International Business Machines Corporation

Matthew David Fleming

Mark D Rogers

Thomas Stanley Mathews

David Alan Hepkin

Joefon Jann

David W Sheffield

Ramanjaneya Sarma Burugula

Jonathan Allen Wildstrom

A mechanism for operating a virtual memory is provided in an operating system. The mechanism detects the existence of a central memory loan pool, identifies a segment of memory that is loanable, and transmits an indicator that the segment is available for loaning to the memory loan pool. The operating system contributing memory can monitor its actual memory capacity and reclaim the loaned segment if the amount of memory available to the loaning operating system (OS) gets below a predetermined value.

Managing memory allocations loans

Disclosed is a computer implemented method, apparatus and computer program product for communicating virtual memory page status to a virtual memory manager. An operating system may receive a request to free a virtual memory page from a first application. The operating system determines whether the virtual memory page is free due to an operating system page replacement. Responsive to a determination that the virtual memory page is free due to the operating system page replacement, the operating system inhibits marking the virtual memory page as unused. Finally, the operating system may insert the virtual memory page on an operating system free list.

Selectively mark free frames as unused for cooperative memory over-commitment

Disclosed is a computer implemented method and apparatus for marking as critical a virtual memory page in a data processing system. An operating system indicates to a virtual memory manager a virtual memory page selected for paging-out to disk. The operating system determines that the data processing system is using a cooperative memory over-commitment. The operating system, responsive to a determination that the data processing system is using cooperative memory over-commitment, marks the virtual memory page as critical, such that the virtual memory page remains in physical memory. The operating system, responsive to marking the virtual memory page as critical, sets the virtual memory page to a page-out state.

Mark page-out pages as critical for cooperative memory over-commitment

A system and method of allocating contiguous real memory in a data processing system. A memory controller within system memory receives a request from a data processing system component for a contiguous block of memory during operation of the data processing system. In response to receiving the request, the memory controller selects a candidate contiguous block of memory. Then, after temporarily restricting access to the candidate contiguous block of memory, the memory controller identifies a set of frames currently in use within the candidate contiguous block of memory, relocates the set of frames, and allocates the candidate block of memory for exclusive use by the requesting data processing component. The allocation of contiguous real memory occurs dynamically during the operation of the data processing system.

System and method of allocating contiguous memory in a data processing system

Methods, apparatus and computer program products for removal of elements from a linked list while other elements of the linked list are allowed to be accessed during the removal operation. In one embodiment, the method, apparatus and computer program product include identifying an add/remove area of a linked list and a static area of the linked list. Elements may only be added or removed from the linked list in the add/remove area or by a garbage collector that performs garbage collection only on elements in the static area of the linked list. The garbage collector identifies an element after the last element in the add/remove area and performs garbage collection beginning with that element and moving through the static area. In an alternative embodiment, a 'next element' pointer in a previous list element is set to point to the element being deleted's 'next element' pointer. Any global references to the element being deleted must be modified. A message may then be issued to the processors of a multiprocessor system at a same interrupt priority as a reading process priority. Once the processors respond to the message, garbage collection may be performed on the element to be deleted.

Apparatus and method for removing elements from a linked list

A method, apparatus, and computer instructions for broadcasting information. A change in data used by a number of processors in the data processing system is identified. A message is sent to the number of processors in the data processing system in which the message is sent with a priority level equal to a set of routines that use the data in response to identifying the change. This message is responded to only when the recipient is at an interrupt priority less favored than the priority of the message. A flag is set for each of the number of processors to form a plurality of set flags for the message in which the plurality of set flags are located in memory locations used by the number of processors in which the plurality of set flags remains set until a response is made to the message.

Method and apparatus for broadcasting messages with set priority to guarantee knowledge of a state within a data processing system

A method and apparatus for managing a dynamic alias page table are provided. With the apparatus and method, alias page table entries are added to an alias page table dynamically by determining if the alias page table has space for the entry and, if so, the entry describing the virtual address to physical address mapping is added to the alias page table and a successful completion is returned to the virtual memory manager. If the alias page table does not have space for the entry, a new page is used to map the next virtual page of the alias page table. This page must be marked as a fixed page if it not so marked already. This page is pinned in the software page frame table, and the hardware page table entry for this page is also pinned.

Method and apparatus for managing a dynamic alias page table

A method, apparatus, and computer instructions for managing frames. Frames intended for isolation are identified in which the frames include in-use frames and free frames. Reservation of free frames from the frames identified as intended for isolation is requested. Successfully reserved frames are moved to an isolation list. In-use frames are marked, and unisolated/unmarked frames are identified. Any free frames in the unisolated frames are moved to the isolation list. In-use frames in the unisolated frames are marked and reservation of the in-use frames in the unisolated frames is released.

Growing community of inventors

Austin, TX, United States of America

Matthew David Fleming