3 level caching

3 level loader benefit :

• Faster respone ( vs Disk load)
• Less RAM require (vs RAM cache

But the limited:

• Code Complex
• More CPU resource require.

3 level caching include:

VRAM (RAM of video card) <--> RAM <--> Disk

A file may be in VRAM, RAM or Disk and depend on size and frequency using.

The target. Less RAM require, Less Disk Work,  low latency.

bandwidth.
pattern

Size x Frequency = Bandwidth

100 MB x 10 = 1000 MB.
-----
RAM Cache - 100 MB
Disk work - 100 MB. (need more than 60 cycles to loading) - Low respone - More Ram Require

1MB x 100 = 1000 MB.
-------
RAM Cache - 1 MB
Disk work - 1MB (Need 1 cycles to loading). - low latency - but Less RAM Require.

Caching Rule depend on:
Base on the respone level (Priority): 5 - 4 -3 - 2 -1.
Base on RAM Size: memory of application.
Base on File size : --> RAM require - Disk Work
Base on frequency: --> RAM require - Disk work


 So in terrain case:
I remember about google map. They have something like Level of Detail :D (Web again).
- The high level mipmap (1 or 2 level) is high frequency, low latency and big size. --> VRAM cache.
- lower mipmap is current load (or prepair to load) low latency and small size --> RAM cache.
- The other lower level geomip map is less frequency, higher latency and small size --> Disk Load.


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The Art of dynamic loader.

 undone