DOCUMENT ID:  1205-02

SYNOPSIS:     What is Paging?

OS RELEASE:   2.4

PRODUCT:      Solaris

KEYWORDS:     paging page disk i/o virtual memory


DESCRIPTION:

What is Paging?


SOLUTION:

Paging

In general, all disk I/O centers around the Virtual Memory system's role
as a cache manager. 

"Page in" requests come as a result of the cache manager's need to fill
its cache (main memory). 

"Page out" requests come when a page is written back to disk.

*       Modified pages that have not been recently referenced
        are scheduled to be written back to disk by the 
        "page" daemon.

*       Pages are written back to disk when a process is swapped
        out.

*       Modified file pages are also written synchronously back
        to disk by the "flflush" daemon and user process (msync (3),
        sync(2), and fsync(2)).


DATE APPROVED: 09/25/95