International Business Machines Corporation

Danny R Sutherland

Jeffrey Douglas Haggar

Harris M Morgenstern

Steven Jay Greenspan

Carl Edward Clark

Elpida Tzortzatos

Peter Bergersen Yocom

Paul Gregory Greenstein

John Ted Rodell

Greg A Dyck

Jeffrey Mark Nick

Robert R Rogers

Charles E Mari

Donald Fred Ault

David B Emmes

Deborah Elizabeth Neuhard

Barbara J Bryant

Roman Anthony Bobak

Tri M Hoang

Mariama Ndoye

Wendy L Wang

Tracy D Butler

Glen E Garrison

Kenneth G Rubsam

Eugene S Schulze

David C Manners

Peter B Yocum

Jim H Mulder

In a computing system having swappable and non-swappable address spaces, wherein the computing system includes an operating system that includes a Real Storage Manager (RSM), a Systems Resource Manager (SRM) and a Region Control Task (RCT), a method for recovering swappable fixed non-preferred memory is provided which includes receiving a request from the operating system to configure an area of real memory to create an intercepted swappable address space, wherein the intercepted swappable address space includes a flagged fixed frame element identified for configuration, examining the intercepted swappable address space so as to determine if the intercepted swappable address space will remain swappable, requesting the SRM to coordinate the swapping process, quiescing the intercepted address space, generating a first return code responsive to the intercepted swappable address space remaining swappable, communicating the first return code to the RCT so as to cause the RCT to respond to the first return code, instructing the RSM to proceed based on the first return code, examining the intercepted swappable address space so as to identify the flagged frame elements, exchanging the flagged frame elements with unflagged frame elements, updating dynamic address translation tables, and returning a performance code to the RCT so as to indicate recovery success or recovery failure. A method for recovering swappable fixed non-preferred memory where the originally swappable address space has been converted into non-swappable address space is also provided.

Method for recovering memory

In a computing system implementing a virtual memory system having real memory storage frames for storing virtual pages of data and an auxiliary storage system comprising auxiliary storage slots for storing copies of corresponding virtual pages provided in real storage frames, a system and method for freeing auxiliary storage slots to enable further copying of pages thereto. The method comprising the steps of: a) traversing a queue of page frame table entries indicating presence and location of virtual page data in the real storage system; b) determining from the real storage frame backing a page whether the page has been changed in the real storage, and in response, determining whether the page is backed in a corresponding slot in auxiliary storage; c) identifying the auxiliary slot corresponding to the changed frame; and, b) removing the virtual page in said corresponding slot in said auxiliary storage, wherein further room is made available in said auxiliary storage for accommodating storage of other virtual page entries.

Auxiliary storage slot scavenger

A sectioned ordered queue in an information handling system comprises a plurality of queue sections arranged in order from a first queue section to a last queue section. Each queue section contains one or more queue entries that correspond to available ranges of real storage locations and are arranged in order from a first queue entry to a last queue entry. Each queue section and each queue entry in the queue sections having a weight factor defined for it. Each queue entry has an effective weight factor formed by combining the weight factor defined for the queue section with the weight factor defined for the queue entry. A new entry is added to the last queue section to indicate a newly available corresponding storage location, and one or more queue entries are deleted from the first section of the queue to indicate that the corresponding storage locations are no longer available. Various processes associated with a real storage manager are responsible for keeping the queue sections in balance, updating the queue sections, and removing entries from the queue to &ldquo;steal&rdquo; real storage frames.

Method and apparatus for maintaining order in a queue by combining entry weights and queue weights

An exemplary embodiment of the invention is a virtual memory structure having a first virtual memory space and a virtual page frame table space. The first virtual memory space includes at least one private area and at least one common area. The virtual page frame table space is separate from the first virtual memory space. The virtual page frame table space includes at least one page frame table entry representing a frame of real memory.

Virtual memory structure

A system and method for eliminating excessive spin conditions on systems implementing a LRU algorithm. This is achieved by limiting the amount of time a LRU task is allowed to run in any one invocation. If this time limit is exceeded before the LRU task has completed its processing, the LRU task will reschedule itself to run after a short time interval, record which frames have been processed so far, release its serialization resources, and exit to open a window of enablement. During this window, other processes that were spinning for the serialization resources can have a chance to run. When the LRU task runs again it will re-obtain the serialization resources and continue processing frames that were not previously processed. The above process will be repeated until all the appropriate frames in the system are in LRU order.

