Kumar V Nallapati

US Patent:

6711644, Mar 23, 2004

Filed:

Jul 27, 2000

Appl. No.:

09/627226

Inventors:

Mathew Accapadi - Austin TX
Kumar V. Nallapati - Austin TX
Mysore Sathyanaraya Srinivas - Austin TX
James William VanFleet - Austin TX
Nasr-Eddine Walehiane - San Francisco CA
Michael William Wortman - Cedar Park TX

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1324

US Classification:

710263

Abstract:

An apparatus and method for communicating the completion of asynchronous I/O requests is provided. In particular, the apparatus and method make use of a new function call which is capable of waiting for a predetermined number of I/O requests to be completed prior to returning to the calling application. Control blocks for the I/O requests are updated after a predetermined number of I/O requests have been completed, i. e. in a process context rather than in an interrupt context as in the known systems. In this way, the overhead associated with known asynchronous I/O system calls is reduced.

US Patent:

62336665, May 15, 2001

Filed:

Sep 17, 1998

Appl. No.:

9/156129

Inventors:

Thomas Stanley Mathews - Austin TX
Kumar V. Nallapati - Austin TX
David William Sheffield - Austin TX

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 1200
G06F 1206

US Classification:

711203

Abstract:

A data processor controlled system for providing virtual memory comprising a data processor memory for storing a plurality of real memory pages, secondary storage unit and a memory management control unit for moving the real memory pages into and out of the secondary storage unit wherein each real memory page is respectively stored as a virtual memory page. The invention provides a system and method for deferred allocation of space for a real memory page in the secondary storage unit for recording the address of the space in a table having a plurality of table pages for recording the secondary storage addresses of each of said virtual memory pages. The system includes control unit responsive to the moving of a memory page into the secondary storage, and determining whether the initial table page for recording the address of the moved page is present in the data processor memory, the control unit further responsive to the determining unit for moving, without any external process interrupts, the initial table page into the data processor memory if the initial table page is not present, and the recording unit for recording the address of the moved page into the initial page.

US Patent:

58095616, Sep 15, 1998

Filed:

Oct 7, 1996

Appl. No.:

8/726975

Inventors:

David William Sheffield - Austin TX
Kumar Nallapati - Austin TX
Mark Douglass Rogers - Austin TX

Assignee:

International Business Machines Corp. - Armonk NY

International Classification:

G06F 1200

US Classification:

711206

Abstract:

An improved method and apparatus for managing real pages, also called physical pages, and virtual pages, also called logical pages, in a virtually indexed cache that is implemented as two physical caches. A list of free real pages that is a doubly linked list with a single anchor in addition to the free real pages is created. The pages are sequentially associated with each other using two sets of pointers. A set of forward pointers are used with the first pointer connecting the anchor page to the first physical page in the list and subsequent pointers connecting subsequent pages with each other with the last page having a pointer pointing to the anchor page. A set of backward pointers are employed with the first pointer pointing from the anchor to the last page in the list with subsequent pointers traversing the list towards the first page with the first page having the last pointer pointing to the anchor page. When a request for a real page is received to assign to a virtual page, an identification of whether the virtual page is an even or odd virtual page is made. The last real page in the list is assigned in response to a determination that the virtual page is an even virtual page.