JPS62144265A - Data transfer system - Google Patents

Abstract

PURPOSE:To improve the DMA transfer efficiency to the discontinuous areas by adding the address value showing the access intervals of a main memory and the number of bytes stored continuously in each DMA transfer to a channel command word. CONSTITUTION:A channel command word (CCW)21 is first prepared on a main memory device (MS) before the DMA transfer is executed. The CCW21 includes a data address designating part (DA)211 which designates the head address for memory access in a DMA transfer mode, a byte counter (BC)212 which instructs the total number of transfer bytes, the number (B)213 of bytes which are continuously stored in the MS, and the address value (A)214 which shows the access intervals of the MS in a DMA transfer mode. When an input/output instruction is delivered, the DMA transfer of bytes B is carried out plural times from the position on the MS shown by the DA211 at the intervals designated by the DA211.

Description

[Detailed Description of the Invention] [Summary] Direct memory access in an information processing system (
In the data transfer method using the DMA) method, the channel command word (CCI) prepared on the main memory (MS) is
II) is the start memory address (D) required for DMA transfer.
A), the total number of transferred bytes (BC), and the address value (8) indicating the access interval when transferring the leaf A, once.

Alternatively, by setting the number of bytes (8) that are consecutively stored in multiple DMA transfers, it is possible to send data to DM8 to discontinuous areas at regular intervals with one input/output command. This is how it was done.

[Industrial application field]

The present invention relates to a data transfer method using direct memory access (DMA) in an information processing system.

In data transfer using conventional direct memory access (DMA), it has been common to access continuous areas on memory.

However, with the recent improvements in the functionality of computer systems, data processing using these computer systems has come to be performed in various fields.For example, data processing in production control systems, so-called plant systems, , it is necessary to collect measurement data (time, temperature, production volume, etc.) on the production line.

In this case, a unit that is easy to process by the software in the computer system (for example, temperature at any given time).

It is better to divide the data into parts (production volume, etc.) and store them at regular intervals.

Due to these circumstances, direct memory access (DM)
In the data transfer method according to A), data that is generated non-sequentially is pooled in a data buffer such as an adapter with a certain regularity, and the pooled non-sequential data is transferred into one data buffer. There is a need for a data transfer method that can efficiently transfer input/output instructions to non-contiguous areas of the main memory (MS).

[Prior art and problems to be solved by the invention] FIG. 4 is a diagram schematically showing a conventional DMA transfer system.

In conventional DMA transfer, as is clear from this figure, when issuing one input/output command, the main memory (
MS) Channel command words prepared on 2 (hereinafter referred to as
and a data address designation unit (DA) 211 that designates the first memory address on the main storage device (old) for transfer to the relevant data designated by the CCW) 21.

Byte count specification section (BC) 2 indicating the total number of transferred bytes
12, the data addressing section (DA) 21
From the position indicated by 1, byte count specification section (BC)
Data transfer was being performed to a continuous area designated by 212 (indicated by diagonal lines).

Therefore, in order to store data in a non-contiguous area with a specific number of bytes at regular address intervals, it is necessary to: After the transfer, for example, use an inter-memory transfer command, etc. to store it again in the non-contiguous area, or
Alternatively, it is necessary to directly store the data in a linearly discontinuous area using a known chain data method.

In the method (2), there is a problem that the program processing becomes complicated and the burden on the software becomes heavy.

In the method (2), before executing each DMA transfer, it is necessary to fetch each chained CC-, which causes problems such as poor access efficiency and, in the worst case, data overrun. there were.

In view of the above-mentioned conventional drawbacks, the present invention stores discontinuously generated data in a discontinuous area on the main memory (MS) using DM.
The purpose of this invention is to provide a method for efficiently transferring data using A transfer.

[Means for solving problems]

FIG. 1 is a diagram showing the concept of DMA transfer according to the present invention, in which (a) shows a non-continuous MA transfer area (indicated by diagonal lines) on the main memory (MS) 2, and (b) shows This figure shows the format of the CCW required to implement the present invention.

That is, in the present invention, as shown in this figure (b),
The CCW 21 for executing one input/output instruction includes a data address specification section (D^) 211' that specifies the start address of memory access when sending to the DM8 concerned, and a byte counter that specifies the total number of transferred bytes. In addition to (BC) 212, the number of bytes (B) 213 that are continuously stored in the main memory (MS) 2 and the access interval in the main memory (MS) 2 when transferring to the main memory (MS) 2. An address value indicating (
A) 214 is provided so that ΣB=BC, the CCW 21 of the present invention is prepared before the transfer is executed to the DM, and the input/output command is issued. As such, the start memory address (DA) of the CCW 21
From the position indicated by 211, the number of bytes (B) to be continuously stored in the main memory (MS) 2 is transferred by DMA at an interval of address value (A) 214 indicating the access interval.
The configuration is such that DMA transfer is performed multiple times (specifically, until ΣB=BC).

