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Method for Dynamically Allocating Video Memory in Situations Where Application Context is Temporarily Lost

IP.com Disclosure Number: IPCOM000009710D
Publication Date: 2002-Sep-11
Document File: 3 page(s) / 71K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that maps and un-maps physical and virtual memory, depending on which application is running in a multi-user operating system. Benefits include the elimination of both physical and virtual memory leakage.

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Method for Dynamically Allocating Video Memory in Situations Where Application Context is Temporarily Lost

Disclosed is a method that maps and un-maps physical and virtual memory, depending on which application is running in a multi-user operating system. Benefits include the elimination of both physical and virtual memory leakage.

Background

Dynamic Video Memory Technology (DVMT) manages video memory by allocating and de-allocating part of system memory as video memory required by graphics applications. When an application requests allocation of video memory it does this by first mapping a part of system memory through the Graphics Translation Table (GTT) into the physical address space of the processor, then mapping this physical memory into the user address space. When this memory is no longer needed by the application, the process is reversed by using the OS services to un-map memory from the user address space, then removing the physical memory mapping via the GTT.

In multi-user operating systems a situation arises, where one application (“A”) loses focus and another application (“B”) gains control of the system. This is called a context switch. Application “B” may go into an exclusive mode, or may cause a display mode change.

During mode changes or context switching, the OS may delete the video surfaces created by application “A” to allow application “B” to get the maximum possible system resources. This results in a request to the video driver to delete the video memory surfaces. The video driver can delete the physical memory mappi...