Patent ID: 7930438
Filing Date: 2011-04-19
Classification: G06F

Abstract:
1. A method of facilitating input/output (I/O) communication in a processing environment having an I/O link handling complex instruction chains for a processing operation, the method comprising: obtaining by an I/O communications adapter of the processing environment an interrogate command, the interrogate command querying for status information of the processing operation to be provided in an interrogate response; throttling a fixed number of resources and a time allocated to the interrogate command by pre-allocating the fixed number of resources, selecting at least one of the fixed number of resources for the interrogate command, and maintaining a timestamp for a interrogate message incorporating the interrogate command; and forwarding from the I/O communications adapter to a control unit of the processing environment the interrogate message, wherein: if the interrogate response is not received by the I/O communications adapter from the control unit within a limited timeout period as measured by the timestamp and the interrogate command is received while the fixed number of pre-allocated resources are in use, the I/O communications adapter returns a busy response indicating the control unit is busy to prevent overrunning the control unit; if the interrogate response is received by the I/O communications adapter from the control unit within a limited timeout period as measured by the timestamp and the interrogate command is received while the fixed number of pre-allocated resources are not in use, returning the interrogate response; if the interrogate response is not received within the limited timeout period, determining that the interrogate response is stale; and if the interrogate response cannot be sent or queued to the I/O communications adapter in a single dispatch, the interrogate response is discarded.