Adjustment of buffer credits and other parameters in a startup phase of communications between a plurality of channels and a control unit
First Claim
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1. A method, comprising:
- providing, by a control unit, a number of buffer credits, to one or more channels, in response to an initiation of a startup phase of communication between the one or more channels and the control unit, wherein the provided number of buffer credits when used for transferring data causes transfer ready operations but no retry operations, wherein the initiation of the startup phase occurs, in response to the one or more channels logging on to the control unit;
subsequent to providing the number of buffer credits, monitoring, by the control unit, communication for a period of time to determine a number of retry operations and a number of transfer ready operations, wherein a waiting time between each monitoring is adequate to allow input/output (I/O) operations in flight to complete; and
in response to the monitoring, iteratively increasing, by the control unit, the number of buffer credits by an amount that is high enough to cause within a predetermined amount of time from the initiation of the startup phase, an occurrence of at least one of;
an elimination of any transfer ready operations and retry operations.
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Abstract
A control unit provides a number of buffer credits, to one or more channels, in response to an initiation of a startup phase of communication between the one or more channels and the control unit, where the provided number of buffer credits when used for transferring data causes transfer ready operations but no retry operations. The control unit iteratively increases the number of buffer credits by an amount that is high enough to eliminate any transfer ready operations or cause retry operations to occur within a predetermined amount of time from the initiation of the startup phase.
86 Citations
20 Claims
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1. A method, comprising:
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providing, by a control unit, a number of buffer credits, to one or more channels, in response to an initiation of a startup phase of communication between the one or more channels and the control unit, wherein the provided number of buffer credits when used for transferring data causes transfer ready operations but no retry operations, wherein the initiation of the startup phase occurs, in response to the one or more channels logging on to the control unit; subsequent to providing the number of buffer credits, monitoring, by the control unit, communication for a period of time to determine a number of retry operations and a number of transfer ready operations, wherein a waiting time between each monitoring is adequate to allow input/output (I/O) operations in flight to complete; and in response to the monitoring, iteratively increasing, by the control unit, the number of buffer credits by an amount that is high enough to cause within a predetermined amount of time from the initiation of the startup phase, an occurrence of at least one of;
an elimination of any transfer ready operations and retry operations. - View Dependent Claims (2, 3, 4, 5)
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6. A system, comprising:
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a memory; and a processor coupled to the memory, wherein the processor performs operations, the operations comprising; providing, by a control unit, a number of buffer credits, to one or more channels, in response to an initiation of a startup phase of communication between the one or more channels and the control unit, wherein the provided number of buffer credits when used for transferring data causes transfer ready operations but no retry operations, wherein the initiation of the startup phase occurs, in response to the one or more channels logging on to the control unit; subsequent to providing the number of buffer credits, monitoring, by the control unit, communication for a period of time to determine a number of retry operations and a number of transfer ready operations, wherein a waiting time between each monitoring is adequate to allow input/output (I/O) operations in flight to complete; and in response to the monitoring, iteratively increasing, by the control unit, the number of buffer credits by an amount that is high enough to cause within a predetermined amount of time from the initiation of the startup phase, an occurrence of at least one of;
an elimination of any transfer ready operations and retry operations. - View Dependent Claims (7, 8, 9, 10)
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11. A computer program product, the computer program product comprising a computer readable storage medium having computer readable program code embodied therewith, the computer readable program code configured to perform operations on a device, the operations comprising:
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providing, by a control unit, a number of buffer credits, to one or more channels, in response to an initiation of a startup phase of communication between the one or more channels and the control unit, wherein the provided number of buffer credits when used for transferring data causes transfer ready operations but no retry operations, wherein the initiation of the startup phase occurs, in response to the one or more channels logging on to the control unit; subsequent to providing the number of buffer credits, monitoring, by the control unit, communication for a period of time to determine a number of retry operations and a number of transfer ready operations, wherein a waiting time between each monitoring is adequate to allow input/output (I/O) operations in flight to complete; and in response to the monitoring, iteratively increasing, by the control unit, the number of buffer credits by an amount that is high enough to cause within a predetermined amount of time from the initiation of the startup phase, an occurrence of at least one of;
an elimination of any transfer ready operations and retry operations. - View Dependent Claims (12, 13, 14, 15)
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16. A storage controller in communication with one or more hosts, the storage controller comprising:
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a memory; and a processor coupled to the memory, wherein the processor performs operations, the operations comprising; providing, by a control unit of the storage controller, a number of buffer credits, to one or more channels, in response to an initiation of a startup phase of communication between the one or more channels and the control unit, wherein the provided number of buffer credits when used for transferring data causes transfer ready operations but no retry operations, wherein the initiation of the startup phase occurs, in response to the one or more channels logging on to the control unit; subsequent to providing the number of buffer credits, monitoring, by the control unit of the storage controller, communication for a period of time to determine a number of retry operations and a number of transfer ready operations, wherein a waiting time between each monitoring is adequate to allow input/output (I/O) operations in flight to complete; and in response to the monitoring, iteratively increasing, by the control unit of the storage controller, the number of buffer credits by an amount that is high enough to cause within a predetermined amount of time from the initiation of the startup phase, an occurrence of at least one of;
an elimination of any transfer ready operations and retry operations. - View Dependent Claims (17, 18, 19, 20)
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Specification