SU1536397A2 - Device for modelling queueing systems - Google Patents

Abstract

The invention relates to computing and can be used to study queuing systems. The purpose of the invention is to expand the functionality of the device by simulating the adaptation of the flux density of the quotation to the number of the quotation that is denied service. The device contains a generator 1 for the wok, the first counter 2 for the wok, the first counter 3 failures, the counter 4, the number of exceeding service time, the first reversible counter 5, the second element AND 6, the first element AND 7, the element OR 8, the first element 9 of the ban, the second block 10 and the first block 11 of the random time delay, the second counter 12 of the wok, the second counter 13 of failures, trigger 14, the second prohibition element 15, the third element AND 16, the second reversible counter 17. Those coming from the generator 1 are serviced according to a simulated random law distribution. If all service channels are busy, a denial of service occurs. Depending on the ratio of the number of applications sent and the number of applications that are denied service, the code value changes at the bit outputs of the second reversible counter 17 and the density of the generator 1 flow changes with controlled flow density. This makes it possible to determine automatically the value of the flux density at which the specified ratio of sent and lost bids is maintained. 1 il.

Description

The invention relates to computing, can be used to study queuing systems and relates to the improvement of the device according to the author. St. № 1 151980.

The purpose of the invention is to expand the functionality of the device by simulating the adaptation of the flux density of the quotation to the number of the denied service.

The drawing shows a block diagram of the proposed device.

The device contains a generator 1 for the wok, the first counter 2 for the wok, the first counter 3 failures, the counter 4, the number of exceeding service time, the first reversible counter 5, the second element AND 6, the first element AND 7, the element OR 8, the first element 9 of the ban, the second 10 and the first 11 blocks of the random time delay, the second counter 12 of the wok, the second counter 13 of the failures, the trigger 14, the second element 15 of the ban, the third element And 16, the second reversible counter 17.

Verbal model of the device operation is as follows.

The device simulates a mode in which a limitation is imposed on the service time of the demand. Thus, the applications entering the system are lost not only when part of the channels (or all of them) are serviced, and the rest are under repair, but also when the service time of the application exceeds the allowable one. The applications received from the generator are serviced by the device according to a simulated random distribution law. If all service channels are busy, then a denial of service occurs. Depending on the ratio of the number of applications sent and the number of denials of service, the generator flux density of the application with controlled flux density periodically changes. The direction of this change is automatically chosen so that the device establishes the specified ratio of sent and lost quotations. This allows you to automatically determine the value of the flux density at which the specified ratio of sent and lost values is maintained.

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as a result of a denial of service charge.

The device works as follows.

The pulses from the generator 1 are received at the input of counter 2, the volume of which is calculated for the entire simulation experiment, and the input of counter 12, the volume of which determines the frequency of checking the ratio of sent and lost as a result of the refusal. In addition, pulses from generator 1 are received through an open prohibition element 9 to the summing input of the reversible counter 5 and to the summing inputs of blocks 10 and 11 of a random time delay simulating the service process and the process of setting the maximum allowable service time, respectively.

The arrival of a pulse at the summing input of counter 5 increases its code by one, which means that one channel is occupied. At the same time, if the service time of the application does not exceed the allowable service time specified by block 11, then the pulse that appeared at the output of block 10, after a time equal to a random service duration, goes to the subtractors of the input of counter 5 and writes off the unit from it, thereby imitating the release of one channel. The same pulse from the output of block 10 is fed to the input of block 11 of a random time delay, prohibiting the appearance of a pulse at the output of this block.

If the service time of the application exceeds the maximum allowable, then the pulse at the output of the block 11 of the random time delay after a time equal to the random value of the maximum allowable time of the service goes to the subtracting input of the block 10 of the random time delay and to the subtracting input of the counter 5, thereby imitating termination of the service provided by the application and the release of one channel. In addition, the pulses from the output of block 11 of a random time delay arrive at the input of counter 4, counting the number of applications whose service time exceeds the maximum allowable.

