摘要:
Disclosed are a method of and system for providing time synchronization among first and second computer systems, where each of the computer systems includes hardware, operating system software and a layer of microcode operating between said hardware and said software. The method comprises the steps of using the microcode of the first computer system to provide a first timestamp, using the microcode of the second computer system to provide a second timestamp and a third timestamp, and using the microcode of the first computer system to provide a fourth timestamp. The method comprises the further steps of using the first, second, third and fourth timestamps to determine a timing difference between the first and second computer systems, and adjusting the timing among said first and second computer systems on the basis of said determined timing difference. Preferably, the first and second computer systems are connected together by a point-to-point link; and the first timestamp is sent from the first computer system to the second computer system, and the second and third timestamps are sent from the second computer system to the first computer system over that point-to-point link.
摘要:
A method for detecting virtual images in a network, the network including a host system and a plurality of physical devices in operable communication with one another, includes forming a query packet at the host system; providing the query packet to at least one of the plurality of physical devices; forming at the at least of the plurality of physical devices a first vector in response to the query packet, the first vector including a bit for each possible virtual image that may be formed in the at least one of the plurality of devices and indicating which of the virtual images are configured and addressable; and providing the first vector to the host system.
摘要:
A computer program product is provided for performing an input/output (I/O) processing operation at a host computer system. The computer program product is configured to perform: obtaining a transport command word (TCW) at a channel subsystem for an I/O operation, the TCW including an address of a transport command control block (TCCB) having a transport command area (TCA) configured to hold a first plurality of device command words (DCW) and control data associated with respective DCWs, the first plurality of DCWs including a transfer TCA extension (TTE) DCW that specifies a TCA extension, the TCA extension configured to hold one or more DCWs and control data associated with respective DCWs; gathering the TCCB from one or more locations specified in the TCCB address and transferring the TCCB to the control unit; gathering the TCA extension specified by the TTE DCW; and transferring the TCA extension to the control unit.
摘要:
A computer program product is configured for performing a method including: generating at least one command message by a channel subsystem of the host computer system, the at least one command message including one or more device command words (DCWs), wherein at least one DCW of the one or more DCWs includes a suppress-length indication (SLI) configured to instruct a control unit to continue to perform the I/O operation in response to the control unit detecting that the data count does not match an amount of data required; receiving an incorrect length (IL) value, the IL value being a first IL value in response to the SLI being a first SLI value and the data count not matching the amount of data required; and responsive to receiving the IL value from the control unit, storing an IL indicator in a subchannel-status word.
摘要:
A computer program product is configured for performing a method including: generating at least one command message by a channel subsystem of the host computer system, the at least one command message including one or more device command words (DCWs), wherein at least one DCW of the one or more DCWs includes a suppress-length indication (SLI) configured to instruct a control unit to continue to perform the I/O operation in response to the control unit detecting that the data count does not match an amount of data required; receiving an incorrect length (IL) value, the IL value being a first IL value in response to the SLI being a first SLI value and the data count not matching the amount of data required; and responsive to receiving the IL value from the control unit, storing an IL indicator in a subchannel-status word.
摘要:
A method of processing communications includes: receiving transmission data over a selected time interval for each of a plurality of communication paths between a host processor and a control unit configured to control at least one I/O device; calculating an average round-trip transmission time for each of the communication paths over the time interval; comparing an average round-trip transmission time for a communication path having the highest average round-trip transmission time to a threshold value and to a multiple of an average round-trip transmission time for a communication path having the lowest average round-trip transmission time; and determining, based on comparing the highest round-trip transmission time to the threshold value and to a multiple of the lowest round-trip transmission time, whether the time period indicates a delay in communication between the I/O subsystem and the control unit requiring at least one of a monitoring action and a recovery action.
摘要:
A computer program product, an apparatus, and a method for processing communications between a control unit and a channel subsystem in an input/output processing system are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method including: sending a message from the channel subsystem to the control unit in a first mode; receiving a response from the control unit and determining from the response whether the control unit supports a message protocol; and responsive to the message protocol being supported by the control unit, sending another message using the message protocol from the channel subsystem to the control unit to determine whether the control unit supports a second mode.
摘要:
A computer program product is provided for performing a method including: receiving transmission data over a selected time interval for each of a plurality of communication paths; calculating an average round-trip transmission time for each of the plurality of communication paths over the time interval; comparing an average round-trip transmission time for a communication path having the highest average round-trip transmission time to a threshold value and to a multiple of an average round-trip transmission time for a communication path having the lowest average round-trip transmission time; and determining, based on a result of comparing the highest round-trip transmission time to the threshold value and to a multiple of the lowest round-trip transmission time, whether the time period indicates a delay in communication between the I/O subsystem and the control unit requiring at least one of a monitoring action and a recovery action.
摘要:
An Extended Input/output (I/O) measurement word facility is provided. Provision is made for emulation of the Extended I/O measurement word facility. The facility provides for storing measurement data associated with a single I/O operation in an extended measurement word associated with an I/O response block. In a further aspect, the stored data may have a resolution of approximately one-half microsecond.
摘要:
A computer program product, an apparatus, and a method for processing communications between a control unit and a channel subsystem in an input/output processing system are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes: sending a Process Log-out (PRLO) message from the control unit to the channel subsystem, the message requesting suspension of input/output operations between the control unit and the channel subsystem for a period of time, the period of time being defined by the PRLO message; responsive to the PRLO message, suspending by the channel all input/output operation messages for the period of time, wherein suspending comprises stopping input/output operation messages during the period of time; and responsive to an expiration of the period of time, sending a Process Log-in (PRLI) message from the channel subsystem to the control unit to re-initiate an operating environment between the channel subsystem and the control unit.