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Automatic Synchronization of Multiple Mapped Segments

IP.com Disclosure Number: IPCOM000062556D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Duvall, KE: AUTHOR [+3]

Abstract

By modifying the Copy-on-Write function, synchronization of a common access file on a triggered basis (automatic synchronization) is achieved. It would be desirable to automatically synchronize Copy-on-Write for common files in a UNIX* environment. By modifying the Copy-on- Write function in the following manner, synchronization of common access files on a triggered basis (automatic synchronization) has been achieved. A system parameter is set at initialization time to define the trigger granularity in Hertz. A flag is set in the information node (i-node) structure in the SHMAT system call, indicating that autosync is enabled. When the autosync function is enabled by any single user, the autosync function is transparent to all users. The autosync function works as follows: 1.

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Automatic Synchronization of Multiple Mapped Segments

By modifying the Copy-on-Write function, synchronization of a common access file on a triggered basis (automatic synchronization) is achieved. It would be desirable to automatically synchronize Copy-on-Write for common files in a UNIX* environment. By modifying the Copy-on- Write function in the following manner, synchronization of common access files on a triggered basis (automatic synchronization) has been achieved. A system parameter is set at initialization time to define the trigger granularity in Hertz. A flag is set in the information node (i-node) structure in the SHMAT system call, indicating that autosync is enabled. When the autosync function is enabled by any single user, the autosync function is transparent to all users. The autosync function works as follows: 1. The Read/Write segment is purged (all changed pages are written to non-volatile memory) and then unmapped. 2. The oldest private Copy-on-Write segment is purged, followed by purging of all other private Copy-on-Write

segments based upon order of creation. 3. If a shared Copy-on-Write segment exists, it is purged last. 4. All Copy-on-Write segments are unmapped; the Read/Write is then remapped followed by the remapping of all

Copy-on-Write segments. * Trademark of AT&T Bell Laboratories.

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