Excessive spin detection and avoidance for systems using a least recently used page replacement algorithm

In a computing system implementing a virtual memory system having real memory storage frames for storing virtual pages of data and an auxiliary storage system comprising auxiliary storage slots for storing copies of corresponding virtual pages, wherein I/O mechanisms are employed for effectuating transfer of data between auxiliary and real storage, a system and method for managing storage of unvirtualized dataset pages destined for auxiliary storage in a manner so to avoid I/O operations when assigning or moving VIO dataset data. The system and method is used to allow faster access to VIO data set pages by allowing that data to be kept in real storage.

Managing unvirtualized data pages in real storage

Segments of storage of a computer system are shared among any number of users at varying virtual addresses. The virtual addresses can be in the same address space or different address spaces. The sharing of a segment of storage is provided by storing the real address of a page table corresponding to the segment of storage to be shared at different virtual addresses. This allows users of the same or different address spaces to share the same segment of storage by referencing the same page table.

Sharing segments of storage by enabling the sharing of page tables

An indicator is provided in a Page Frame Table Entry to identify a page frame as &ldquo;Permanently Non-Preferred&rdquo; (PNP). The indicator is set for page frames in storage subincrements which have locations corresponding to page frames determined to be &ldquo;bad&rdquo; (permanent errors) during system IPL, when reconfiguring storage on-line, or when a storage-related error occurs for such a frame during system execution. Mechanisms are provided to convert even PNP page frames to preferred status when shortages of preferred pages exist; but the mechanism used for choosing PNP frames, and for determining which PNP frames to convert to preferred status when conversion is needed, increase the likelihood of locating a target subincrement to use in copying pages from a preferred storage subincrement when the preferred storage is taken off-line.

Method and apparatus for storage resource reassignment utilizing an indicator to enhance the likelihood of successful reconfiguration

A multisystem log stream of a multisystem environment is compressed. The oldest record needed for each system that can write or delete entries from the multisystem log stream is tracked, and that information is used in compression of the log stream. The block ids associated with those oldest records are maintained within a vector, and when the vector is updated, a determination is made as to whether the entry in the vector that it replaced previously contained the lowest block id in the vector. If so, all the records having block ids lower than the new lowest block id in the vector are deleted.

System of compressing the tail of a sparse log stream of a multisystem

One system of a multisystem environment takes over log entries owned by another system of the environment. When a system owning entries on a primary log stream is inactive (or a sync point manager on the system is inactive), another system of the multisystem environment writes the log entries corresponding to the inactive system to other locations. The entries within the other locations are not owned by any system. Thus, the resource managers associated with those log entries are eligible for restarting on any system of the multisystem environment. However, all resource managers involved in a common set of transactions are to restart on the same system. The other resource managers can restart on another system. When one of the resource managers restarts on a system, the system takes back ownership of the entries associated with the common set of transactions.

One system of a multisystem environment taking over log entries owned by

Method of one system of a multisystem environment taking over log

Tail compression of a sparse log stream of a multisystem environment

The amount of real memory space used by descriptor tables of a computer system is reduced. On system initialization, sufficient contiguous virtual memory space for each table is allotted for descriptors in the tables to define all memory space in both central storage and expanded storage. However, only descriptors for on-line storage locations, relative to a particular partition, are placed in these tables. As the system operates, the tables are continuously updated, removing descriptors for storage locations taken off-line and adding descriptors for blocks of memory brought on-line so that the tables reflect only the storage locations then on-line in the particular partition.

Allocation of real storage for hardware descriptors within virtual

A virtual storage computer system having token controlled storage protection. The computer system includes a processor, a real storage, and a virtual storage containing a user space and a system space. A virtual storage area in the user space provides a protected view of one or more pages of memory located in the real storage. A virtual storage area in the system space provides a token-accessible view of the corresponding pages of memory. To protect the pages of memory, a user program first requests that token controlled protection be provided via the virtual address in the user space and that a corresponding user token be returned by the processor. The user program stores the user token for later use when accessing the protected pages. When the user program requests access to the protected pages, the processor matches the user token with a system token to obtain a token-accessible view in the system space of the protected pages.

Virtual storage computer system having methods and apparatus for

A data processing system includes central storage where access to data is by central storage addresses. Instructions normally include a logical or virtual address which is translated to a real central storage address using dynamic address translation (DAT) with or without an access register (AR) translation mechanism. When in AR mode, and with DAT on, addressing of instructions or data in central storage can be effected by specifying real central storage addresses and eliminate the DAT and AR translating process.

Growing community of inventors

Poughkeepsie, NY, United States of America

Danny R Sutherland