US 5,333,271 AGranted

Methods and apparatus for performing data chaining in data streaming mode through a channel extender

AssigneeInternational Business Machines Corporation

InventorsKenneth J. Fredericks, Thomas A. Gregg, Kenneth A. Meifert, Jr., Anthony R. Sager, John F. Santiamo, Clifford T. Williams

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Abstract

Methods and apparatus are described, in the context of an information handling system, that permit data chaining in a data streaming mode to be performed through a channel extender. The information handling system includes a processor channel and a peripheral device controller which communicate with one another over the channel extender. The invention allows the separation between the processor channel and peripheral device controller to be extended up to several (e.g. 1, 2 or 3) kilometers versus the less than 0.5 kilometer separation imposed by state of the art systems. Furthermore, the invention allows the objective of increased channel extender length to be accomplished without the risk of data overruns, chaining checks or peripheral device controller signalled errors which would otherwise occur as a result of requests for data or data transfers being in flight on an extended link.

Claims7

Dependent claims

In an information handling system having a processor channel, a controller for controlling a peripheral device and operated by said processor channel for performing data transfers, including data bytes and data transfer tags, between said processor channel and said controller in a data streaming mode, a circuit for generating a Data Streaming Mode (DSM) signal which is active when a data transfer is in the data streaming mode and inactive when said data transfer in not in the data streaming mode, said channel controller generating a Suppress Out (SO) signal which is active when said controller is to stop a data transfer to said processor channel and inactive when said controller may perform a data transfer to said processor channel, an In Tag Buffer (ITB) apparatus comprising:

a data link between said processor channel and said controller forming a pipeline through which data bytes and data transfer tags flow from said controller to said processor channel during a data transfer;
latch means having an input connected to said pipeline and an output, said latch means for latching data bytes and their associated data transfer tags flowing through said pipeline from said controller;
ITB control means connected to said processor channel for receiving said SO signal and sending a Device Suppress Out (DSO) signal to said controller which is active when said SO signal is active, said active DSO signal for stopping the data transfer from said controller when received by said controller;
storage means having an input connected to the output of said latch means, an output, a first control terminal connected to said channel for receiving said SO signal, and a second control terminal connected to said circuit for receiving said DSM signal, said storage means draining said pipeline and storing data bytes and their associated data transfer tags therein when said SO signal is active, said data bytes and their associated transfer tags being written into and read out of said storage means when said DSM signal is active and said SO signal is inactive;
and
gate means having an input connected to the output of said storage means, an output connected to said processor channel, and a control terminal connected to said circuit for receiving said DSM signal, said gate means for transferring said data bytes and their associated data transfer tags from said storage means to said processor channel when said DSM signal is active.

3 more elements

establishing a data link between said processor channel and said controller, said data link forming a pipeline through which data bytes and data transfer tags flow from said controller to said processor channel during a data transfer;
latching in a latching means connected to said pipeline, data bytes and their associated data transfer tags flowing through said pipeline from said controller;
receiving said SO signal by an In Tag Buffer (ITB) control means connected to said processor channel;
sending an active Device Suppress Out (DSO) signal from said ITB control means to said controller when said SO signal is active;
stopping the data transfer from said controller when said active DSO signal is received by said controller;
providing a storage means having an input connected to the output of said latch means, an output, a first control terminal connected to said channel for receiving said SO signal, and a second control terminal connected to said circuit for receiving said DSM signal;
draining data bytes and their associated data transfer tags from said pipeline into said storage means when said SO signal is active;
both writing into and reading out of said storage means, data bytes and their associated data transfer tags when said DSM signal is active and said SO signal is inactive;
providing gate means having an input connected to the output of said storage means, an output connected to said processor channel, and a control terminal connected to said circuit for receiving said DSM signal;
and
transferring through said gate means, said data bytes and their associated data transfer tags from said storage means to said processor channel when said DSM signal is active.

8 more elements

Dependencies are inferred from the claim text.