output of the N-ro element AND of the second group is connected to the first the input of the first element OR group, the outputs of the elements AND the second group of the block of analysis of the queue - respectively, with the subtractive inputs of the block of reversible queue length counters and with the inputs of the first group of the first block of OR elements. the inputs of the second group of which are connected respectively to the outputs of the prohibition block, the control input of which is connected to the output of the AND element, and the information inputs of the block of prohibition elements are connected respectively to the outputs of the prohibition elements of the group, the outputs of the first block of OR elements are connected respectively, with inputs of random time delays, the outputs of which are connected respectively to the information inputs of the second block of elements AND and the inputs of the third element OR, the output of which is connected to the information input of the second element of an eepret; block of elements OR whose outputs connected respectively to the inputs of the NOT elements of the groups and the second inputs of the elements AND of the first group of the analysis block of the queue and the inputs of the second element OR, the output of which is connected to the control input of the second block of elements AND, whose K-output is connected to the second input (K + 1) - the first OR element of the group of the analysis of the queue, and the Nth output of the second block of the AND elements is connected to the second input of the first OR element of the group of the analysis of the queue. FIG g