JPH026094B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a page control method in a virtual storage system, and more particularly to an allocation control method for allocating pages paged out from a real storage device to an external storage device.

[Technology background]

Currently, many data processing devices employ virtual storage systems. In a virtual storage system, the virtual storage space is page-managed, and a certain number of pages or less are set as internal pages on the real storage device, and the remaining pages are set as external pages on an external direct access storage device such as a magnetic disk device (hereinafter referred to as external storage device). In such a system, in order to shorten access time, pages to be processed or pages that are likely to be used need to be placed on the real storage device.

Normally, as shown in FIG. 1, when there is no more available space on the real storage device 1, pages with low usability that can be transferred to an external storage device (referred to as page-out) are transferred to the page replacement mechanism 2. When it is necessary to transfer a new page 4 from the external storage device 3 to the real storage device 1 (referred to as page-in), the previously selected page 5 is transferred to the external storage device 3. A method is used to page out to. and paged out 1
An appropriate slot group of the external storage device 3 is assigned to one or more pages by the external storage management mechanism 6, and the pages are stored therein. Note that a slot is an area on an external storage device in which pages can be stored consecutively, and has the same size as a page. Usually, multiple slots are stored in one track. In addition, the slot group
Each cylinder is comprised of a plurality of slots, typically corresponding to the size of one to several tracks.

As mentioned above, the external storage management mechanism manages slot groups for each cylinder.

FIG. 2 shows a control flow of a conventional slot group allocation control method for external pages, and FIG. 3 shows an external storage management table.

First, depending on the number of pages for which a page-out request is made, a slot group having the number of empty slots that satisfies the number of requests is selected from the external storage management table.

In FIG. 3, the shaded portions indicate allocated slots, and the remaining portions indicate slots that can be allocated. Among the slot groups containing these allocatable slots, one slot group having the least empty slots is selected among the slot groups that satisfy the requested number. If the selection is successful, the allocation ends. On the other hand, if no selection is possible, a slot group containing the most allocatable slots is selected. Once this slot group meets the requested number, the allocation will be terminated.
If the requested number is not met, the next slot group that has the largest number of allocatable slots is selected, and it is determined whether or not these two slot groups together satisfy the requested number. end the assignment when However, if the required number is still not satisfied, the next slot group is selected and it is determined whether or not the required number is satisfied when combined with the previous two slot groups. Thereafter, similar processing is repeated until the allocation is completed.

The conventional slot group assignment method for such paged-out pages, that is, external pages, does not take into account the current cylinder position (head position) of the external storage device. main page device)
In this case, there is a possibility of allocating a slot group that involves a large head movement, which has the drawback of worsening paging input/output response.

[Object and structure of the invention]

The purpose of the present invention is to improve the response of paging input/exit, and for this purpose, the amount of head movement is reduced by allocating the next slot group as close as possible to the head position at the time of the previous access in the external storage device. This provides a means to reduce the

Accordingly, the configuration of the present invention provides the above-mentioned virtual storage system having a real storage device, an external storage device, and a paging control means for managing page-in and page-out between the real storage device and the external storage device. The paging control means is characterized in that when allocating a slot group of the external storage device to an external page paged out from the real storage device, the paging control means selects a slot group that is closest to the slot group accessed immediately before. It is.

[Embodiments of the invention]

The details of the present invention will be explained below with reference to Examples.

FIG. 4 is a configuration diagram of a system according to an embodiment of the present invention. In the figure, 7 is an external storage management mechanism, 8 is a page file dedicated DASD (DASD stands for direct access storage device, the same applies hereinafter), 9 is an auxiliary DASD,
10 is an allocation request page number storage unit, 11 is a DASD management table dedicated to page files, and 12 is an auxiliary unit.
13 is an external page allocation processing section; 14 is a page file dedicated DASD head position storage section; and 15 is a selected slot group storage section.

Auxiliary DASD9 is DASD8 dedicated to page files.
This is a DASD that is used as a backup when the external page can no longer be accommodated.

The number of pages to be paged out is set in the allocation requested page number storage unit 10.

The page file dedicated DASD management table 11 and the auxiliary DASD management table 12 are
This is a management table for external pages on DASD, and is the same as the external storage management table shown in FIG.

The external page allocation processing unit 13 determines slot groups to be allocated to the requested number of external pages, taking into consideration the slot group information in each management table and the head position on the DASD.

Page file dedicated DASD head position storage section 1
4 is set to the cylinder number of the slot group assigned immediately before on the page file dedicated DASD, that is, the head position. Therefore, it will be updated or deleted (as allocated from the auxiliary DASD) when the next allocation is made.

The selected slot group storage section 15 stores the positions (numbers) of one or more slot groups selected in the allocation process.

FIG. 5 shows the control flow of the external page allocation processing section 13. The operation of this embodiment will be explained below according to this flow.

First, the contents of the page file-dedicated DASD head position storage section 14 are checked, and if the previous access was to the page file-dedicated DASD, the page file-dedicated DASD management table 11 is used to determine the access position (head position). Assign the closest slot group that has more free groups than the number of page-out requests. If there is no slot group with free slots equal to or greater than the number of page-out requests, the closest slot group to the previous access position with free slots must be allocated and it must satisfy the number of page-out requests. For example, slot groups with vacant slots are allocated one after another in order of closestness.
The positions of the assigned slot groups are sequentially written into the selected slot group storage section 15.

On the other hand, if the previous access was not to a page file exclusive file, the auxiliary
Using the DASD management table 12, a slot group with free slots equal to or greater than the number of page-out requests is detected, and if there are multiple slot groups, the slot group with the least number of free slots is assigned, and the slot group with the number of free slots equal to or greater than the number of page-out requests is allocated. If there is no slot group with the number of free slots, the slot group with the largest number of free slots is assigned, and the slot groups closest to the selected slot group are assigned one after another until the number of page-out requests is satisfied. When the allocation process ends.

In this way, on the page file dedicated DASD, allocation is always made so that the amount of head movement is minimized, and on the auxiliary DASD, allocation is similarly made so that the amount of head movement is minimized, except for the first selection. will be carried out.

〔Effect of the invention〕

As described above, according to the present invention, the arrangement of external pages in the external storage device is determined in such a way as to minimize the access time associated with head movement, so that the response of paging input/output can be improved. This is especially effective in systems where a DASD dedicated to page files is used.

[Brief explanation of drawings]

Fig. 1 is a general explanatory diagram of paging control in a virtual storage system, Fig. 2 is a control flow diagram of a conventional external page allocation control method, Fig. 3 is an explanatory diagram of an external storage management table, and Fig. 4 is an explanatory diagram of a conventional external page allocation control method. invention 1
The configuration diagram of the embodiment and FIG. 5 are its control flow diagrams. In the figure, 7 is an external storage management mechanism, 8 is a DASD dedicated to page files, 9 is an auxiliary DASD, 10 is an allocation request page number storage unit, and 11 is dedicated to page files.
DASD management table 12 represents an auxiliary DASD management table.

Claims (1)

[Claims] 1. In a virtual storage system having a real storage device, an external storage device, and a paging control means for managing page-in and page-out between the real storage device and the external storage device, the paging control means An external page allocation control method characterized in that when allocating a slot group of an external storage device to a paged out external page, selection is made from the slot group closest to the slot group accessed immediately before.