[Effect]

That is, according to the present invention, in a data transfer method using a direct memory access (DMA) method in an information processing system, the beginning of a DMA transfer is included in a channel command word (CCW) prepared on a main memory (MS). Memory address (D8) and total number of transfers/N/items (BC
) and an address value (
By setting A) and the number of bytes (B) to be stored consecutively in one or more DMA transfers, one input/output command can transfer D to non-contiguous areas at regular intervals.
Since it is designed to be able to perform MA transfer, DMA transfer to a non-contiguous area is performed by starting - times of DMA transfer, and processing time is shortened, resulting in high efficiency for the non-contiguous area. This has the effect of allowing DMA transfer to be performed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a diagram showing an example of the configuration of a data processing system in which the present invention is implemented, and FIG. 3 is a diagram showing an embodiment of the present invention, showing a specific example of a DMA control circuit. be.

The same reference numerals indicate the same objects throughout the figures.

Hereinafter, the DMA transfer method of the present invention will be explained with reference to FIGS. 2 and 3 while referring to FIG. 1.

First, before executing DMA transfer, the main memory (MS)
2, the CCW 21 described in FIG. 1(b) above is shown.
will be prepared.

Here, when a specific program is executed in the central processing unit (CPII) 1 and an input/output command is issued to the adapter 3, the above-mentioned CCW 21 and executes the DMA transfer instructed by the CCW 21.

At this time, in the DMA control unit 31 of the adapter 3, the third
Memory address control as shown in the figure is executed. That is, fl) Data address (DA) update operation: DMA
When the transfer is started, the adapter 3 transfers the main memory t(M
S) After reading ccw 2i from 2 and storing it in an internal control register (not shown), the contents of the data address designation section (DA) 211 are set in the data address register (DA) 311, and data transfer is performed - times. The number of bytes (TB) to be transferred (for example, determined by the bus width of the data transfer bus) is sequentially added by the adder 31a each time data transfer is performed, and when ΣTB=8, the addition is completed. ΣTB
Repeat until = BC.

(2) Update of the number of continuous transfer bytes (B): In synchronization with the operation in (1) above, the number of continuous transfer bytes (B) 213 is updated from the control register where the contents of CCW 21 are stored in the continuous transfer byte register ( B) After being set to 312, the number of bytes (TB) is subtracted by the adder 31c every time the data transfer in units of TB bytes is performed, and when B=O, the adder 31b is subtracted by the adder 31c. At the same time as starting the addition process in the continuous transfer byte register (B) 312
, enter the number of consecutive transfer bytes (B) again from the control register above.
) 213 is set, and the same subtraction process is performed as ΣTB=B
This is repeated until C is reached.

(3) Updating the byte count number (BC): In synchronization with the operation in (1) above, the contents of the byte count specification field (BC) 212 are updated from the control register to the byte counter (BC).
After the number of bytes (TB) is set to 313, each time the aforementioned data transfer in TB byte units is performed, the number of bytes (TB) is set in the adder 31.
d is subtracted, and when BC=O, the data transfer is terminated.

In this way, the present invention provides CCW used during DMA transfer.
21, an address value (A) indicating the access interval on the main memory (MS) during the DMA transfer, and each D? 'lA
Add the number of bytes (B) stored consecutively in the transfer,
The feature is that DMA transfer to the non-transfer 'tf and SJT areas can be executed efficiently.

〔Effect of the invention〕

As described above in detail, the data transfer method of the present invention is based on the channel command GU (ccw) prepared on the main storage device (MS) in the data transfer method using the DMA method in an information processing system. The starting memory address (DA) and the number of bytes to be transferred (B
C), the address value (A) indicating the access interval at the time of the DMA transfer, and the number of bytes (B) that are continuously stored in one or more A transfers.
Since it is possible to perform DMA transfers to non-contiguous areas at regular intervals with one input/output command, DMA transfers to non-contiguous areas can be performed in -times.
This is accomplished by starting the transfer, reducing processing time.
This has the effect of allowing efficient DMA transfer to the non-contiguous area.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the concept of the DMA transfer method of the present invention. FIG. 2 is a diagram showing an example of the configuration of a data processing system in which the present invention is implemented. FIG. 3 is a diagram showing an embodiment of the present invention. FIG. 4 is a diagram schematically showing a conventional DMA transfer method. It is. In the drawing, ■ is the central processing unit (CPU), and 2 is the main memory (MS).
. 21 is a channel command word (CCW). 211 is a data address designation unit (DA). 212 is a byte count designation field (BC). 213 is the number of bytes continuously stored in each DMA transfer (
B). 214 is an address value (A) indicating the access interval on the main memory (MS) during DMA transfer. 3 is an adapter, and 31 is a DMA control circuit. 31a, 31b, 31c, and 31d are adders. 311 is a data address register (DA). 312 is a continuous transfer byte register (B), and 313 is a byte counter (BC). fart

Claims (1)

[Claims] Direct memory access in an information processing system (
This is a data transfer method based on the DMA) method, which uses channel command words (
CCW) (21), the start memory address (DA) (211) of the direct memory access (DMA) and the total number of transferred bytes (BC).
(212), the number of bytes (B) (213) that are continuously stored on the main memory (MS) (2), and the main memory (MS) (213) at the time of the direct memory access (DMA) transfer. 2) Set the address value (A) (214) indicating the access interval on the main memory (MS) with one input/output command.
2) A data transfer method characterized in that data transfer is performed by direct memory access (DMA) to fixed areas provided at fixed intervals above.