JPS63113750A - Information processing system - Google Patents

Abstract

PURPOSE:To ensure transfer of data with high system efficiency by always monitoring the using frequency of a system bus every unit time and switching a data transfer mode using the system bus to a burst mode or a normal mode in accordance with the using frequency of the bus. CONSTITUTION:A bus using frequency measuring part 31 of an equipment 30-1 measures the bus using frequency for each unit time T via a signal line 34 and based on a bus request signal supplied through a bus request signal line of a system bus 20. A control part 32 of the equipment 30-1 informs a start request to a bus interface part 33 when the transfer of data is needed with another equipment via the bus 20. The part 33 decides that the transfer of data is permitted in a burst mode when a bus using frequency display signal is equal to logic '0' and therefore the latest using frequency of the bus 20 is less than a reference level. While the part 33 decides that the transfer of data is not permitted in a burst mode when the bus using frequency display signal is equal to logic '1' and therefore the latest using frequency of the bus 20 is more than the reference level.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Field of Application)] The present invention relates to an information processing system equipped with a system bus that interconnects various devices, and particularly relates to an information processing system that is used for data transfer between various devices. This invention relates to a transfer mode switching method.

(Prior Art) This type of information processing system has a memory 11.0 as shown in FIG. CPU12. Various input/output devices (Ilo) 1
It has 3rd grade equipment. These devices are connected to the system bus 14 and perform data transfer using the system bus 14 while competing for the bus with each other.

Now, in the system shown in FIG. 2, when data is transferred between devices connected to the system bus 14, the bus 1
A device that wishes to use the bus 14 sends a bus request signal onto a predetermined signal line of the bus 14. At this time, if bus request signals are also output from other devices, a bus contention is carried out between these devices requesting to use the bus as shown in FIG. to perform data transfer cycles. When the device that wins the bus contention executes one data transfer cycle, the next bus contention is performed again. Data transfer in which bus contention cycles and data transfer cycles are repeated in this manner is called data transfer in normal mode.

Data transfer in the normal mode described above has the disadvantage that high-speed transfer is difficult because a bus contention cycle is required every time one data transfer cycle is completed.

Therefore, in the system shown in FIG. 2, in order to increase the speed of data transfer, data transfer using the burst mode described below can be applied.

In this burst mode, when a device that wants to continuously transfer data obtains the right to use the system bus 14 through bus contention, it sends a BUSY signal to the system bus 14 as shown in FIG. 3(b). The device that outputs this BIJSY signal can continuously execute data transfer (data transfer cycle) without competing for the bus during the output period.

The data transfer in the burst mode described above is certainly effective in a system in which there are few devices connected to the system bus 14, data transfer between devices is performed only sparsely, and the number of times of bus contention is small. However, in a system where a large number of devices are connected to the system bus 14 and there is a lot of data transfer between devices, if burst mode data transfer is frequently used, other devices that require data transfer will not be able to use the system bus 14. There was an issue where it took a long time to obtain the item. This problem was particularly acute for devices with low priority for bus usage.

(Problems to be Solved by the Invention) As described above, in conventional information processing systems, when data transfer using the system bus is performed in normal mode, high-speed transfer is difficult, and when performed in burst mode, it is difficult to transfer data using the system bus. There was a problem where data transfer took a long time.

This invention has been made in view of the above circumstances, and its purpose is to provide an information processing system that can perform data transfer operations with high system efficiency by switching data transfer modes depending on the usage level of the system bus. It's about doing.

[Structure of the Invention (Means and Effects for Solving Problems) This invention measures the degree of use of a system bus that interconnects various devices per unit time, and sets this degree of use to a predetermined reference value. By providing a bus usage measuring means that outputs a bus usage display signal indicating whether or not the bus usage is higher than or equal to This system dynamically selects one of the transfer modes and performs data transfer in the selected transfer mode.By switching the data transfer mode according to the usage of the system bus, data transfer with high system efficiency is achieved. is possible.

(Embodiment) FIG. 1 shows a block configuration of an information processing system according to an actual example of the present invention. In the figure, 20 is a system bus, and 30-1, 30-2, . In the device 30-1, 31 measures the degree of use of the system bus 20 for each unit time based on the bus request signal on the bus request signal @1jl (not shown) of the system bus 20, and the degree of use is set in advance. 32 is a control unit that controls the entire device 30; 33 is a system controller that outputs a bus usage display signal indicating whether or not the r$ value is greater than or equal to the base r$ value; 32 is a control unit that controls the entire device 30; bus 2
This is a bus interface unit that performs data transfer using 0, bus contention, etc.

During data transfer, the bus interface unit 33
It has a function of selectively switching the data transfer mode according to the bus usage display signal from the bus usage measurement unit 31.

34 is a signal line for transmitting the bus request signal on the bus request signal line of the system bus 20 to the bus usage measuring section 31; 35 is a signal line for transmitting the bus usage display signal outputted from the bus usage measuring section 31 to the bus interface section 33; It is a signal line for transmission. 36 is a signal line for transmitting a start request from the control section 32 to the bus interface section 33 to instruct the start of a data transfer procedure, and 37 is an internal bus of the device 30-1. A control section 32 and a bus interface section 33 are connected to the internal bus 37. 38 is a signal line for transmitting the bus request signal output from the bus interface section 33 onto the bus request signal line of the system bus 20;
39 is a signal line that transmits the BUSY signal output from the bus interface section 33 to the BUSY signal line (not shown) of the system bus 20 during the data transfer period in burst mode; 40 is a data bus (not shown) of the system bus 20; figure)
This is a data line used for data transfer between the bus interface section 33 and the bus interface section 33.

