3DLABS Permedia3 User Manual
Page 23
The Permedia3 Create! Driver
Chapter 2 - Software Configuration
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Number of DMA Sub-Buffers lets you set the number of Direct Memory Access
(DMA) sub-buffers allocated for use by OpenGL. (DMA is a technique whereby a
device can directly access memory without having to go through the CPU). Each
DMA buffer is sub-divided into sub buffers which are used in conjunction with a
queued DMA mechanism to reduce latency in the system. The number of sub buffers
can be set, with 8 as the default. Setting it to 2 will disable the queued DMA
mechanism.
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Wait for Vblank lets you determine whether the OpenGL driver will attempt to
synchronize screen updates to the vertical blanking interval. Smooth animation of 3D
applications can be achieved by rendering (drawing) to an off-screen window/
desktop sized color buffer and copying or swapping the contents to the displayable
front buffer at the completion of each frame.
This option is enabled as the default so that there is no visible tearing. Disabling this
option gives the highest rendering frame rates of double buffered applications. You
should disable this option for instance when running benchmarks.