Browse Prior Art Database

Extending Open File Limit for 386 HPFS While Conserving Memory

IP.com Disclosure Number: IPCOM000106279D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Lillie, BT: AUTHOR [+2]

Abstract

Disclosed is an extension for the 386 HPFS file system that is part of the OS/2 LAN Server 3.0 product which runs on OS/2 2.0. The 386 HPFS file system includes a Ring 0 server which communicates directly to the file system, bypassing the OS/2 kernel. The server component of the 386 HPFS file system only provides for 8192 handles which could be used for either files or searches. The file handle is used as an index for two arrays which contain additional information on each open file and search. For each file handle available, 5 bytes were needed. The two arrays were allocated out of the file systems data segment at load time, which meant that the memory was always in use, even when the server was not running. Handles used for files are 16 bits in length, and handles used for searches are limited to only 13 bits.

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Extending Open File Limit for 386 HPFS While Conserving Memory

      Disclosed is an extension for the 386 HPFS file system that is
part of the OS/2 LAN Server 3.0 product which runs on OS/2 2.0.  The
386 HPFS file system includes a Ring 0 server which communicates
directly to the file system, bypassing the OS/2 kernel.  The server
component of the 386 HPFS file system only provides for 8192 handles
which could be used for either files or searches.  The file handle is
used as an index for two arrays which contain additional information
on each open file and search.  For each file handle available, 5
bytes were needed.  The two arrays were allocated out of the file
systems data segment at load time, which meant that the memory was
always in use, even when the server was not running.  Handles used
for files are 16 bits in length, and handles used for searches are
limited to only 13 bits.

      Simply increasing the size of the arrays introduces additional
problems.  First, since the arrays are fixed at load time, the memory
overhead is significant.  Second, since the search handles are
limited to 13 bits, no more than 8192 handles can be used for
searches.

      To solve the limitations imposed by the search handle length,
two sets of arrays are used.  One set is used for the searches, and a
second set for file handles.  The memory management functions of OS/2
2.0 allow greater flexibility in allocated space for the arrays.
When the server starts, a li...