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In the process of servicing the device, a situation may arise when all channels are busy. In this case, at the output of the element 6, a signal arrives at the control input of the prohibition element 9 and at the input of the element 7. The prohibition element 9 is blocked and the pulses from the generator 1 through the open element And 7 arrive at the input of the failure counter 3 and the counting counter input 13 failures, imitating the flow of quotations that were denied service because of the lack of free channels.

As the pulses from the outputs of blocks 10 and 11 are sent to the subtracting input of the reversible counter 5, the prohibition element 9 is re-opened, thereby allowing the arrival of pulses from the generator 1 to the summing inputs of blocks 10 and II.

The counter 3 failure rate is calculated for the entire period of the simulation experiment, and the failure counter 13 volume is determined by the maximum permissible number of failures in the period between checks of the ratio of sent and lost due to a refusal.

At the output of the overflow of the counter 12, a wok impulse appears after counting a certain number of sent applications. Thus, the counter 12 sets the period for accessing the data accumulated by the failure counter 13. The size of the counter 13 failures is equal to the maximum permissible number of failures in the interval between the checks on the ratio of the sent and lost as a result of the failures per wok. Therefore, if during the reference period specified by the volume of the counter 12 of the wake, the number of failures did not exceed the maximum allowable value, then the counter 13 of the failures does not overflow and the trigger 14 remains in the initial zero state, its output will be a logic zero signal. In this case, the element And 16 will be locked, and the element 15 of the ban is open. At the end of the next circulating period, the counter 12 behind the wok overflows and, from its overflow output, the pulse can flow to the summing input of the reversing counter 17.

If, during the period of circulation, the number of service failures exceeds

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the maximum permissible value, then the counter 13 of failures has time to overflow and the pulse from the overflow output of this counter, arriving at the input of the trigger 14, translates it into a single state. At the same time, at the output of trigger 14, a logical unit appears, which opens element YI 16 and element 15 of the prohibition. Therefore, the pulse from the overflow output of the counter 12 of the wok through the element 16 can enter the subtraction input of the reversible counter 17. 15 Thus, each overflow pulse from the output of the counter 15 behind the wok enters the input of the summation or subtraction of the reversible counter 17, bit the outputs of which 2Q are connected to the control inputs of generator 1 for wok.

Preparing for the next evaluation cycle, the ratio of sent and lost orders is carried out with a 25 pulse from the overflow output of the counter 12 for the wok to the reset input of the counter 13 failures and trigger input 14, due to which the counter 13 is zeroed and the trigger 14 goes to IS - 30 is the best-selling zero state. A change in the code combination at the output of the reversible counter 17 leads to a change in the flux density of the generator 1 per wok. Thus, the flow of the generator 1 of the wok is automatically adjusted to a value at which the specified ratio between the number of sent applications and the requisition that is denied in the service 40 is maintained.

Claims (1)

Invention Formula A device for simulating a system of queuing under aut. St. No. 1151980, different. That is, in order to expand the functionality by simulating the adaptation of the density 0 of the flow of the flow rate to the number of the service that is denied service, it additionally contains a second counter of the flowmeter, the second failure counter, a trigger, the second prohibition element, the third the element And and the second reversible counter, and the bit outputs of the second reversing counter are connected respectively to the inputs of the pulse frequency control in the gene 7 15363978 Rator quotation, the output of which is a submente AND connected to the counting input It is connected to the information input of the second-second counter of failures, output  a wok counter whose overflow-overflow output is connected to which is connected to the trigger input of the trigger directly Resetting the second counter of failures, the output of which is connected to the control input of the third element AND, the second input of the prohibition element trigger trigger input and information and second input of the third element 1) (the ion inputs of the second element, the output of which is connected to the subtraction of the output, the output of which is connected to the input of the second reversible summing the input of the second rever-counter, a live counter, the output of the first