Although the devices 30-2 to 30-n are omitted in FIG. 1, they are the same components as the bus usage measurement unit 31, control unit 32, and bus interface unit 33 provided in the device 30-1. have.

Next, the operation of the configuration shown in FIG. 1 will be explained. The bus usage measuring unit 31 of the i-device 30-1 measures the bus usage for each unit time T based on the bus request signal derived from the bus request signal line of the system bus 20 via the signal line 34. There is.

For this measurement, for example, a counter (not shown) is used which counts up each time the bus request signal becomes active and whose count value is cleared every time T. Only when the count value of this counter exceeds a preset reference value, the bus usage measurement unit 31 outputs a logic “1'' during the next measurement cycle (i.e., unit time T).
A bus usage level display signal of 1 is output onto the signal line 35.

Now, when it becomes necessary to perform data transfer using the system bus 20 with another device, the control section 32 in the device 30-1 connects the signal line 3 to the bus interface section 33.
The start request is notified via 6. Upon receiving the start request from the control unit 32, the bus interface unit 33 determines whether data transfer in burst mode is permitted based on the logic state of the bus usage indicator signal on the signal line 35. That is, the bus interface unit 33 allows data transfer in burst mode if the bus usage level display signal is a logic 4°O'' and the latest usage level of the system bus 20 does not meet the reference value. If the bus usage indication signal is logic ``1'' and the latest usage of the system bus 20 is equal to or higher than the reference value, it is determined that data transfer in burst mode is not permitted. .

Next, the bus interface unit 33 outputs a bus request signal to the bus request signal line of the system bus 20 via the signal line 38 to contest the bus. and bus interface section 3
3, when the right to use the system bus 20 is acquired through this bus contention, if the bus usage display signal from the bus usage measuring unit 31 is logic "OI+" (that is, the usage of the system bus 20 is low). state), system bus 20
The 5usy signal is outputted to the BUSY signal line of the computer via the signal line 39, and data transfer with the desired device is performed via the data line 40 and the system bus 20 in burst mode as shown in FIG. 3(b). Execute. In this burst mode data transfer, once the right to use the system bus 20 is acquired, there is no need to contend for the bus every data transfer cycle, and data transfer cycles can be performed continuously, resulting in high-speed transfer. It becomes possible. Furthermore, data transfer in this burst mode is permitted only when the system bus 20 is used at a low level, so there is almost no effect on other devices.

On the other hand, if the bus usage level display signal from the bus usage measurement unit 31 is logic “1” (that is, when the system bus 20 is in a high usage state), the bus interface unit 33 outputs the BUSY signal. Instead, data transfer is performed in the normal mode as shown in FIG. 3(a). In data transfer in this normal mode, bus contention is performed every time one data transfer cycle is completed.

In the above embodiment, the usage of the system bus is determined by measuring the number of times a bus request signal is output to the system bus per unit time, but the signal to be measured is not limited to the bus request signal. Instead, any signal that can measure the usage of the system bus may be used, such as a data reception signal (response signal) returned by a device that has received data. Further, in the embodiment described above, each device connected to the system bus is provided with a bus usage measurement unit, but the present invention is not limited to this. For example, only one bus usage measuring unit may be provided in the system and shared by each device. However, in this case, it is necessary to add a bus usage display signal line to the system bus 20 for transmitting the bus usage display signal from the bus usage measurement unit to each device (bus interface unit within). . Furthermore, it goes without saying that low-speed devices that do not require data transfer in burst mode do not need to be provided with a mechanism for selectively switching the data transfer mode using the bus usage indicator signal.

[Effects of the Invention] As detailed above, according to the present invention, the degree of use of the system bus per unit time is constantly monitored, and the transfer mode of data transfer using the system bus is changed according to the degree of use at that time. Since the mode is switched to either burst mode or normal mode, data transfer operation can be performed with high system efficiency.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an information processing system according to an embodiment of the present invention, Fig. 2 is a block diagram of a general information processing system, and Fig. 3 explains data transfer in normal mode and burst mode. This is a timing chart. 20... System bus, 30-1 to 30-n... Equipment, 31... Bus usage measuring unit, 32... Control unit,
33...Bus interface section. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) In an information processing system that is equipped with a system bus that interconnects various devices, and in which data transfer between these devices is performed via the system bus, the degree of use of the system bus per unit time is measured, and the usage of the system bus is measured. a bus usage measuring means that outputs a bus usage display signal indicating whether the bus usage level is equal to or higher than a predetermined reference value; and a bus interface means provided in each of the above-mentioned devices, The bus interface device dynamically selects either a normal mode or a burst mode in response to the bus usage indication signal, and performs data transfer in the selected transfer mode. Information processing system. (2) The bus interface means selects the normal mode when the bus usage level display signal indicates that the usage level of the system bus is equal to or higher than the reference value, and the bus interface means selects the normal mode when the bus usage level display signal indicates that the usage level of the system bus is equal to or higher than the reference value. 2. The information processing system according to claim 1, wherein the burst mode is selected when the burst mode is indicated.