Method for balancing the utilization of input/output devices

Claim 3

The method of claim 1 wherein step (a) comprises the step of: counting the number of I/O events that occur in a predetermined time interval, relative to the respective I/O devices in said system being utilized by said currently executing tasks.

Claim 4

The method of claim 2 wherein: said time interval ends with the time at which said task allocating procedure occurs for the task currently undergoing allocation.

Claim 5

The method of claim 3 wherein: said time interval begins when the most recently allocated task underwent allocation, whereby said time interval is that which elapses between successive allocations of different tasks.

Claim 6

The method of claim 2 wherein said operating system includes an input/output supervisor for controlling the accessing of data sets on I/O devices, and wherein said I/O events being counted are the number of times said input/output supervisor is invoked for accessing said data sets.

Claim 7

The method of claim 1 comprising the steps of: d. constructing in said system a task activity table that includes an entry for each I/O device to which each data set associated with a task is allocated, each said entry including a count field; e. incrementing said count field during the course of executing the task associated therewith, each time a data set allocated to said associated device, is accessed.

Claim 8

The method of claim 6 wherein: step (d) is performed during each task allocation so as to create a chain of said tables, and step (d) includes adding said table constructed thereby to said chain.

Claim 9

In a data processing system having a plurality of auxiliary storage I/O devices for storing data sets used in the concurrent execution of a plurality of problem program tasks, said data sets being allocated to said devices during allocation of each task and being accessed by opening thereof during execution of the associated problem program task, the method of balancing I/O activity comprising the steps of: a. counting the number of I/O events on each deviCe connected with open data sets thereon; b. defining during the allocation of data sets of each task the distribution on said devices of data sets which will start to load said devices but which as of allocation have not yet started to load said devices; c. calculating the anticipated loads on said devices based on said events associated with said open data sets and on said data set distribution; d. and allocating data sets to said devices based on the lowest anticipated loads as calculated by said last step.

Claim 10

In a data processing system having a plurality of auxiliary storage I/O devices for storing data sets used in the concurrent execution of a plurality of problem program tasks, said data sets being allocated to said devices during allocation of each task and being accessed by opening thereof during execution of the associated problem program task, the method of balancing I/O activity comprising the steps of: a. counting the number of I/O events on each deviCe connected with open data sets thereon; b. defining during the allocation of data sets of each task the distribution on said devices of data sets which will start to load said devices but which as of allocation have not yet started to load said devices; c. calculating the anticipated loads on said devices based on said events associated with said open data sets and on said data set distribution; d. and allocating data sets to said devices based on the lowest anticipated loads as calculated by said last step.

Claim 11

The method of claim 8 wherein said system includes an operating system having an input/output supervisor invokable by problem program tasks to access data sets, and said I/O events being counted are the number of times said input/output supervisor is so invoked.

Claim 12

The method of claim 8 comprising the steps of: e. creating after all data sets of each task have been allocated, a task activity table including an entry for each device to which the associated data sets are allocated, each entry including a count field for accumulating the count of I/O events due to said associated task on said associated device; f. chaining said table to similar tables previously created; g. and incrementing said associated count field upon the occurrence of the I/O event due to the associated task.

Claim 13

The method of claim 10 comprising the steps of: h. maintaining within said system a device table including one entry for each device in the system, each entry including a field for accumulating data based on said I/O events associated therewith; step (e) including creating in each entry an indication of whether the associated data set is open or closed; i. setting, in response to opening a data set by a problem program task, said indication to open; and step (c) involves sequencing through said chain of activity tables and for open data sets indicated therein, accumulating in the appropriate field of said device table, data derived from said counting of I/O events associated therewith.

Claim 14

The method of claim 8 wherein step (b) includes: the distribution of data sets which were allocated by a prior task allocation but which are unopen at the time of the current allocation, and further includes data sets that have already been allocated by the current allocation.

Claim 15

The method of claim 8 wherein step (a) involves counting said I/O events which occur during a predefined time interval which interval ends at the time of current allocation.

Claim 16

The method of claim 13 wherein step (a) further involves counting said I/O events for data sets which have been open for a period less than said time interval but greater than a minimum predetermined period.

Claim 17

The method of claim 14 wherein: data sets which are open for less than said minimum period are treated as in step (c) on the basis of their distribution rather than on the basis of any count of I/O events.

Claim 18

The method of claim 8 wherein: said counting in step (a) occurs during a predetermined time interval; and step (c) includes calculating an I/O event rate for each device by dividing the number of I/O events by the length of said time interval.

Claim 19

The method of claim 16 wherein step (c) comprises: adding two factors one of which is a device component representing usage of such device and the other of which is a channel component representing usage of the channel to which the device is connected.

Claim 20

The method of claim 17 wherein each of said components includes a first factor indicative of current load and derived from said I/O event rate, and a second factor indicative of pending load and based on said distribution of data sets.

Claim 21

The method of claim 18 wherein: said first factor is obtained by multiplying said I/O event rate for each device by a device-dependent conversion factor representing average access time.

Claim 22

The method of claim 17 wherein: said device component comprises, in The case of an I/O disk drive having a moveable head, a sub-component accounting for standalone seeks during positioning of said head

Claim 23

The method of claim 20 wherein: said sub-component is dependent on an estimate of whether the anticipated seeks will be dominantly interdata-set seeks or intra-data-set seeks.

Claim 24

In a data processing system having an operating system operative to initiate individual job steps and to allocate data sets requested by control statements defining said job steps, said operating system being further operative to control the concurrent execution of multiple tasks during execution of said job steps, the method carried out in said system of balancing operation of the data processing system''s I/O subsystem to optimize the utilization of I/O devices and channels comprising the steps of: a. identifying during the process of allocating a data set to an I/O device, those I/O devices to which such data sets can be allocated; b. determining during allocation of a job step current utilization distribution in said I/O subsystem due to currently executing tasks by counting relative to each I/O device the number of times it has been used over a predefined period of time immediately preceeding such allocation; c. determining during allocation of a job step the anticipated utilization distribution in said I/O subsystem which is expected to result from execution of such job step; d. combining the results of steps (b) and (c) to define the total utilization distribution; e. specifying which of said I/O devices identified in step (a) has the least individual total utilization; f. and allocating a data set of the job step being initiated, to the device specified by step (e).

Claim 25

In a data processing system having an operating system operative to initiate individual job steps and to allocate data sets requested by control statements defining said job steps, said operating system being further operative to control the concurrent execution of multiple tasks during execution of said job steps, the method carried out in said system of balancing operation of the data processing system''s I/O subsystem to optimize the utilization of I/O devices and channels comprising the steps of: a. identifying during the process of allocating a data set to an I/O device, those I/O devices to which such data sets can be allocated; b. determining during allocation of a job step current utilization distribution in said I/O subsystem due to currently executing tasks by counting relative to each I/O device the number of times it has been used over a predefined period of time immediately preceeding such allocation; c. determining during allocation of a job step the anticipated utilization distribution in said I/O subsystem which is expected to result from execution of such job step; d. combining the results of steps (b) and (c) to define the total utilization distribution; e. specifying which of said I/O devices identified in step (a) has the least individual total utilization; f. and allocating a data set of the job step being initiated, to the device specified by step (e).

Claim 26

The method of claim 22 comprising the further step of: adjusting the anticipated utilization distribution each time a data set is allocated to a device to account for the utilization expected to result therefrom.