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    3.
    发明专利
    未知

    公开(公告)号：BR8700178A

    公开(公告)日：1987-12-01

    申请号：BR8700178

    申请日：1987-01-16

    Applicant: IBM

    Inventor： DUVALL KEITH ELLIOT ,  HOOTEN ANTHONY DANA ,  O'QUIN JOHN CLAUDE III ,  SMITH TODD ALLEN

    IPC: G06F9/46 ,  G06F12/08 ,  G06F12/14

    Abstract: A method for automatically extending the size of a segment in a page segmented virtual memory data processing system which increases the size of a segment in blocks of 64K virtual pages in response to the system detecting that the requested page has been protected. The conventional UNIX type System Calls create and open files in virtual memory. All pages are protected "read only" until a SHMAT type System Call is made to operate on a page at a specific address. At that point in the process, a protection exception is recognised by the system and the UNIX kernel takes control to remove the protection and update the appropriate data structures to reflect the new status of the page and the addresses in real memory where the page may be found. Segments containing mapped files are also extended by the method.

    4.
    发明专利
    未知

    公开(公告)号：BR8700180A

    公开(公告)日：1987-12-01

    申请号：BR8700180

    申请日：1987-01-16

    Applicant: IBM

    Inventor： O'QUIN JOHN THOMAS II ,  O'QUIN JOHN CLAUDE III ,  ROGERS MARK DOUGLASS

    IPC: G06F12/10 ,  G06F12/08

    Abstract: In a virtual memory data processing system, the use of a pageable External Page Table data structure for recording current status and disk address information for each virtual page in the system and a non-pageable or pinned table of tables, provides improved system performance when a large number of virtual pages are to be operated on in the same manner. As disclosed, each page of External Page Table entries can record a predetermined number of entries (512), depending on the byte capacity of each virtual page (2,048) and the size of each entry (4 bytes). One page of 512 entries corresponds to 1 megabyte of virtual storage (512 x 2,048) and also appears as one entry in a pinned External Page Table. The pinned External Page Table is referred to as the "XPT of the XPT," and has the same format as the pageable XPT. A 256 megabyte segment of virtual memory is representable in the XPT of the XPT by 256, 4 byte entries, or one-half of a page. … Where all virtual pages represented by a page of XPT entries are to be processed in the same way (i.e., created, destroyed), one operation on one entry in the XPT of the XPT is made, rather than 512 operations on the 512 entries of the XPT.

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