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 Method and apparatus for processing input/output request by using a plurality of channel buses

Details
Inventors: Koyama, Susumu;
Assignee: Fujitsu Limited (Kawasaki, JP)
Primary Examiner: Meky; Moustafa M.
Assistant Examiner:
Attorney, Agent or Firm: Greer, Burns & Crain Ltd.

With respect to each of low speed and high speed input/output ports of an input/output control unit, an activation time from a time point when an end status in association with the end of transfer is responded to a time point when an activation request is received is measured and stored in a memory. When the high speed port receives an activation request from a high speed channel, the activation time in the memory measured with respect to the low speed port is read out and an input/output request for the low speed port is preferentially accepted for such an activation time. As an activation time of the low speed port, the minimum time, average time, and maximum time are obtained from the result of the measurement. Either one of the above three times is selected as an activation time so as to almost equalize busy ratios of the high speed port and low speed port.

DETAILED DESCRIPTION According to the present invention, there are provided method and apparatus in which even if speeds of a plurality of channel buses for connecting a channel of a host computer and input/output ports of an input/output control unit are different, processes for input/output requests can be equivalently executed without one-siding to a specific input/output port.
First, the invention provides an input/output control unit in which a plurality of channels on the upper apparatus side are connected to a plurality of input/output ports through channel buses of different transfer speeds.
Specifically speaking, the invention provides an input/output control unit having a high speed input/output port and a low speed input/output port connected respectively to a high speed channel unit and a low speed channel unit on the host side through channel buses of different transfer speeds.
According to the first form of the invention, each of, for example, two input/output ports (A, B) in the input/output control unit has an activation time measurement storing section for measuring and storing an activation time from a time point when a response of a busy cancellation in association with the end of the transfer of the other input/output ports to a time point when the next activation request is received.
When the activation request is received from a high speed channel (B) to a high speed input/output port (B) by a route control section, an activation request for the low speed input/output port (B) is waited for the activation time T2 of the low speed input/output port (B) stored in the activation time measurement storing section.
When there is an activation request to the low speed input/output port (B) for such a waiting time, the I/O port (B) is coupled to a corresponding low speed channel (B) and a transferring process is executed.
When there is an input/output request from a high speed channel unit (A) for a period of time during which the low speed input/output port (B) waits for the activation request, a busy response is returned and the input/output request is not accepted



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